Thủy Nguyễn

Alexandre Thibault

Jacques Maria

PhD Chayma Ladhari

Pascale Palassin

PhD Xavier Quantin

PhD Candice Lesage

MD Guillaume Taïeb

MD Xavier Ayrignac

MD PhD Patricia Rullier

Dominique Hillaire

# Pharmd

Pascale Pharmd

Palassin

MD Dominique Hillaire-Buys

PhD Olivier Lambotte

PhD Philippe Guilpain
email: p-guilpain@chu-montpellier.fr

PhD Jean- Luc Faillie

Prof Philippe Guilpain

Rheumatic disorders associated with immune checkpoint inhibitors: what about myositis? An analysis of the WHO's adverse drug reactions database

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Almost all ICI-related-myositis (95,3%) were considered serious (i.e. requiring at least a hospitalization), with a fatality rate of 22.3%. Myocarditis and myasthenia were associated with ICI-related-myositis in 11.3% and 11.9% of cases and resulted in death in 51.3% and 26.8%, respectively.

Second, using case/non-case analyses [START_REF] Faillie | Case-non-case studies: Principle, methods, bias and interpretation[END_REF] , we found that myositis was more than seventeen times more reported with ICI agents than with any other drugs (Reporting Odds Ratio (ROR) 17.3; 95% CI: 15.5-19.2). Moreover, myositis was more reported in the group of anti-PD-1/PD-L1 monotherapy compared to anti-CTLA-4 monotherapy (OR=2.4, 95% CI 1.6-3.5). Myositis was also more frequently reported in patients using ICI combination therapy versus those using ICI monotherapy (OR=1.8, 95% CI 1.3-2.4). Similar results were obtained after adjusting for potential confounders such as sex, age and reporter type.

Herein, we report a considerable outbreak of ICI-related myositis in the past years.

Vigibase represents the largest medical post-marketing surveillance database allowing the study of ADRs in real conditions of use and facilitates the study of rare ADRs such as myositis, which is hardly observed in clinical trials or observational studies with limited sample size. A previous work by Anquetil et al. identified 180 ICI-related-myositis reported through March 2018 [START_REF] Anquetil | Immune Checkpoint Inhibitor-Associated Myositis[END_REF] .

With 165 additional cases, we report the largest series of ICI-related-myositis and further characterize this unique ICI-related-ADR using disproportionality (case/non-case) analyses, a method designed for early detection of pharmacovigilance signals 41 . Although disproportionality estimates cannot be interpreted as risk estimates, they have been shown to be significantly correlated to risk estimates [START_REF] Maciá-Martínez | An Empirical Approach to Explore the Relationship Between Measures of Disproportionate Reporting and Relative Risks from Analytical Studies[END_REF] .

Interestingly, ICI-related-myositis seems to differ greatly in comparison to primitive inflammatory muscle disorders (IMD), suggesting a novel and unique emerging autoimmune entity with specific concerns. Indeed, clinical manifestations in ICI-related-myositis include frequent bulbar symptoms, ptosis and oculomotor impairment, whereas those are rare in primitive myositis, but may occur in myasthenia gravis, a disorder affecting neuromuscular junction. Hence, the association between immune-related myositis and myasthenia gravis may not be fortuitous as shown here and by others even if specific antibodies against acetylcholine receptor may be lacking 8-10, . Interestingly, the great majority of myasthenia gravis cases was not observed with anti-CTLA-4 agents, but rather with anti-PD-1/PD-L1 agents, suggesting an increased risk with the latter, in line with our proper observations [START_REF] Ramos-Casals | Sicca/Sjögren's syndrome triggered by PD-1/PD-L1 checkpoint inhibitors. Data from the International ImmunoCancer Registry (ICIR)[END_REF] .

Of note, the majority of the reports were merely qualified as "myositis", even if some also referred to specific entities. This may originate from reporting difficulties but questions the complex nosology in IMD. Actually, the classification of IMD improved considerably in the last years and now distinguishes definite entities according to clinical presentation, specific auto-antibody profiles, histological patterns, associated with distinct prognoses. If these data may be lacking in Vigibase, case reports have characterized ICI-myositis as driven by T-CD8lymphocyte and macrophages infiltrates together with fiber necrosis, a description close to necrotizing myositis [START_REF] Salem | Cardiovascular toxicities associated with immune checkpoint inhibitors: an observational, retrospective, pharmacovigilance study[END_REF] . Reports have described circulating antibodies against anti-synthetase, PM-SCL, SRP and TIF-1-gamma [START_REF] Moreira | Myositis and neuromuscular side-effects induced by immune checkpoint inhibitors[END_REF]14 . Noteworthily, the latter is strongly associated with cancer and considered as a paraneoplastic syndrome (PNS) in this context. By analogy with other preexisting autoimmune conditions, the use of ICIs in the context of PNS may be associated with an increased risk for immune toxicity, including PNS flare 14 . Beyond these considerations, the association with other autoimmune entities may also be of interest, since myositis can also stand as a manifestation of other connective tissue disorders, such as lupus, scleroderma or Sjögren syndrome [START_REF] Ramos-Casals | Sicca/Sjögren's syndrome triggered by PD-1/PD-L1 checkpoint inhibitors. Data from the International ImmunoCancer Registry (ICIR)[END_REF] .

Importantly, another major concern with ICI-related-myositis is the strong association with myocarditis. In accordance with our results, other series 6 12 revealed high prevalence of myocarditis (ranging from 15 to 32%) in patients with ICI-related-myositis, together with high lethality (up to 50%). In another study on VigiBase, which focused on ICI-related myocarditis, musculoskeletal disorders were the most frequent concurrent complications occurring along with myocarditis [START_REF] Salem | Cardiovascular toxicities associated with immune checkpoint inhibitors: an observational, retrospective, pharmacovigilance study[END_REF] . Thus, the increased prevalence of myocarditis may explain the higher mortality rate in ICI-related-myositis compared with primitive IMD, and prompts for a systematic cardiac screening in these patients.

In conclusion, despite the limitations inherent to pharmacovigilance studies which are concerned with under-reporting, we confirm a strong signal suggesting an increasing risk of myositis associated with ICIs, especially anti-PD-1/PD-L1 agents or when these drugs were used in combination with anti-CTLA-4 agents. Prospective studies will be necessary to better investigate this risk, and better define the place of ICI-related-myositis within the spectrum of IMD. In the meantime, clinicians' awareness and vigilance are needed to improve early detection and management of this unique and severe complication. In this context, the specific risk of myocarditis, a life-threatening complication, prompts to a systematic screening.

ACKNOWLEDGMENTS, FUNDING SOURCE AND COMPETING INTERESTS

The Uppsala Monitoring Centre has provided the data, but the study results and conclusions are those of the authors and not necessarily those of the Uppsala Monitoring Centre, National Centers, or WHO.

Table . Characteristics of ICI-exposed myositis cases Characteristics ICI-exposed myositis cases (n= 345)

 .

	Age (years), median (P25-P75) (n=265)	71 (63-76)
	Sex, n (%)
	Male	228 (69.7)
	Female	99 (30.3)
	Unknown	18
	Reporter type, n (%)
	Health professional	293 (86.2)
	Other	47 (13.8)
	Unknown	5
	Reporting year, n (%)
	2019	4 (1.2)
	2018	184 (53.3)
	2017	90 (26.1)
	2016	47 (13.6)
	2008-2015	20 (5.8)
	Cancer type, n (%)
	Lung cancer	111 (34.8)
	Skin cancer	109 (34.2)
	Melanoma	102 (32.0)
	Other cancers	32 (31%)
	Exposure to ICIs
	Monotherapy, n (%)	294 (85.2)
	Anti-PD-1	252 (73.0)
	Nivolumab	154 (44.6)
	Pembrolizumab	97 (28.1)
	Nivolumab or pembrolizumab	1 (0.3)
	Anti-PD-L1	15 (4.3)
	Atezolizumab	7 (2.0)
	Avelumab	3 (0.9)
	Durvalumab	5 (1.4)
	Anti-CTLA-4	27 (7.8)
	Ipilimumab	27 (7.8)
	Tremelimumab	0 (0.0)
	Combination therapy	51 (14.8)
	Nivolumab/ipilimumab	49 (14.2)
	Pembrolizumab/ipilimumab	1 (0.3)
	Durvalumab/tremelimumab	1 (0.3)
	Time to onset (days) (n=97)
	Median (P25-P75)	33 (19 -57)
	Min-Max	1-606
	Reported myositis term
	Myositis	276 (80.0)
	Dermatomyositis	25 (7.2)
	Polymyositis	20 (5.8)
	Immune-mediated necrotizing myopathy	13 (3.8)
	Orbital myositis	8 (2.3)
	Inclusion body myositis	2 (0.6)
	Anti-synthetase syndrome	1 (0.3)
	Specific co-reported irAEs
	Myocarditis	39 (11.3%)
	Myasthenia	41 (11.9%)
	Death, n (%)	77 (22.3)

This study did not receive any specific funding.

ATJM has received fees from Abbvie, Actelion, CSL Behring, Experf, Novartis and Shire and declares speaking fees from Astra-Zeneca and BMS in the last 5 years.

PG is a medical expert for LFB (Laboratoire Français du Biofractionnement) and has received fees from Abbvie, Actelion, Boehringer Ingelheim France, Bouchara-Recordati, Novartis, Pfizer, and Roche in the last 5 years.

OL has received expert testimony and consultancy fees from BMS France, MSD, Astra Zeneca; consultancy fees from Genzyme, Incyte, and expert testimony for Janssen.

