Sylvain Clède

François Lambert

Christophe Sandt

Zoher Gueroui

Matthieu Réfrégiers

Marie-Aude Plamont

Paul Dumas

Anne Vessières

Clotilde Policar
email: clotilde.policar@ens.fr

A rhenium tris-carbonyl derivative as a

Keywords: cell culture, fluorescent organelle staining, nature of the slides, cells incubation for FTIR on a collection of cells, fluorescence imaging, synchrotron radiation FTIR and UV spectromicroscopies, FTIR, UV

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

A rhenium tris-carbonyl derivative as a single core multimodal probe for imaging (SCoMPI) combining infrared and luminescent propertiesw Sylvain Cle`de, abc Franc¸ois Lambert, abc Christophe Sandt, d Zoher Gueroui, abe Matthieu Re´fre´giers, d Marie-Aude Plamont, f Paul Dumas, d Anne Vessie`res f and Clotilde Policar* abc A rhenium tris-carbonyl derivative has been designed to couple infrared and luminescent detection in cells. Both spectroscopies are consistent with one another; they point out the reliability of the present SCoMPI (for Single Core Multimodal Probe for Imaging) for bimodal imaging and unambiguously indicate a localization at the Golgi apparatus in MDA-MB-231 breast cancer cells.

The variety of biological issues imposes the use of a wide range of techniques to understand and rationalize intricate biomolecular mechanisms. In this context, bio-imaging techniques are pivotal since they allow direct visualization of labelled biomolecules or organelles. Molecules or tags that can be detected by several complementary techniques offer possibilities of crosscorrelative comparisons. [1][2][3] Elaborate molecules showing dual properties, such as fluorescence and magnetic resonance 4 or fluorescence and radio emission, 5 have been designed and used as efficient reporters for cell and animal imaging. However, these derivatives are mostly multiple core entities where each covalently bound fragment plays a unique spectroscopic, magnetic or radioactive role, 6 and whose large size is likely to modify the physico-chemical properties of the tagged molecule.

Fluorescence microscopy is a powerful, widespread technique for cell imaging. Many fluorophores are commercially available for organelle staining and biomolecule tagging. Turnkey filter-cubes adaptable to a large set of molecules allow quick and efficient detection of UV-visible fluorophores, which can also be observed in 3D using confocal fluorescence microscopy.

Infrared spectroscopy involves weaker energies by probing only vibrational levels. Both radiation-induced damages and Rayleigh scattering (proportional to 1/l 4 ) are weaker than in the UV-visible range. Since infrared wavelength absorption is specific for a given chemical bond, it allows chemical mapping of endogenous 7,8 (amide, phosphate) and exogenous compounds such as metal-carbonyl derivatives. [9][10][11][12] Interestingly, metalcarbonyl units have also been used in fluorescent cellimaging. 2,5,[13][14][15][16] However, to our knowledge, multimodal detection involving both luminescence and infrared vibrational spectro-and microscopies has not been performed yet.

We show here that correlative studies can be efficiently carried out with multimodality arising from a unique molecular core-Single Core Multimodal Probe for Imaging, SCoMPInamely, a single rhenium tris-carbonyl moiety (1, see Scheme 1) that has been designed to display infrared and luminescent properties, easily recognizable from endogenous cell response. This imaging approach indicates that 1 localizes to the Golgi apparatus of MDA-MB-231 cells.

Metal tris-carbonyl moieties (including Mn, Re, Os) have been used as IR-labels 17 in few cases of subcellular mapping (IR or Raman). 9-12 C 3v local symmetry of M(CO) 3 complexes induces two bands of absorption in the IR-transparency window of the cell: E-band (asymmetric stretching, doubly degenerate) at about 1920 cm À1 and A 1 -band (symmetric stretching) at about 2020 cm À1 . 18 These strong carbonyl absorptions previously allowed the mapping inside MDA-MB-231 breast cancer cells of an organometallic rhenium tris-carbonyl complex analogous to tamoxifen. 11,19 To correlate IR chemical mappings with fluorescence microscopy, a mixed organometallic and coordination complex was designed as follows: the IR fragment was kept, as it was shown to be a reliable probe in biological media, 11 sphere of rhenium. 20,21 In similar complexes presenting low p* orbitals on ligands, radiative metal-to-ligand charge transfer (MLCT) states are attainable upon excitation in the UV (about 330 nm) region and emit at around 520 nm. 22 A lipophilic long alkyl side chain was introduced to encourage cellular uptake. 23 Azide terminal function was added in order to compare infrared signals from N 3 and CO groups. Compound [ReCl(CO) 3 -pyta-C 12 N 3 ] 1 was synthesized as depicted in Scheme 1, using a ''click-to-chelate'' strategy. 24 Its distribution in MDA-MB-231 breast cancer cells (incubation for 1 h at 37 1C in the 10-micromolar range; see ESIw) was studied using a bimodal approach: IR and luminescence imaging was performed, pointing out its localization to the Golgi apparatus.