Other authors declare that they have no conflicts of interest.


Dr Spyridon N Karras
email: karraspiros@yahoo.gr

Stergios Α Polyzos

Danforth A Newton

Carol L Wagner

Bruce W Hollis

Jody Van Den Ouweland

Erdinc Dursun

Duygu Gezen-Ak

Kalliopi Kotsa

Cédric Annweiler

Cedric Annweiler

Declan P Naughton

Adiponectin and vitamin D-binding protein are independently associated at birth in both mothers and neonates

Keywords: adipokines, adiponectin, irisin, neonates, vitamin D, vitamin Primary care . Main Outcomes Features: Biochemical markers from maternal and cord: VDBP, adiponectin, irisin, calcium, albumin, parathyroid hormone, 25OHD,

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

gestation, maternal age, BMI. The finding of a strong association of VDBP (355.3 ± 29.2 μg/ml) and adiponectin (11.9 ± 2.0 μg/ml) but not irisin (174.4 ± 26.0 ng/ml), was also evident in neonates (p=0.03 and p=0.94, respectively). No association was observed in both maternal and neonatal vitamin D, adiponectin and irisin.

Conclusions:

The main findings of this study are i) the perspective of a potential independent interaction of VDBP and adiponectin in both mothers and neonates and ii) the lack of a causative model effect of both maternal/neonatal vitamin D status and adipokine profile on neonatal anthropometry at birth, as a surrogate marker of future metabolic health of the offspring.

Precis

In mother-neonate pairs at birth, adiponectin is independently associated vitamin D binding protein but not vitamin D status or significant anthropometric indices.

Introduction

Vitamin D, recognised as essential for maintaining bone homeostasis and calcium absorption [START_REF] Dusso | Vitamin D[END_REF][START_REF] Holick | Vitamin D deficiency[END_REF], has been recently established as a biological contributor in different cells and tissues [START_REF] Rajakumar | Solar ultraviolet radiation and Vitamin D: a historical perspective[END_REF][START_REF] Block | Nutrient sources in the American diet: quantitative data from the NHANES II survey. I. Vitamins and minerals[END_REF][START_REF] Prosser | Enzymes involved in the activation and inactivation of vitamin D[END_REF]. Despite having endogenous and dietary sources, hypovitaminosis D insufficiency and deficiency is common in all ages [START_REF] Karras | Maternal vitamin D levels during pregnancy and neonatal health: evidence to date and clinical implications[END_REF][START_REF] Ritterhouse | Vitamin d deficiency in a multiethnic healthy control cohort and altered immune response in vitamin D deficient European-American healthy controls[END_REF][START_REF] Palacios | Is vitamin D deficiency a major global public health problem?[END_REF].

Numerous studies have investigated the association between vitamin D and disease onset or remission in a range of conditions including obesity, inflammation and insulin resistance [START_REF] Jackson | Associations of 25-hydroxyvitamin D with markers of inflammation, insulin resistance and obesity in black and white communitydwelling adults[END_REF][START_REF] Dhaliwal | The vitamin D dose response in obesity[END_REF][START_REF] Mangin | Inflammation and vitamin D: the infection connection[END_REF][START_REF] Grammatiki | Vitamin D and diabetes mellitus: Causal or casual association?[END_REF]. Recent advances in analytical capability have led to increasing interest in the roles of a wider range of molecules in the vitamin D metabolome [START_REF] Shah | Exploring the role of vitamin D in type 1 diabetes, rheumatoid arthritis, and Alzheimer disease: new insights from accurate analysis of 10 forms[END_REF][START_REF] Black | Analytical bias in the measurement of serum 25hydroxyvitamin D concentrations impairs assessment of vitamin D status in clinical and research settings[END_REF]. These advances, including accurate measurements of vitamin D forms, extend to the role of vitamin D-binding protein (VDBP), which primarily contributes to the transportation in the bloodstream of vitamin D metabolites [START_REF] Dusso | Vitamin D[END_REF].

VDBP binds up to 80% of circulating vitamin D, playing a key role in regulating bioavailability and bioactivity of vitamin D, increasing its plasma half-life and modulating its distribution to target tissues. Therefore, its measurement along with vitamin D concentrations seems to be of importance [START_REF] Chun | Vitamin D and DBP: the free hormone hypothesis revisited[END_REF]. Moreover, VDBP has been hypothesized to exert regulatory immunological and metabolic actions [START_REF] Delanghe | Behind the scenes of vitamin D binding protein: more than vitamin D binding[END_REF].

Prior studies have investigated the relationship between vitamin D and adipokines.

Adiponectin, secreted from adipose tissues, has key functions in energy homeostasis, including insulin action, food intake and metabolism [START_REF] Kadowaki | Adiponectin and adiponectin receptors[END_REF]. A proteomic study identified downregulation of adiponectin in vitamin D deficient obese children, and importantly a 12-month vitamin D 3 supplementation course increased adiponectin levels [START_REF] Kadowaki | Adiponectin and adiponectin receptors[END_REF]. In isolated adipocytes, 1,25-(OH) 2 D 3 increased adiponectin [START_REF] Kadowaki | Adiponectin and adiponectin receptors[END_REF]. On the other hand, vitamin D supplementation did not increase adiponectin levels in a recent meta-analysis of 9 randomized controlled trials (RCTs) (18). Taken together, the interaction between vitamin D and adiponectin may be condition-specific and affected by a number of mechanisms, including adipogenic gene expression and adipocyte apoptosis [START_REF] Abbas | Physiological functions of Vitamin D in adipose tissue[END_REF].

Irisin, a myokine secreted primarily by skeletal muscle, is inversely correlated with vitamin D levels in small gestational age newborns [START_REF] Keleş | Evaluation of cord blood irisin levels in term newborns with small gestational age and appropriate gestational age[END_REF]. Previous reports linked irisin with circulating vitamin D levels [START_REF] Al-Daghri | Impact of vitamin D correction on circulating irisin: a 12 month interventional study[END_REF]. To date, there have been no reports of associations between adiponectin or irisin and VDBP.

VDBP concentrations are known to increase in pregnancy. In addition, body weight and adipokine profile at birth, have been recently associated with fat mass in late childhood and adolescence, respectively [START_REF] Simpson | Programming of adiposity in childhood and adolescence: associations with birth weight and cord blood adipokines[END_REF]. The potential role of VDBP as a mediator, confounder or neither in the metabolic regulation of maternal and offspring adipokine profile has not been investigated so far.

The primary aim of this study was to explore the association between adiponectin, irisin and VDBP concentrations in both mothers and neonates at birth of full-term and uncomplicated pregnancies. Secondary aims were to investigate the associations between neonatal anthropometric parameters, and maternal and neonatal adiponectin, irisin, VDBP, 25OHD and 1,25(OH) 2 D. The results of this study may provide insight in the physiological associations of VDBP beyond vitamin D, and possibly provide the basis for further research.

Patients and methods

Study population

This was a cross-sectional study of pregnant women and their neonates, conducted from April 2014 until October 2015. Recruitment was discontinued from November 2014 to March 2015 to minimize significant seasonal variation of study findings with regard to maternal and neonatal vitamin D status. Pregnant women were recruited from the Maternity Unit of the First Department of Obstetrics and Gynaecology, Aristotle University, Thessaloniki, Greece, with latitude of 40°N. All women were fair skinned. Inclusion criteria were age>18 years, body mass index (BMI)≤30 kg/m 2 and full-term pregnancy (37-42 th gestational week). Maternal non-inclusion criteria were BMI ≥30 kg/m 2 , primary hyperparathyroidism, secondary osteoporosis, osteomalacia, liver disease, hyperthyroidism, nephrotic syndrome, inflammatory bowel disease, rheumatoid arthritis, morbid obesity, gestational or pre-existing diabetes, active infection and use of medications affecting calcium or vitamin D homeostasis. Neonatal non-clusion criteria were prematurity ≤37 weeks of gestation, being small and large-for-gestational age neonates and the presence of severe congenital anomalies, as a result of one or more genetic, infectious, nutritional or environmental factors including heart and neural tube defects and Down syndrome.

The study protocol conformed to the ethical guidelines of the 1975 Declaration of Helsinki and was approved by the ethics committee of Medical School of Aristotle University of Thessaloniki. All mothers provided written informed consent for themselves and for their neonates.

Methods

Demographic and anthropometric data

At enrolment, demographic and social characteristics were recorded. Maternal prepregnancy BMI was either normal (18-25 kg/m 2 ) or overweight (25-30 kg/m 2 ). We collected maternal, infant, and labor data from the medical records, collected umbilical cord blood samples at the time of delivery, and stored aliquots of plasma and serum at -70 o C until assays were performed. We also evaluated neonatal anthropometry at birth. All neonatal anthropometric measurements were performed by the same trained nurse, between 12h and 72h of age according to standard techniques [START_REF] Mcgrath | Seasonal fluctuations in birth weight and neonatal limb length; does prenatal vitamin D influence neonatal size and shape?[END_REF][START_REF] Keeping | Determinants and components of size at birth[END_REF]. The following measurements were recorded: birth weight, height, neck-rump, upper arm, femur and knee heel lengths; head, chest, abdominal, upper arm and middle thigh circumferences, and abdominal skinfold thickness.