IR spectra were recorded in the 1850-2200 cm À1 range corresponding to the IR-transparency window of a typical eukaryotic cell. 17 The FTIR spectrum of compound 1 (solid form, Fig. 1A-b) shows both E and A 1 -bands characteristic of the Re(CO) 3 moiety, at 1920 and 2025 cm À1 , respectively, and a weak absorption at 2096 cm À1 corresponding to the azide moiety. UV absorption bands at 300 nm have been assigned to intraligand p-p* transitions while the broad 320-350 nm absorption band is attributed to the MLCT transition (Fig. S1, ESIw). 20,21 Irradiation in this band triggers a large radiative emission band at ca. 510 nm, characterized by a quantum yield of 0.19% in a water : ethanol (1 : 1) mixture at room temperature (Fig. 1B-c and Table S1, ESIw).

MDA-MB-231 cells were grown on slides (see ESIw), and incubated with 1 in the 10-micromolar range for 1 h. They were observed in wide field fluorescence microscopy: images and intensity profiles pointed out perinuclear location of 1 (Fig. 2 Single cells were mapped using SR-FTIR-SM in mid-IR. Maxima of absorption (or hot spots, see ESIw) for several IR-bands are displayed in Fig. 3. Hot spots of E and A 1 -bands of 1 correspond to each other (Fig. 3c andd: E in red and A 1 in cyan respectively, and Fig. 3g: overlay in white), showing that it is possible to detect 1 in a single cell using either the E or A 1 -band.

Moreover, the radiative emission signal of 1 on the same cell (green area in Fig. 3e) matched the E and A 1 -hot spots. These results provide evidence for the integrity of the bimodal core of 1 in an intracellular environment and the reliability of the bimodal IR and luminescence imaging.

Phosphate (asymmetric stretching, 1240 cm À1 , Fig. 3b, green) and amide (not shown) hot spots are colocalized and partly overlaid (Fig. 3f, yellow) with the E-band (red). As phosphate and amide hot spots are nucleus IR-signature, 7 these IR-mappings also point out a spatial proximity between 1 and the nucleus. Although the resolution of SR-FTIR is diffraction limited (Abbe criteria, resolution of ca. l/2) with a pixel set to 3 Â 3 mm 2 these mappings are consistent with the fluorescence studies. Additional IR and luminescence mappings are presented in Fig. S4 (ESIw).

To confirm the attribution of the IR and fluorescent mappings to 1, spectra have been recorded for a collection of cells (FTIR) or at the single-cell level (SR-FTIR and SR-UV-SMs). The IR-signals of 1 were observed in a FTIR spectrum of cells (ca. 41 000) incubated with 1 and deposited on the nitrocellulose membrane (Fig. 1A-c). The SR-FTIR-SM spectrum (Fig. 1A-d) was recorded for a single cell at the black cross shown in Fig. 3g. Both spectra matched that of the solid compound (Fig. 1A-b). Interestingly, the weak asymmetric stretching of the azide group at 2096 cm À1 was also detected in the two cases (single cells and cell collection). None of these signals were found on control cells (Fig. 1A-a). As observed in IR spectroscopy, the fluorescence emission spectrum of cells incubated with 1 (Fig. 1B-b) matched that of the pure compound in solution (Fig. 1B-c) with interestingly weak cellular autofluorescence in the 480-540 nm range (considering the endogenous emission of control cells in Fig. 1B-a).

To investigate the perinuclear distribution of 1, its accumulation in the Golgi apparatus was queried, since Golgi bodies are located close to the nuclear envelope. 25 The Golgi apparatus is also known to be targeted by lipophilic derivatives, 26 which is the case for 1 with its organometallic core and its long side chain. In addition, a localization in the Golgi apparatus has been previously suspected for a lipophilic rhenium triscarbonyl orthophenanthroline complex coupled with biotin. 27 In Fig. 2, colocalization experiments using a Golgi tracker, the BODIPY s TR C 5 -ceramide complexed to BSA, show an overlay (yellow) between 1 (green) and this tracker (red) with similar intensity profiles across the cell. Quantitative analyses strongly suggest the colocalization of 1 with the Golgi apparatus (Fig. 2: Pearson's coefficient 0.93, overlap coefficient 0.96, intensity correlation quotient 0.41, see ESIw).

In conclusion, we report here the first successful bimodal subcellular imaging of a single core organometallic multimodal probe using both its infrared and luminescent signatures. The SCoMPI 1, whose single metal-centered core combines both modalities, displays photophysical properties allowing its univocal detection in cells. Both spectromicroscopies are consistent with one another and show a perinuclear location of 1 that was assigned to the Golgi apparatus. Other metal-CO derivatives have been found to be accumulated in specific organelles. 10,11,13,[28][29][30] These various locations show that these probes can be delivered to different cell-compartments depending on their appended moiety, which is a valuable property for imaging applications. 13 Since infrared and luminescence spectroscopies are complementary for bio-detection and bio-imaging, IR-luminescent (L)Re(CO) 3 SCoMPIs are of great potential and their multiple modalities open up wide prospects for cross-correlative studies in biological media. IR bio-imaging is emerging, with potential applications at the tissue level. The elaboration of this small molecule chemistry to target organelles or tag molecules for imaging is likely to contribute substantially to our molecular-level understanding of chemical processes in cells.

ENS, CNRS (PIR-CNRS-PCV-prise de risque, UMR8640, 7203), UPMC-Paris 6 are acknowledged for financial support and ENS for SC's PhD fellowship. We thank SOLEIL committee for beamtime (project 20100758).

Notes and references

  Scheme 1

  and Fig. S2 (ESIw), green), with the nucleus stained with DAPI (Fig. 2 and Fig. S2 (ESIw), blue). Confocal microscopy confirmed that the molecule was localized outside the nucleus: Fig. S3 (ESIw) shows a typical distribution of 1 (green) close to and underneath the nucleus (blue).

Fig. 1 (

 1 Fig. 1 (A) IR spectra in the cell transparency window: (a) FTIR spectrum of a collection of control cells deposited on a nitrocellulose membrane; (b) FTIR spectrum of solid compound 1; (c) FTIR spectrum of a collection of cells incubated with 1 (25 mM, 1 h, about 41 000 cells) and deposited on a nitrocellulose membrane; (d) SR-FTIR-SM spectrum (recorded at the black cross in Fig. 3g) on a single cell incubated with 1 (10 mM, 1 h). (B) Emission spectra (exc. 350 nm): (a) of a MDA-MB-231 single control cell, (b) of a MDA-MB-231 single cell incubated with 1 (10 mM, 1 h), (c) of a 6.0 Â 10 À5 M solution of 1 in water : ethanol 1 : 1. Spectra (a) and (b) recorded at the DISCO beamline (see ESIw).

Fig. 2

 2 Fig. 2 MDA-MB-231 cell incubated with 1 (25 mM, 1 h) and the tracker. Bright field image (scale bar 10 mm) superimposed to epifluorescence images: (a) merge of 1 (green) and DAPI (blue); (b) merge of the Golgi tracker (red) and DAPI (blue); (c) merge of 1 (green) and the Golgi tracker (red) with their overlay in yellow and DAPI (blue). Intensity profiles along the arrow on (c) image: 1 (green trace), Golgi tracker (red trace), DAPI (blue trace).

Fig. 3

 3 Fig. 3 MDA-MB-231 cell incubated with 1 (10 mM, 1 h). (a) Bright field image (scale bar 10 mm). (b-d) SR-FTIR mappings, hot spots (see ESIw) (pixel size: 3 Â 3 mm 2 ): (b) phosphate asymmetric stretching (green), (c) E-band (red), (d) A 1 -band (cyan). (e) Epifluorescence image, localization of 1 (green). (f-g) Overlays of SR-FTIR hot spots: (f) overlay (yellow) of b (green) and c (red), (g) overlay (white) of c (red) and d (cyan). The black cross on (g) locates the d trace in Fig. 1A.


S Cosh
email: scosh@une.edu.au

Carriere

The association of vision loss and dimensions of depression over 12 years in older adults: findings from the Three City Study

Keywords: Vision impairment, visual loss, depression symptoms, ageing, mental wellbeing, mental health

Background: The established relationship between vision impairment and depression is limited by the examination of depression only as a unidimensional construct. The present study explores the vision-depression relationship using a dimensional approach.