The birth weight of the neonates was measured on regularly calibrated scales. Knee-heel length was measured with a hand-held BK5 infant knemometer (Force Technology, Brondby, Denmark). Instrument software calculated the mean of 10 sequential readings and generated a printed report of all readings and the calculated mean. We also measured neonatal height to the nearest millimeter using an Ellard newborn lengthboard (Ellard Instrumentation Ltd., Seattle, WA). Abdominal, upper arm and middle thigh head, mid-upper arm, and maximal head circumferences were measured using a plastic encircling tape (Child GrowthFoundation, London, UK).

Abdominal, skin fold was measured using Holtain calipers (Holtain, Crymych, UK).

Biochemical and hormonal assays

Blood samples were obtained from mothers by antecubital venipuncture 30-60 minutes before delivery. Umbilical cord blood was collected immediately after clamping, from the umbilical vein. Calcium (mg/dl), albumin, parathyroid hormone (PTH) (pg/mL, 25OHD (ng/ml) 1,25(OH) 2 D (pg/ml), VDBP (μg/ml) adiponectin (μg/ml) and irisin (ng/ml) were measured in one batch at the end of the study.

Corrected calcium was calculated based on total calcium and albumin concentrations using standard equation [Corrected calcium= 0.8 ×(4 -serum albumin)]. Biochemical analysis of total calcium and albumin were performed with standard methods using the Cobas INTEGRA clinical chemistry system (D-68298; Roche Diagnostics, Mannheim, Germany). PTH was measured with electro-chemiluminescence immunoassay (ECLIA; Roche Diagnostics GmbA, Mannheim, Germany). The reference range for PTH was 15 -65 pg/ml, functional sensitivity 6.0 pg/ml, withinrun precision 0.6 -2.8% and total precision 1.6 -3.4%. VDBP, irisin and adiponectin were measured with enzyme-linked immunosorbent assay (ELISA) on a Synergy H1 Hybrid reader and Gen5 software (BioTek, Winooski, VT, USA): Gc-Globulin/VDBP (AssayPro, St. Charles, MO, USA); irisin (MyBioSource, San Diego, CA, USA); adiponectin (R&D Systems, Minneapolis, MN, USA). 25OHD and 1,25(OH) 2 D were measured by radioimmunoassay using commercial kits obtained from DiaSorin Corporation (Stillwater MN, USA). Intra-assay and inter-assay variance was 5% and 11% for 25(OH)D and 8% ,< 12% for 1,25(OH) 2 D, respectively). Intra-assay and inter-assay variance was <8% and <10% for adiponectin and <8% and <10%

for irisin ,respectively. Detection limits for assays were 0.098 μg/ml for VDBP, 3.12 ng/ml for irisin,0.039 μg/ml for adiponectin, 5 ng/ml -100 ng/ml for 25OHD and 7.5-100 pg/ml for 1,25(OH) 2 D.

Vitamin D status (25OHD) was classified as sufficient or insufficient according to consensual Institute of Medicine criteria [sufficiency: 20-40 ng/ml (50-100 nmol/L); insufficiency < 20 ng/ml (50 nmol/L) (25).

3. Statistical Analysis

Continuous data are presented as mean ± standard error of the mean (SEM).

Categorical data are presented as absolute numbers and/or frequencies. Kolmogorov-Smirnov test was used to check the normality of distributions of continuous variables.

Chi-square test was used for between group comparisons, in case of categorical variables. Independent samples t-test or Mann-Whitney test was used for between group comparisons, in case of continuous variables. Spearman's coefficient (r s ) was used for binary correlations. Multiple linear logistic regression analysis (method "enter") was used to identify independent associates for adiponectin, irisin levels or other parameters when needed. For the need of regression analysis, any of the included variables that did not follow normal distribution was logarithmically transformed. Statistical analysis was performed with SPSS 21 for Macintosh (IBM Corp., Armonk, NY). Significance was set at p<0.05 in all the tests.

Results

Description of the cohort and comparative data

Seventy pairs of newly delivered neonates and their mothers were included in this study. The demographic and anthropometric characteristics of the cohort are presented in Table 1. As selected, all women were non-obese (pre-pregnancy) and apparently healthy. Their educational level was elementary in 52 (74.3%) and secondary in 14 (20%), and unknown in 4 (5.7%) women. Eleven (15.7) women had previously given birth to one child; eight (11.4%) to two; one (1.4%) to three; and one

(1.4%) to four children.

Thirty-seven (52.9%) women had received calcium supplementation during pregnancy, either 500 mg (n=30) or 1000 mg (n=7 was used as a cut-off, no statistically significant difference was observed in maternal and neonatal serum parameters between groups.

Correlations of maternal parameters

A correlation matrix for maternal parameters only is presented in Table 3. As expected, corrected calcium was inversely correlated with PTH levels, and positively with 25OHD and 1,25(OH) 2 D; 25OHD levels also were positively correlated with 1,25(OH) 2 D and height. PTH, 25OHD and 1,25(OH) 2 D levels were not correlated with VDBP, adiponectin or irisin levels. Notably, VDBP levels were positively correlated with adiponectin and irisin levels, whereas inversely with age. Adiponectin levels were inversely correlated with weight and BMI at term, and irisin levels positively with weight (Table 3).

After sequential adjustment for weeks of gestation (model 1), weeks of gestation and maternal age (model 2), weeks of gestation, maternal age and BMI (term) (model 3), maternal adiponectin and irisin levels remained significantly positively associated with VDBP levels (Table 4 and 5, respectively). However, weeks of gestation did not remain significantly associated with irisin levels (Table 5).

Correlations of neonatal parameters

A correlation matrix for neonatal parameters only is presented in Table 6.

Corrected calcium was inversely correlated with PTH levels, but not with 25OHD and 1,25(OH) 2 D levels. 25OHD levels were positively correlated with 1,25(OH) 2 D levels and upper arm length. VDBP levels were positively correlated with adiponectin, but not irisin levels. Irisin levels were inversely correlated with PTH levels and knee-heel length.

After sequential adjustment for weeks of gestation (model 1), weeks of gestation and neonate gender (model 2), weeks of gestation, neonatal gender and weight (model 3), neonatal adiponectin levels remained significantly positively associated with VDBP levels (Table 7). Νeonatal irisin remained non-significantly associated with VDBP levels, after similar sequential adjustment.

Correlations between maternal and neonatal parameters

A correlation matrix between maternal and neonatal parameters is presented in

Discussion

This is the first study to investigate potential associations between vitamin D metabolites, VDBP and adiponectin (adipokine) and irisin (myokine) in motherneonate pairs and the associations between neonatal anthropometry and maternalneonatal vitamin D, adiponectin and irisin at birth. To the best of our knowledge, we provide here the first evidence of an association between VDBP and adiponectin levels in both mothers and neonates. On the other hand, no association was observed in both maternal and neonatal vitamin D metabolites, adiponectin and irisin.

Maternal VDBP levels demonstrated a positive association with maternal adiponectin and irisin concentrations, which remained significant after adjustment for multiple potential confounders. VDBP and adiponectin, but not irisin, also were independently associated in neonates. This finding raises consideration regarding the role of VDBP as a carrier protein or regulator of biological activity of adiponectin and irisin during pregnancy. The expected rise of VDBP in the pregnant state might also distort the association, but this finding was observed in neonates as well, at least for adiponectin. Mechanistic studies are required to elucidate whether VDBP plays a carrier or regulatory role for adiponectin and/or irisin during pregnancy.

This study also confirmed data from previous observational studies [START_REF] Zhang | Maternal and cord blood adiponectin levels in relation to post-natal body size in infants in the first year of life: a prospective study[END_REF][START_REF] Kotani | Plasma adiponectin levels in newborns are higher than those in adults and positively correlated with birth weight[END_REF] showing that cord blood adiponectin levels were higher than those observed in adults.

This finding could be explained by the observed increase in adiposity with aging. The increase in adiposity is most evident in visceral adipose tissue, while there may be decreases in subcutaneous adipose tissue. being most evident in visceral adipose tissue, while there may be decreases in subcutaneous adipose tissue. This ageassociated change in body composition, where adiposity increases throughout midlife

but decreases once late-life is reached, has been consistently found in several different ethnic groups and may be influenced by dietary intake however, unlike many adipocyte derived factors, circulating adiponectin levels decrease with increasing adiposity [START_REF] Zhang | Maternal and cord blood adiponectin levels in relation to post-natal body size in infants in the first year of life: a prospective study[END_REF][START_REF] Kotani | Plasma adiponectin levels in newborns are higher than those in adults and positively correlated with birth weight[END_REF].On the other hand, irisin concentrations were lower in neonates than mothers, a finding which has been previously observed in pathological conditions, including diabetes and obesity, as well as in uncomplicated pregnancy [START_REF] Hernandez-Trejo | Relationship between irisin concentration and serum cytokines in mother and newborn[END_REF].

Differences in neonate and adult muscle mass could explain the increased concentrations of maternal irisin compared to neonatal ones ,in this study.

As previously reported ( 29), there was no correlation between maternal circulating VDBP and PTH, 25OHD and 1,25(OH) 2 D concentrations. A high estrogen status such as pregnancy ( 29) is associated with high serum VDBP concentrations.

Of note, a negative correlation of VDBP with age, was evident. Previous findings demonstrated, that serum VDBP concentrations are lower in post-than premenopausal women which could potentially be attributed to differences in estrogen status [START_REF] Pop | Vitamin D -binding protein in healthy pre-and postmenopausal women:relationship with estradiol concentrations[END_REF]. However, the finding of age related of VDBP according to age within the same pregnant cohort warrants further investigation.