Methods: 9036 participants aged 65 years and above enrolled in the Three-City study were included. Relationships between baseline near Vision Impairment (VI) or self-reported distance Visual Function (VF) loss with trajectory of four dimensions of depressiondepressed affect, positive affect, somatic symptoms and interpersonal problems -over 12 years were examined using mixed-effects models. Depression dimensions were determined using the four-factor structure of the Centre for Epidemiology Studies-Depression Scale (CESD).

Results: In the fully adjustment models, mild near VI predicted poorer depressed affect (b= 0.04, p = .002) and positive affect (b = -0.06, p <.001) over time, with evidence of longer term adjustment. Distance VF loss was associated with poorer depressed affect (b = 0.27, p = <.001), positive affect (b = -0.15, p = .002), and somatic symptoms (b = 0.18, p = <.001) at baseline, although only the association with depressed affect was significant longitudinally (b = 0.01, p = .001). Neither near VI nor distance VF loss were associated with interpersonal problems.

Limitations: This paper uses a well-supported model of depression dimensions, however, there remains no definite depression dimension model. Distance VF loss was self-reported, which can be influenced by depression symptoms.

Conclusions: Vision impairment in older adults is primarily associated with affective dimensions of depression. A reduction in social connectedness and ability to engage in pleasurable activities may underlie the depression-vision relationship. Older adults with vision loss may benefit from targeted treatment of affective symptoms, and pleasant event scheduling.

Vision impairment (VI) is common in older adults, with an estimated prevalence of 25% in those aged over 70 [START_REF] Stevens | Global prevalence of vision impairment and blindness: magnitude and temporal trends, 1990-2010[END_REF]; and VI substantially contributes to burden of disease in Europe [START_REF] Mathers | Projections of global mortality and burden of disease from 2002 to 2030[END_REF]). An association between VI and depression in the elderly population is well established [START_REF] Carriere | A prospective study of the bi-directional association between vision loss and depression in the elderly[END_REF][START_REF] Court | Visual impairment is associated with physical and mental comorbidities in older adults: a cross-sectional study[END_REF][START_REF] Hong | Visual impairment and depressive symptoms in an older Australian cohort: longitudinal findings from the Blue Mountains Eye Study[END_REF], with prevalence of comorbid depression in older adults with VI estimated to be around 30% [START_REF] Hayman | Depression in Older People: Visual Impairment and Subjective Ratings of Health[END_REF][START_REF] Hong | Visual impairment and depressive symptoms in an older Australian cohort: longitudinal findings from the Blue Mountains Eye Study[END_REF]. Comorbid depression leads to marked reductions in quality of life, increased disability, and increased mortality risk [START_REF] Eisele | Determinants of health-related quality of life in older primary care patients: results of the longitudinal observational AgeCoDe Study[END_REF][START_REF] Hernandez Trillo | The impact of visual and nonvisual factors on quality of life and adaptation in adults with visual impairment[END_REF][START_REF] Zheng | Increased mortality risk among the visually impaired: the roles of mental well-being and preventive care practices[END_REF], underscoring the need to better understand the relationship between VI and depression and the long-term trajectory of depression symptoms in VI.

To date, when examining the association with VI, depression has been examined as a single disorder-based category; a methodology with substantial limitations. Major depressive disorder (MDD) is a polythetic disorder, characterized by a number of combinations of different symptoms [START_REF] Vrieze | Dimensions in major depressive disorder and their relevance for treatment outcome[END_REF]. A unidimensional approach to depression fails to capture the substantial heterogeneity seen between individuals with depression [START_REF] Basso | Neuropsychological correlates of symptom dimensions in inpatients with major depressive disorder[END_REF][START_REF] Watson | Differentiating the mood and anxiety disorders: a quadripartite model[END_REF]. Emerging evidence highlights the utility of a dimensional approach, which explores symptom dimensions rather than dichotomizing depression. Divergent prognoses, treatment needs, and quality of life outcomes have been reported for varying depression dimensions [START_REF] Shafer | Meta-analysis of the factor structures of four depression questionnaires: Beck, CES-D, Hamilton, and Zung[END_REF][START_REF] Soskin | Antidepressant effects on emotional temperament: toward a biobehavioral research paradigm for major depressive disorder[END_REF][START_REF] Uher | Depression symptom dimensions as predictors of antidepressant treatment outcome: replicable evidence for interest-activity symptoms[END_REF][START_REF] Wardenaar | Symptom-specific course trajectories and their determinants in primary care patients with Major Depressive Disorder: Evidence for two etiologically distinct prototypes[END_REF]. Moreover, different depression dimensions have been shown to differentially correlate with other mental and physical conditions [START_REF] Watson | Differentiating the mood and anxiety disorders: a quadripartite model[END_REF] and may have different neurobiological substrates [START_REF] Basso | Neuropsychological correlates of symptom dimensions in inpatients with major depressive disorder[END_REF]. Thus analyses using disorder-based categories may result in a substantial loss of valuable information [START_REF] Brown | A proposal for a dimensional classification system based on the shared features of the DSM-IV anxiety and mood disorders: implications for assessment and treatment[END_REF]. By contrast, a dimensional approach is better suited to understanding the pathogenesis and course of psychiatric disorders and meeting the mental health needs of the elderly population [START_REF] Bryant | Anxiety disorders in older adults: looking to DSM5 and beyond[END_REF][START_REF] Prisciandaro | A comparison of the predictive abilities of dimensional and categorical models of unipolar depression in the National Comorbidity Survey[END_REF].