Vitamin D metabolites were also not correlated with adiponectin and irisin in both mothers and neonates, although previous results, reported an association of adiponectin, advanced oxidation protein products and advanced glycation endproducts, with vitamin D status [START_REF] Krivošíková | Vitamin D levels decline with rising number of cardiometabolic risk factors in healthy adults: Association with adipokines, inflammation, oxidative stress and advanced glycation markers[END_REF][START_REF] Vaidya | The independent association between 25hydroxyvitamin D and adiponectin and its relation with BMI in two large cohorts: the NHS and the HPFS[END_REF]. However, as aforementioned, a recent metaanalysis did not indicate any significant effect of vitamin D supplementation on adiponectin profile in the general non-pregnant population (18). Although further studies are necessary, this finding may imply that vitamin D metabolites are not correlated with adiponectin irrespective of vitamin D status.

Regarding correlations between maternal and neonatal parameters, contrary to our findings, Luo et al. observed a positive correlation in adiponectin levels of maternal and fetal circulation [START_REF] Luo | Maternal and fetal leptin, adiponectin levels and associations with fetal insulin sensitivity[END_REF]. In our study however, no such association was observed for adiponectin and irisin across maternal-neonatal pairs, which possibly implies that neonatal adiponectin and irisin at birth are not substantially affected by maternal ones. The study of Luo et al. [START_REF] Luo | Maternal and fetal leptin, adiponectin levels and associations with fetal insulin sensitivity[END_REF], investigated adiponectin concentrations in maternal (at 24-28 and 32-35 weeks of gestation) and fetal circulations, whereas our study assessed these adiponectin levels at birth. This difference in the time point of maternal-neonatal sampling might be the reason for the differences between the two studies. Similar to our findings, other authors observed no correlation between maternal and umbilical cord adiponectin concentrations [START_REF] Sivan | Adiponectin in human cord blood: relation to fetal birth weight and gender[END_REF], suggesting that adiponectin in cord blood is possibly of fetal origin. With regard to potential gender differences for adipokines in neonates, no significant differences in adiponectin levels were found between female and male neonates in a previous study [START_REF] Sivan | Adiponectin in human cord blood: relation to fetal birth weight and gender[END_REF].

Upper arm length was the only anthropometric parameter associated with both maternal and neonatal 25OHD, although this association attenuated for neonates after adjustment for potential confounders. Although lower mean neonatal knee-heel length at birth has been associated with lower maternal 25OHD levels at 28-32 weeks' gestation [START_REF] Morley | Maternal 25 hydroxyvitamin D and parathyroid hormone concentrations and offspring birth size[END_REF], we were not able to confirm this association at birth. No consistent correlations were evident between maternal and neonatal adiponectin or irisin and neonatal anthropometry as well.

Although the present study was not designed for this purpose, it reported maternal and neonatal hypovitaminosis D in a sunny European area, with none receiving vitamin D supplementation according to current guidelines [START_REF] Wagner | Vitamin D administration during pregnancy as prevention for pregnancy, neonatal and postnatal complications[END_REF]. These results are consistent with previous larger scale findings from the same region [START_REF] Karras | Maternal vitamin D status during pregnancy: the Mediterranean reality[END_REF][START_REF] Karras | Hypovitaminosis D in pregnancy in the Mediterranean region: a systematic review[END_REF]. Of note, a similar pattern of distribution of hypovitaminosis D between maternal and neonatal 25OHD concentrations was observed in both mothers and neonates being at insufficiency range [START_REF] Kovacs | The role of vitamin D in pregnancy and lactation:insights from animal models and clinical studies[END_REF][START_REF] Karras | An observational study reveals that neonatal vitamin D is primarily determined by maternal contributions: implications of a new assay on the roles of vitamin D forms[END_REF][START_REF] Grant | Vitamin D during pregnancy and infancy and infant serum 25-hydroxyvitamin D concentration[END_REF].The lack of maternal vitamin D status with BMI could be attributed to the small study sample .In addition, previous findings on the association of maternal vitamin D levels and educational status (43), were also observed in this study.

The main strength of our study relies on its originality. The absence of prior reports on associations between VDBP and adiponectin warrants further mechanistic research on the role of VDBP in bioavailability and bioactivity of adiponectin. This study, however, has certain limitations. First, while the sample size was relatively small, it was sufficiently powered to show significant differences regarding the main aim of the study. Second, the cross-sectional design of the study cannot prove a causal relationship. Third, all women were Caucasian, so our results cannot be safely generalized to other ethnicities, known to differ at least in adiponectin levels.

Furthermore, multiple comparisons render some correlations prone to a false positive error. However, the association between VDBP and adiponectin and irisin remained robust after adjustment for potential confounders. Finally calcium intake was based on self-reporting and we did not systematically assess calcium intake with a validated questionnaire.

In conclusion, our study reports that neonatal anthropometry at birth was not associated with maternal or neonatal vitamin D concentrations, but suggests an independent association between VDBP and adiponectin in both mothers and neonates, and between VDBP and irisin only in mothers. These findings warrant further research on the potential role of VDBP in regulating adiponectin and irisin. Weeks of gestation was rated as 0 for <38, and 1 for ≥38, respectively.

Abbreviations: VDBP, Vitamin D-binding protein.

  Our results are in accordance with recent findings by McManus et al. (33), who reported no correlations between maternal and neonatal 25OHD and adipokine concentrations at birth in both controls and women with gestational diabetes. Unlike the present population, McManus et al. population was vitamin D sufficient (33).

Figure 1 .

 1 Figure 1. Scatter plot between adiponectin and vitamin D-binding protein in mothers

Table 2 .

 2 As expected, the neonates had lower PTH and higher corrected calcium levels compared with mothers. On the other hand, 25OHD,

	). None received vitamin D

VDBP, adiponectin and irisin] were compared according to the weeks of gestation (<37 vs. ≥37), maternal irisin levels were lower in the former group compared with the latter (153.3 vs. 402.5 ng/ml; p=0.006). When the median neonate weight (3205 g)

Table 8 .

 8 Maternal PTH levels were inversely correlated only with neonatal 25OHD levels. Maternal 25OHD levels were positively correlated with neonatal 25OHD and 1,25(OH) 2 D levels, and upper arm length. Maternal 1,25(OH) 2 D levels were inversely correlated with neonatal irisin levels and positively with abdominal skin fold. Maternal VDBP levels were inversely correlated with neonatal height and upper arm length, but not adiponectin or irisin levels. Maternal adiponectin levels were inversely correlated, albeit marginal, with neonatal weight. Maternal irisin levels were inversely correlated with neonatal 1,25(OH) 2 D levels and positively with knee-heel length.Notably, apart from 25OHD levels that were highly correlated between mothers and neonates, there was no correlation between maternal and neonatal levels of PTH, 1,25(OH) 2 D, VDBP, PTH, adiponectin and irisin (Table8).

	Neonatal adiponectin and irisin remained non-significantly associated with
	maternal VDPB, after sequential adjustment for weeks of gestation (model 1), weeks
	of gestation and maternal age (model 2), weeks of gestation, maternal age and BMI
	(term) (model 3), weeks of gestation and neonatal gender (model 4), weeks of
	gestation, neonatal gender and neonatal weight (model 5).

Since upper arm length was associated with both maternal and neonatal 25OHD and knee-heel length was associated with both maternal and neonatal irisin, we performed additional regression analyses with knee-heel length or upper arm length as dependent variables. Neonatal upper arm length remained significantly positively associated with maternal 25OHD after sequential adjustment for weeks of gestation (model 1), weeks of gestation and maternal age (model 2), weeks of gestation, maternal age and BMI (term) (model 3), and weeks of gestation, maternal age, BMI (term) and maternal VDBP (model 4; Table

9

). On the other hand, neonatal

Table 1 .

 1 Maternal and neonatal demographic and anthropometric characteristics.

	Maternal
	Number (n)

Table 2 .

 2 Comparative maternal and neonatal biochemical and hormonal parameters

		Mothers	Neonates	p-value *
	Corrected Calcium (mg/dl)	10.1 ± 0.1	11.7 ± 0.1	<0.001
	PTH (pg/ml)	27.2 ± 1.6	6.4 ± 0.2	<0.001
	25OHD (ng/ml)	18.3 ± 1.2	16.3 ± 1.0	0.217
	1,25(OH) 2 D (pg/ml)	51.9 ± 2.4	43.8 ± 3.6	0.057
	VDBP (μg/ml)	364.1 ± 11.9	355.3 ± 29.2	0.780
	Adiponectin (μg/ml)	4.4 ± 0.4	11.9 ± 2.0	<0.001
	Irisin (ng/ml) #	308.8 ± 50.8	174.4 ± 26.0	0.041
	Data are presented as mean ± standard error of the mean (SEM) for continuous
	variables.
	* Independent sample t-test or Mann-Whitney test were used for between group
	comparisons.
	# n=61 for mothers; n= 42 for neonates
	Abbreviations: 1,25(OH) 2 D, 1,25(OH) 2 -Vitamin D; 25OHD, 25(OH)-Vitamin D;
	PTH, parathyroid hormone; VDBP, Vitamin D-binding protein.

Table 3 .

 3 Correlations of maternal parameters.

		PTH	25ΟΗD	1,25(ΟΗ) 2 D	VDBP	Adiponectin	Irisin
		(pg/ml)	(ng/ml)	(pg/ml)	(μg/ml)	(μg/ml)	(ng/ml) #
	Age (years)	0.15 (0.22)	-0.08 (0.51)	-0.05 (0.68)	-0.26 (0.04)*	-0.23 (0.08)	-0.06 (0.64)
	Height (cm)	-0.08 (0.51)	0.26 (0.04)*	-0.17 (0.16)	0.10 (0.40)	-0.12 (0.35)	0.02 (0.83)
	Weight; pre-pregnancy (kg)	-0.06 (0.61)	0.09 (0.46)	0.06 (0.06)	-0.08 (0.51)	-0.21 (0.09)	0.13 (0.31)
	Weight; term (kg)	0.03 (0.81)	-0.01 (0.92)	0.01 (0.89)	-0.04 (0.73)	-0.28 (0.03)*	0.27 (0.047)*
	BMI; pre-pregnancy (kg/m 2 )	-0.08 (0.53)	0.03 (0.76)	0.11 (0.11)	-0.11 (0.39)	-0.17 (0.18)	0.10 (0.43)
	BMI; term (kg/m 2 )	-0.03 (0.83)	-0.07 (0.59)	0.01 (0.92)	-0.12 (0.33)	-0.27 (0.04)*	0.17 (0.21)
	Weeks of gestation (n)	-0.10 (0.49)	0.12 (0.41)	0.19 (0.19)	-0.14 (0.33)	0.05 (0.72)	0.28 (0.06)
	Corrected calcium (mg/dl)	-0.46 (<0.001)*	0.38 (0.002)*	0.28 (0.002)*	0.13 (0.28)	-0.07 (0.55)	-0.02 (0.85)
	PTH (pg/ml)	-	-0.46 (<0.001)*	0.00 (0.97)	-0.03 (0.77)	0.17 (0.15)	0.10 (0.43)
	25(ΟΗ)D (ng/ml)	-	-	0.49 (<0.001)*	0.01 (0.92)	0.10 (0.39)	0.00 (0.98)
	1,25(ΟΗ) 2 D (pg/ml)	-	-	-	0.21 (0.07)	0.08 (0.51)	0.25 (0.05)
	VDBP (μg/ml)	-	-	-	-	0.41 (0.001)*	0.30 (0.02)*

*: Statistically significant correlation. # n=61 Abbreviations: 1,25(OH) 2 D, 1,25(OH) 2 -Vitamin D; 25OHD, 25(OH)-Vitamin D; BMI, body mass index; PTH, parathyroid hormone; VDBP, Vitamin D-binding protein.

Table 6 .

 6 Correlations of neonatal parameters.

	PTH	25(ΟΗ)D	1,25(ΟΗ) 2 D	VDBP	Adiponectin	Irisin
	(pg/ml)	(ng/ml)	(pg/ml)	(μg/ml)	(μg/ml)	(ng/ml) #

*: Statistically significant correlation # n=42 Abbreviations: 1,25(OH) 2 D, 1,25(OH) 2 -Vitamin D; 25OHD, 25(OH)-Vitamin D; PTH, parathyroid hormone; VDBP, Vitamin D-binding protein.

Table 8 .

 8 Correlations between maternal and neonatal parameters.

	Maternal parameters

Data are presented as Spearman's correlation (p-value). *: Statistically significant correlation # n=61 for mothers; N= 42 for neonates Abbreviations: 1,25(OH) 2 D, 1,25(OH) 2 -Vitamin D; 25OHD, 25(OH)-Vitamin D; PTH, parathyroid hormone; VDBP, Vitamin D-binding protein.

Table 4 .

 4 Sequential models of linear logistic regression analysis evaluating independent associates of maternal adiponectin levels (μg/ml).

		Unstandardized	Standardized		95% CI for
	Variable			p-value
		β	β		β
	Model 1
	Maternal VDBP (μg/ml)	0.02	0.41	0.005	0.01 -0.03
	Weeks of Gestation	1.01	0.14	0.31	-0.92 -2.97
	Model 2
	Maternal VDBP (μg/ml)	0.02	0.38	0.011	0.01 -0.03
	Weeks of Gestation	1.00	0.15	0.29	-0.92 -3.00
	Maternal age (years)	-0.07	-0.14	0.34	-0.22 -0.08
	Model 3
	Maternal VDBP (μg/ml)	0.02	0.35	0.026	0.01 -0.03
	Weeks of Gestation	0.74	0.10	0.47	-1.32 -2.80
	Maternal age (years)	-0.04	-0.07	0.64	-0.21 -0.13
	Maternal BMI; term
		-0.07	-0.15	0.33	-0.23 -0.08
	(kg/m 2 )

Disclosure statement:

The authors have nothing to disclose. Weeks of gestation was rated as 0 for <38, and 1 for ≥38, respectively.

# n=61 for mothers

Abbreviations: VDBP, Vitamin D-binding protein. Weeks of gestation was rated as 0 for <38, and 1 for ≥38, respectively.

Boys were rated as 0, and girls as 1 within gender.

Abbreviations: VDBP, Vitamin D-binding protein. Weeks of gestation was rated as 0 for <38, and 1 for ≥38, respectively.

Abbreviations: 25OHD, 25(OH)-Vitamin D; VDBP, Vitamin D-binding protein.


Dimitrios Kapogiannis

E L Haj

Mohamad El Haj
email: mohamad.elhaj@univ-lille3.fr.

Beneficial effect of minimal interference on item memory but not on source memory in Alzheimer's disease

Keywords: Alzheimer's disease, hippocampus, memory, memory rehabilitation, minimal interference, source memory

Objectives: research suggests beneficial effects of minimal interference on item memory in mild Alzheimer's disease (AD). We conducted a study to test whether these beneficial effects extend to source memory, i.e., the ability to remember the episodic context in which an information was previously acquired.

Methods: twenty-six mild AD participants and 28 controls manipulated six objects or watched the experimenter manipulating six other objects. After immediate item recall ("what were the items?") and source recall ("by whom the items were previously manipulated?"), an interference or a minimal interference condition was administrated. In the interference condition, participants were assessed with neuropsychological tests for 10 min. In the minimal interference condition, they rested alone in a dark and quiet room for 10 minutes. Both interference and minimal interference conditions were followed by delayed recall, on which participants were asked to remember the previously-presented objects and their source.

Results: Higher item memory was observed following minimal interference than following interference in AD participants (p < .01) and controls (p < .01). Also, AD participants demonstrated higher item memory on immediate recall than following interference (p < .001) or minimal interference (p < .001); controls also demonstrated higher item memory on immediate recall than following interference (p < .001) or minimal interference (p < .001). Considering source memory, similar source memory was observed following interference and minimal interference in AD participants (p > .1) and controls (p > .1). Also, AD participants demonstrated higher source memory on immediate recall than following interference (p < .001) or minimal interference (p < .001); controls also demonstrated higher source memory on immediate recall than following interference (p < .001) or minimal interference (p < .001).

Introduction

Alzheimer's disease (AD) is a progressive age-related neurodegenerative disease involving insidiously progressive episodic memory impairment [START_REF] Mckhann | The diagnosis of dementia due to Alzheimer's disease: recommendations from the National Institute on Aging-Alzheimer's Association workgroups on diagnostic guidelines for Alzheimer's disease[END_REF]. The disease is characterized by the accumulation of amyloid-beta (Aβ) deposits extracellularly and development of neurofibrillary tangles containing tau intracellularly [START_REF] Mckhann | The diagnosis of dementia due to Alzheimer's disease: recommendations from the National Institute on Aging-Alzheimer's Association workgroups on diagnostic guidelines for Alzheimer's disease[END_REF]. AD-related episodic memory decline is specifically associated with these neuropathological changes in entorhinal cortex and other medial temporal lobe structures. The medial temporal lobe also includes the hippocampus, a brain structure critical for all forms of declarative memory that shows prominent functional dysfunction and structural compromise by the disease [START_REF] Pennanen | Hippocampus and entorhinal cortex in mild cognitive impairment and early AD[END_REF].

One of the earliest features of episodic memory impairment in AD is anterograde amnesia (i.e., inability to form new memories), a difficulty that is usually followed by retrograde amnesia (i.e., inability to retrieve old memories) [START_REF] Mckhann | The diagnosis of dementia due to Alzheimer's disease: recommendations from the National Institute on Aging-Alzheimer's Association workgroups on diagnostic guidelines for Alzheimer's disease[END_REF][START_REF] Haj | Autobiographical memory decline in Alzheimer's disease, a theoretical and clinical overview[END_REF]. The memory decline in AD also results in difficulties performing basic activities of daily living (e.g., problems in remembering to take medications or to turn off the oven), disorientation in time and space (e.g., difficulties to remember date-related information or the way back home), and, in the advanced stages of the disease, difficulties remembering basic information such as the subject's own name [START_REF] Mckhann | The diagnosis of dementia due to Alzheimer's disease: recommendations from the National Institute on Aging-Alzheimer's Association workgroups on diagnostic guidelines for Alzheimer's disease[END_REF]. Considering the devastating effects of memory decline in AD, clinical research aims to assess the efficiency of rehabilitation interventions that may alleviate this decline, and one prominent candidate of an intervention is minimal interference.

Research on minimal interference suggests that a brief wakeful rest after new learning may enhance memory for the learned material, an observation that was reported even in patients with severe amnesia [START_REF] Cowan | Verbal recall in amnesiacs under conditions of diminished retroactive interference[END_REF][START_REF] Dewar | Profound retroactive interference in anterograde amnesia: What interferes?[END_REF]. The beneficial effect of minimal interference was also observed in patients with mild cognitive impairment [START_REF] Dewar | Delaying interference enhances memory consolidation in amnesic patients[END_REF], and patients with mild AD [START_REF] Dewar | Insights into spared memory capacity in amnestic MCI and Alzheimer's Disease via minimal interference[END_REF]. In a pioneering study on minimal interference [START_REF] Cowan | Verbal recall in amnesiacs under conditions of diminished retroactive interference[END_REF], six patients with severe amnesia due to anoxia, head injury, limbic encephalitis, or stroke, were presented with lists of words, which they had to recall immediately afterwards, as well as following a 10 min delay. During this delay, participants either engaged in neuropsychological assessment (an "interference condition"), or rested alone in a dark and quiet testing room (a "minimal interference condition"). Although two of the six patients were unable to recall any of the words in either condition, four patients showed higher recall of the words following the minimal interference (49% of correct recall) than the interference condition (14% of correct recall). Benefits were also observed in healthy controls, whose mean percentage recall were 74% and 46% in the minimal interference and interference conditions respectively. Considering these outcomes, the authors [START_REF] Cowan | Verbal recall in amnesiacs under conditions of diminished retroactive interference[END_REF] conducted a second study of potential benefits of minimal interference for longer delay. The same participants were presented with sentences, and the interference and minimal interference conditions were extended to one hour instead of 10 minutes. Similarly to the first experiment, four of the six patients benefited significantly from the minimal interference (79% of correct recall) than from the interference condition (7% of correct recall). Benefits were also observed in the healthy controls, whose mean percentage recall was 89% and 79% in the minimal interference and interference conditions respectively. Regarding AD, Dewar, Pesallaccia [START_REF] Dewar | Insights into spared memory capacity in amnestic MCI and Alzheimer's Disease via minimal interference[END_REF] presented mild AD participants with lists of words, which they had to recall immediately afterwards as well as following a 10 min delay, a delay during which participants either engaged in a picture naming task, or rested alone in a dark and quiet testing room. These procedures showed higher word recall following the minimal interference than following the interference condition.

If minimal interference improves item memory in AD [START_REF] Dewar | Insights into spared memory capacity in amnestic MCI and Alzheimer's Disease via minimal interference[END_REF], then it would be of interest to investigate whether such an effect is also seen for a memory facet that is particularly vulnerable in AD, namely, source memory. Source memory refers to the ability to remember the episodic context in which an information was previously acquired (e.g., "where I met that person before?") [START_REF] Johnson | Source monitoring[END_REF]. Unlike item memory, source memory is compromised in normal aging [START_REF] Spencer | Differential effects of aging on memory for content and context: a metaanalysis[END_REF][START_REF] Spencer | Memory for facts, source, and context: can frontal lobe dysfunction explain age-related differences?[END_REF][START_REF] Haj | Relationship between source monitoring in episodic memory and executive function in normal aging[END_REF], although less so. Studies have shown source memory decline when AD participants are asked to remember whether words were previously generated by themselves or by the experimenter [START_REF] Multhaup | Generation effects and source memory in healthy older adults and in adults with dementia of the Alzheimer type[END_REF], whether actions were previously enacted or imagined [START_REF] Fairfield | The role of cognitive operations in reality monitoring: a study with healthy older adults and Alzheimer's-type dementia[END_REF], or whether drawings of objects were previously imagined or perceived [START_REF] Barba | Confabulation, executive functions, and source memory in Alzheimer's Disease[END_REF] ((for a review, see, [START_REF] El Haj | Context Memory in Alzheimer's Disease[END_REF]). In a study assessing source memory with several tasks, mild AD participants were asked to remember 1) whether objects were previously manipulated with a black or white glove, 2) whether objects were previously manipulated by the participants or by the experimenter, or 3) whether objects were previously imagined or manipulated by the participants [START_REF] El Haj | Source monitoring in Alzheimer's disease[END_REF]. Results showed poorer source memory in AD participants than in healthy controls across the three conditions. For both populations, poorer source memory was observed in the third than in the second condition, and in the second than in the first condition.

Potential beneficial effects of minimal interference on memory in AD may be attributable to its effects on consolidation processes. Memory consolidation refers to the progressive postacquisition stabilization of long-term memories [START_REF] Dudai | Neurobiology of Consolidations, Or, How Stable is the Engram?[END_REF]. Findings from animal and human studies suggest that wakeful resting enhances recall by allowing for better memory consolidation. For instance, in animals, sequential neural activation associated with recent learning (e.g., exploring a new maze) was found to be replayed during wakeful resting [START_REF] Carr | Hippocampal replay in the awake state: a potential substrate for memory consolidation and retrieval[END_REF][START_REF] Foster | Reverse replay of behavioural sequences in hippocampal place cells during the awake state[END_REF]. This consolidation process was found to be prone to interference during pharmacological manipulations, such as injection of toxins, drugs and seizures [START_REF] Dudai | Neurobiology of Consolidations, Or, How Stable is the Engram?[END_REF]. In particular, pronounced detrimental effects were observed when the interference occurred immediately after learning, an interval during which newly acquired memory traces may be still weak and in need of strengthening [START_REF] Dudai | Neurobiology of Consolidations, Or, How Stable is the Engram?[END_REF]. Further evidence for the beneficial effect of resting on memory consolidation comes from neuroimaging human studies suggesting that sleep supports the consolidation of newly acquired memories [START_REF] Rauchs | Autonoetic consciousness in Alzheimer's disease: Neuropsychological and PET findings using an episodic learning and recognition task[END_REF].

The present study was designed to address the hypothesis that source memory decline in mild AD may be alleviated by minimal interference, similar to its beneficial effect on item memory [START_REF] Dewar | Insights into spared memory capacity in amnestic MCI and Alzheimer's Disease via minimal interference[END_REF]. To distinguish between potential beneficial effect of minimal interference on item and source memory in AD, we administrated a source memory task on which AD patients have previously shown lesser decline [START_REF] El Haj | Source monitoring in Alzheimer's disease[END_REF]. Specifically, AD and control participants were asked to manipulate items or to watch the experimenter do so. After immediate item recall ("what were the items"?) and source recall ("by whom the items were previously manipulated?"), participants either engaged in 10 min of neuropsychological testing, or rested alone for the same amount of time, followed by testing of item and source recall. We hypothesized that similar beneficial effects of minimal interference for item memory would be seen in both groups, but that any effects for source memory would be less pronounced in AD compared to control participants, given its heavier dependence on hippocampal processes [START_REF] Cohen | Hippocampal system and declarative (relational) memory: summarizing the data from functional neuroimaging studies[END_REF][START_REF] Eichenbaum | The medial temporal lobe and recognition memory[END_REF].

Method

Participants

We tested 26 participants at the mild stage of AD and 28 healthy control participants. The AD participants were recruited from two local retirement homes and were diagnosed with probable AD dementia by an experienced neurologist or geriatrician based on the National Institute on Aging-Alzheimer's Association clinical criteria [START_REF] Mckhann | The diagnosis of dementia due to Alzheimer's disease: recommendations from the National Institute on Aging-Alzheimer's Association workgroups on diagnostic guidelines for Alzheimer's disease[END_REF]. The control participants were spouses or relatives of the AD participants, or were members of a local association promoting activities in retirement homes. Controls were functionally independent and living in their own homes. As showed in Table 1, controls were matched with the AD participants according to age, sex, and educational level. Exclusion criteria for all participants were: significant psychiatric or neurological illness other than AD, and alcohol or drug abuse. All participants presented no major visual or auditory acuity difficulties that would have prevented completion of study tasks. All participants provided informed consent. Two AD participants withdrew from the study for health problems without providing any research data (original AD sample, n = 28 participants).

Cognitive and clinical assessment.

-We administered tests assessing general cognitive functioning, episodic memory, working memory, verbal fluency, inhibition, and depression. All scores are shown in Table 1. [START_REF] Folstein | Mini-mental state". A practical method for grading the cognitive state of patients for the clinician[END_REF], and the maximum score was 30 points. Episodic memory was evaluated with the task of Grober and Buschke [START_REF] Grober | Genuine memory deficits in dementia[END_REF]. The participants had to retain 16 words, and after immediate cued recall, they proceeded to a 20-seconds distraction phase during which they had to count numbers aloud. This phase was followed by two minutes of free recall and the score from this phase (out of a maximum of 16) was retained as episodic score. For working memory assessment, participants had to repeat a string of single digits in the same order (i.e., forward span) or in the inverse order (i.e., backward span) [START_REF] Wechsler | Adult Intelligence Scale 4th Ed[END_REF]. On the verbal fluency task, participants were given two minutes to generate as many words beginning with the letter P, proper names and variants of the same words were not taken into account. Inhibition was evaluated with the Stroop task [START_REF] Stroop | Studies of interference in serial verbal reactions[END_REF], and the score referred to the completion time (in seconds) for the interference condition minus the average completion time for word reading and color naming. Depression was assessed with the self-report Hospital Anxiety and Depression Scale [START_REF] Zigmond | The Hospital Anxiety and Depression Scale[END_REF] consisting of seven items scored on a four-point Likert scale from zero (not present) to three (considerable). The maximum score was 21 points and the cut-off for definite depression was set at > 10/21 points ((for more details on the cognitive and clinical assessment, see [START_REF] Haj | Similarity between remembering the past and imagining the future in Alzheimer's disease: Implication of episodic memory[END_REF][START_REF] Haj | Flexibility decline contributes to similarity of past and future thinking in Alzheimer's disease[END_REF]); in line with a large body of evidence, [START_REF] Ownby | Depression and risk for Alzheimer disease: systematic review, meta-analysis, and metaregression analysis[END_REF][START_REF] Quattropani | The origin of depression in Alzheimer disease: a systematic review[END_REF], higher depressions scores were observed in AD patients than in controls.

General cognitive functioning was assessed with the Mini Mental State Exam

Procedures

Controls and AD participants were tested individually in quiet testing rooms at two retirement homes. The experiments took place over two sessions, spaced one week apart on average. In the first session, participants were assessed with a source memory task on which they were exposed to a set of 12 everyday-life objects (e.g., clothespin, candle, shoelace, paintbrush, chisel, spoon). Objects corresponded to medium-to high-frequency words, they were carefully selected to be normal-sized and without distinctive features, and were taken from a large pool used by previous studies assessing source memory [START_REF] Haj | Relationship between source monitoring in episodic memory and executive function in normal aging[END_REF][START_REF] El Haj | Source monitoring in Alzheimer's disease[END_REF][START_REF] Haj | What do we know about the relationship between source monitoring deficits and executive dysfunction?[END_REF][START_REF] El Haj | Destination and source memory in Huntington's disease[END_REF][START_REF] El Haj | Source monitoring in Korsakoff's syndrome: "Did I touch the toothbrush or did I imagine doing so?[END_REF].

Prior to the source memory task, participants were clearly instructed that they had to remember whether the objects were manipulated by themselves or by the experimenter, and that they would be asked about this immediately afterwards. No mention of a delayed recall phase was made. The objects were successively presented on a table, and participants were asked to name each object. Afterward, participants were asked either to insert the object in a black bag placed on the table or to watch the experimenter do so. Half of the 12 objects were pre-randomized to be inserted in the bag by the experimenter, whereas the other half were pre-randomized to be inserted in the bag by the participants. This order was predetermined and displayed on a grid so that the experimenter could easily carry out the task. Next, participants were asked to remember the objects in any order (i.e., immediate item memory), and for each object, they were asked to remember whether it had been originally inserted in the bag by themselves or by the experimenter (i.e., immediate source memory).

The immediate item and source memory recall was followed by 10 min during which their spans, verbal fluency, and depression scores were assessed in the same order for all participants. When the assessment exceeded 10 min, the tasks were interrupted and were resumed later (after the delayed recall). After the 10-minute delay, participants were asked to remember the previously-presented objects in any order (i.e., delayed item memory), and for each object, they were asked to remember whether it had been originally inserted in the bag by themselves or by the experimenter (i.e., delayed source memory).

Procedures were replicated in the second session, with two exceptions. A second set of object was administrated in the source memory task, and more critically, during the 10 min delay, participants rested alone in the testing room. Following immediate item and source recall, participants were informed that the experimenter would be leaving the testing room for several minutes in order to prepare the next task, and that he would dim the lights. Participants were instructed to sit back and rest until the return of the experimenter who subsequently left the room, returning 10 min later. When the experimenter returned, testing of delayed item and source memory took place.

It should be noted that the two sessions were counterbalanced across participants. Item memory performance refers to percentage of correctly recalled items. Source memory performance refers to percentage of correctly recalled sources of the correctly recalled items

Results

Results are depicted in Table 2. Prior to performing analyses, all variables were plotted and checked for normal distribution with the Shapiro-Wilk test that showed that the assumption of normality was not met. Thus, non-parametric tests were used; Wilcoxon signed rank-sum tests were used for within-group comparisons, and Mann-Whitney U tests were used for between-group comparisons. For all tests, the level of significance was set as p ≤ 0.05, whereas p values between 0.051 and 0.10 were considered as trends. Results were provided with the observed power: d = .2 can be considered a small effect size, d = .5 represents a medium effect size and d = .8 refers to a large effect size [START_REF]Cohen J Statistical power analysis for the behavioral sciences[END_REF]. Note that Cohen's d was calculated for non-parametric tests following the recommendations by Rosenthal and DiMatteo [START_REF] Rosenthal | Meta-analysis: recent developments in quantitative methods for literature reviews[END_REF], and Ellis (36).

Higher item memory after minimal interference than after interference.

-For AD participants, item memory was higher on immediate recall than following interference (Z = -4.20, p < .001, Cohen's d = 2.90) or minimal interference (Z = -3.67, p < .001, Cohen's d = 2.07). Interestingly, item memory was higher following minimal interference than following interference (Z = -2.62, p < .01, Cohen's d = 1.20). The same outcomes were observed for controls. Item memory was higher on immediate recall than following interference (Z = -4.31, p < .001, Cohen's d = 2.81) or minimal interference (Z = -3.63, p < .001, Cohen's d = 1.88). Item memory was higher following minimal interference than following interference (Z = -2.58, p < .01, Cohen's d = 2.07).

Similar source memory after interference and minimal interference.-

For AD participants, source memory was higher on immediate recall than following interference (Z = -4.22, p < .001, Cohen's d = 2.94) or minimal interference (Z = -4.32, p < .001, Cohen's d = 3.19). However, similar source memory was observed following interference and minimal interference (Z = -1.01, p > .1, Cohen's d = .40). The same outcomes were observed for controls. Source memory was higher on immediate recall than following interference (Z = -4.17, p < .001, Cohen's d = 2.56) or minimal interference (Z = -3.96, p < .001, Cohen's d = 2.25). Similar source memory was observed following interference and minimal interference (Z = -.80, p > .1, Cohen's d = .31). We examined the potential effects of the order of assessment (interference vs. minimal interference) and found no significant effects on delayed item and source memory in in AD patients (p > .1) or controls (p > .1).

Low item and source memory in AD-

Discussion

In light of research suggesting beneficial effects of minimal interference on item memory in AD, the present study investigated whether source memory may also benefit from this condition. By assessing item and source memory during immediate recall and following interference and minimal interference, we showed beneficial effects of minimal interference for item but nor for source memory in mild AD.

Replicating the findings of Dewar, Pesallaccia [START_REF] Dewar | Insights into spared memory capacity in amnestic MCI and Alzheimer's Disease via minimal interference[END_REF] our study showed beneficial effects of minimal interference for item memory in mild AD. Our findings are also in agreement with previous research in patients with severe amnesia [START_REF] Cowan | Verbal recall in amnesiacs under conditions of diminished retroactive interference[END_REF][START_REF] Dewar | Profound retroactive interference in anterograde amnesia: What interferes?[END_REF] and mild cognitive impairment [START_REF] Dewar | Delaying interference enhances memory consolidation in amnesic patients[END_REF]. Regarding control participants, beneficial effects of minimal interference were also observed, in agreement with a study in which healthy older adults were presented with two stories, and one was followed by interfering tasks for 10 min, while the other one was followed by a 10 min delay of wakeful resting [START_REF] Dewar | Brief wakeful resting boosts new memories over the long term[END_REF]. Results showed that minimal interference led to significant enhancement of memory after minimal interference. Hence, a brief wakeful rest after item learning may enhance item memory in both AD and normal aging, at least for short delays. Disappointingly, unlike item memory, source memory did not benefit from minimal interference in either AD or control participants. A possible explanation may be that the agerelated source memory compromise that is shared by both groups may not be amenable to improvement by behavioral interventions. Indeed, we showed much poorer source memory than item memory in both populations, regardless the experimental condition. These outcomes also mirror previous research, suggesting source memory impairment in normal aging [START_REF] Spencer | Memory for facts, source, and context: can frontal lobe dysfunction explain age-related differences?[END_REF][START_REF] Haj | Relationship between source monitoring in episodic memory and executive function in normal aging[END_REF][START_REF] El Haj | Source monitoring in Korsakoff's syndrome: "Did I touch the toothbrush or did I imagine doing so?[END_REF] and AD [START_REF] Multhaup | Generation effects and source memory in healthy older adults and in adults with dementia of the Alzheimer type[END_REF][START_REF] Barba | Confabulation, executive functions, and source memory in Alzheimer's Disease[END_REF][START_REF] El Haj | Source monitoring in Alzheimer's disease[END_REF][START_REF] Fairfield | The role of cognitive operations in reality monitoring: a study with healthy older adults and Alzheimer's-type dementia[END_REF][START_REF] El Haj | Directed forgetting of source memory in normal aging and Alzheimer's disease[END_REF].

The associative nature of source memory may also account for the absence of a beneficial effect of minimal interference. Unlike item memory, source memory requires associative processes linking the targeted item (e.g., a given face) to its learning context (e.g., where I met this face before), and these associative processes are found to be compromised in normal aging [START_REF] Bastin | Associative memory in aging: the effect of unitization on source memory[END_REF] and AD [START_REF] Bastin | Associative memory and its cerebral correlates in Alzheimers disease: evidence for distinct deficits of relational and conjunctive memory[END_REF]. These associative processes draw heavily on hippocampal resources. Hippocampal lesions in animals typically show preservation of short-term item memory, but result in consistent and profound deficits in memory for relational representations [START_REF] Olsen | The hippocampus supports multiple cognitive processes through relational binding and comparison[END_REF]. In a related vein, amnesic patients with hippocampal damage show greater deficits in source than in item memory [START_REF] Mayes | Associative memory and the medial temporal lobes[END_REF]. Associative processes in the hippocampus imply binding or linking of disparate elements, each of which are stored separately within the cortex, into coherent representations [START_REF] Cohen | Hippocampal system and declarative (relational) memory: summarizing the data from functional neuroimaging studies[END_REF][START_REF] Eichenbaum | The medial temporal lobe and recognition memory[END_REF]. The hippocampus is not only implied in the integration and formation of associative representations, but also in comparisons of these representations to current perceptual input and/or previously stored representations, a comparison that is found to be mediated by the CA1 [START_REF] Olsen | The hippocampus supports multiple cognitive processes through relational binding and comparison[END_REF]. According to Olsen, Moses [START_REF] Olsen | The hippocampus supports multiple cognitive processes through relational binding and comparison[END_REF], these associative and comparison processes are intimately intertwined; as soon as perceptual input reaches the hippocampus, the associative processes begin and the output of that binding is compared to the relevant representations stored in memory. Since these comparative and associative processes are required for source memory and these processes are profoundly impaired in both normal aging and AD, mild physiologic interventions, such as minimal interference, may be unable to exert any measurable benefits.

Considering source memory, we found lower source memory in AD participants than in controls for immediate recall, interference, and minimal interference. These findings demonstrate negative effects of AD on source memory. These negative effects can be associated with several cognitive and clinical symptoms of AD, such as false memories and confabulations. Past research has documented relationships between source memory distortions and false memories in AD. More specifically, previous studies have shown a relationship between source memory distortions in AD and false alarms, i.e., incorrect statements by patients that a novel context had been encountered previously [START_REF] El Haj | Source monitoring in Alzheimer's disease[END_REF][START_REF] Goldman | Source memory in mild to moderate Alzheimer's disease[END_REF][START_REF] Pierce | Comparing source-based and gist-based false recognition in aging and Alzheimer's disease[END_REF][START_REF] Mammarella | Comparing different types of source memory attributes in dementia of Alzheimer's type[END_REF]. Source memory distortions have been also associated with difficulties in AD patients in distinguishing between enacted and imagined events [START_REF] El Haj | Source monitoring in Alzheimer's disease[END_REF][START_REF] O'connor | The imagination inflation effect in healthy older adults and patients with mild Alzheimer's disease[END_REF]. Also, source memory distortions have been associated with confabulations, false memories without the intent to deceive [START_REF]El Haj M Memory suppression in Alzheimer's disease[END_REF][START_REF] Kopelman | Varieties of confabulation and delusion[END_REF]. A study reported a relationship between confabulations AD and difficulties in attribution of the origin of memories (i.e., source memory); according to this study, AD patients who confabulate misattribute features of an event that occurred at one time to another event that occurred at another time [START_REF] Noel | Confabulations and consciousness in Alzheimer's disease[END_REF] (for a similar account, see [START_REF] Schnider | Spontaneous confabulations, disorientation, and the processing of 'now[END_REF][START_REF] Barba | Confabulation: Remembering 'another' past, planning 'another' future[END_REF][START_REF] Barba | Autobiographical memory loss and confabulation in Korsakoff's syndrome: a case report[END_REF]).

Studies on minimal interference suggest that wakeful resting after learning allows new memory traces to be consolidated better and hence to be retained for much longer [START_REF] Dewar | Profound retroactive interference in anterograde amnesia: What interferes?[END_REF][START_REF] Dewar | Delaying interference enhances memory consolidation in amnesic patients[END_REF][START_REF] Dewar | Insights into spared memory capacity in amnestic MCI and Alzheimer's Disease via minimal interference[END_REF][START_REF] Dewar | Brief wakeful resting boosts new memories over the long term[END_REF]. Animal studies suggest that firing sequences observed in hippocampal ensembles during learning are found to be replayed during subsequent sleep [START_REF] Carr | Hippocampal replay in the awake state: a potential substrate for memory consolidation and retrieval[END_REF]. In human studies, hippocampal areas that are found to be activated during learning are likewise activated during subsequent slow wave sleep [START_REF] Peigneux | Are spatial memories strengthened in the human hippocampus during slow wave sleep?[END_REF]. Hence, the hippocampus plays a pivotal role in memory consolidation during resting. The beneficial effects of minimal interference for item memory we and others found imply that some hippocampus-dependent consolidation processes may be preserved in AD, at least enough to enhance item memory and/or for short delays.

It is possible that the beneficial effect of minimal interference on item memory might result from conscious rehearsal than from unconscious consolidation processes. In other words, when were alone, our participants might have rehearsed the items, an opportunity they missed in the interference condition, and this might have produced the beneficial effect of minimal interference on item memory. Even though this possibility cannon be entirely ruled out, we were careful not to mention any delayed recall, in order to minimize their motivation to engage in conscious rehearsal.

Our results suggest that mild AD patients demonstrate some capacity to consolidate new information. It would be of interest to investigate whether this effect can be observed for longer delays. A prominent venue for investigation is sleep. Consolidation is believed to mainly occur during slow wave sleep, which strengthens the newly-acquired memories and makes them more resistant to interference [START_REF] Peigneux | Are spatial memories strengthened in the human hippocampus during slow wave sleep?[END_REF][START_REF] Born | Sleep to remember[END_REF]. It would be of interest to investigate whether sleep may enhance item memory, and even, source memory in mild AD. The same suggestion can be made for healthy older adults and patients with mild cognitive impairment, as past research has demonstrated that sleep disruption may contribute to memory impairment in normal aging [START_REF] Westerberg | Memory improvement via slow-oscillatory stimulation during sleep in older adults[END_REF][START_REF] Mander | Sleep and Human Aging[END_REF][START_REF] Varga | Effects of aging on slowwave sleep dynamics and human spatial navigational memory consolidation[END_REF] and mild cognitive impairment [START_REF] Westerberg | Concurrent impairments in sleep and memory in amnestic mild cognitive impairment[END_REF][START_REF] Westerberg | Sleep influences the severity of memory disruption in amnestic mild cognitive impairment: results from sleep self-assessment and continuous activity monitoring[END_REF].

In everyday life, learning is almost invariably followed by further information or activity that interfere with the learned material. The same applies to assessments in memory clinics, where AD patients deal with new materials as soon as they are presented with a set of stimuli. As demonstrated by the present study, whether delay between learning and recall is filled or not with activity may influence recall in AD patients. AD patients may show some capacity to retain new material, should the material presentation be followed by short delays that are free of further stimuli. While AD patients demonstrate some benefit of minimal interference for item memory, no such benefit is observed for source memory, which may be considered as a limitation to the usefulness of minimal interference in the disease. These findings are worth considering by clinicians, caregivers and care facilities who provide care to patients with AD who may allow for regular periods of minimal interference to enhance memory performance. In addition, these findings are also valuable for clinical researchers who typically assess memory in AD patients in the setting of multi-faceted clinical studies that include multiple tests and experimental procedures. Such settings may be compromising to the fragile memory of AD patients and lead researchers to underestimate the patients' true cognitive performance. Curr Alzheimer Res. Author manuscript; available in PMC 2019 January 01.

  Lower item memory was observed in AD participants than in controls for immediate recall (Z = -4.68, p < .001, Cohen's d = 1.65), interference (Z = -4.82, p < .001, Cohen's d = 1.72), and minimal interference (Z= -4.71, p < .001, Cohen's d = 1.67). Lower source memory was also observed in AD participants than in controls for immediate recall (Z = -3.97, p < .001, Cohen's d = 1.16), interference (Z = -4.41, p < .001, Cohen's d = 1.43), and minimal interference (Z = -4.73, p < .001, Cohen's d = 1.68).Regarding AD participants, higher item than source memory was observed for immediate recall (Z = -4.36, p < .001, Cohen's d = 4.33), interference (Z = -2.57, p < .01, Cohen's d = 1.17), and minimal interference (Z = -4.10, p < .001, Cohen's d = 2.70). Regarding controls, higher item than source memory was observed for immediate recall (Z = -4.49, p < .001, Cohen's d = 3.23), interference (Z = -4.33, p < .001, Cohen's d = 3.11), and minimal interference (Z = -4.35, p < .001, Cohen's d = 3.16).

Table 1 .

 1 Demographic, cognitive, and clinical characteristics of Alzheimer's disease (AD) and control participants Note. Standard deviations are given between brackets; performance on the Mini-Mental State Examination referred to correct responses/30; performance on the Grober and Buschkle's task referred to correct responses/16; performance on the forward and backward spans referred to number of correctly repeated digits; performance on verbal fluency referred to the number of correctly generated words; inhibition score referred to completion time in sec; the maximum score on depression scale was 21 points; n/s differences between groups were non-significant; differences between groups were significant at *

	AD	Controls
	n = 26	n = 28

** p < .001, *** p < .001; gender differences was compared with Chi-square test; comparisons for remaining variables were established with Mann-Whitney's U test (abnormal distribution), except for fluency that was compared with Student's t-test (normal distribution).

Curr Alzheimer Res. Author manuscript; available in PMC 2019 January 01.

Table 2 .

 2 Item memory and source memory on immediate recall and following interference and minimal interference in Alzheimer's disease (AD) and control participants Note. Standard deviations are given between brackets; performance referred to percentage of correct responses.

		AD	Controls
		Item memory
	Immediate recall	46.79 (11.80) 67.86 (13.36)
	Interference	18.91 (14.44) 41.07 (11.09)
	Minimal interference 29.81 (11.34) 50.00 (13.03)
		Source memory
	Immediate recall	31.09 (8.68)	47.32 (16.34)
	Interference	9.62 (8.40)	23.21 (9.80)
	Minimal interference 10.90 (7.73)	25.90 (10.72)

Curr Alzheimer Res. Author manuscript; available in PMC 2019 January 01.

Acknowledgments

Dr. Kapogiannis was supported by the Intramural Research Program of the National Institute on Aging, NIH. Dr. El Haj, was supported by the LABEX (excellence laboratory, program investment for the future) DISTALZ (Development of Innovative Strategies for a Transdisciplinary approach to Alzheimer disease) and the EU Interreg 2 Seas Programme 2014-2020 (co-funded by the European Regional Development Fund).