Currently a dimensional approach to depression has not been applied in VI research, limiting understanding of the VI-depression association and the related needs of older adults with VI. This study therefore aims to examine the longitudinal relationship between near VI and distance Visual Function (VF) loss in older adults with depression dimension symptoms over 12 years.

Method

This study forms part of the SENSE-Cog multi-phase research programme, funded by European Union Horizon 2020 programme. SENSE-Cog aims to promote mental well-being in older adults with sensory and cognitive impairments (www.sense-cog.eu/). The first work package of this project aims to better understand the links between sensory, cognitive and mental ill-health in older Europeans.

Sample

Participants were recruited as part of the multi-centre Three-City (3C) study (The 3C Study Group, 2003), a prospective cohort study of community-dwelling French adults aged 65 years and over. A total of 9294 participants were recruited from electoral rolls in three cities (Bordeaux, Dijon and Montpellier) between 1999 and 2001. A standardized evaluation including a face-to-face interview and clinical examinations were undertaken at baseline. Participants were followed up at 2-3 year intervals for up to 12 years. The study protocol was approved by the Ethics Committees of the University-Hospitals and written informed consent was obtained from each participant.

Depression Measures

Depression symptoms were examined using the 20-item Centre for Epidemiology Studies-Depression scale (CESD) [START_REF] Radloff | The CESD Scale: A self-report depression scale for research in the general population[END_REF]. A four-factor structure proposed by Radloff is most commonly replicated [START_REF] Radloff | The CESD Scale: A self-report depression scale for research in the general population[END_REF][START_REF] Shafer | Meta-analysis of the factor structures of four depression questionnaires: Beck, CES-D, Hamilton, and Zung[END_REF]. The four factors reflect different dimensions of depression symptoms: depressed affect (DA) assessed by 7 items (felt sad, crying spells, could not shake the blues, depressed, lonely, fearful, felt as though life is a failure); positive affect (PA) assessed by 4 items (hope about the future, enjoyed life, felt as good as others, felt happy); somatic symptoms (S) as represented by 7 items (poor appetite, restless sleep, could not get going, concentration difficulties, everything an effort, bothered by things, talked less than usual); and 2 items that examine interpersonal problems (IP; people dislike me, people were unfriendly). The four dimensions are reported to be phenomenologically and psychometrically distinct [START_REF] Devins | Measuring depressive symptoms in illness populations: Psychometric properties of the Center for Epidemiologic Studies Depression (CES-D) scale[END_REF][START_REF] Leventhal | Dimensions of depressive symptoms and smoking cessation[END_REF][START_REF] Shafer | Meta-analysis of the factor structures of four depression questionnaires: Beck, CES-D, Hamilton, and Zung[END_REF].The four-factor structure of the CESD has been validated across a number of populations [START_REF] Shafer | Meta-analysis of the factor structures of four depression questionnaires: Beck, CES-D, Hamilton, and Zung[END_REF] including community dwelling older adults [START_REF] Gellis | Assessment of a brief CES-D measure for depression in homebound medically ill older adults[END_REF] and has also been validated in the French version of the CESD in a population of community dwelling French adults [START_REF] Morin | Psychometric properties of the Center for Epidemiologic Studies Depression Scale (CES-D) in French clinical and nonclinical adults[END_REF]. The scores for each item were summed for the different dimensions. For PA, items were not reverse scored as is required for calculating total CESD scores, thus lower scores indicate more severe depression. For the other dimensions, higher scores are indicative of more severe depression symptomatology.

Vision measures

Binocular near visual acuity was assessed using the Parinaud scale (a Jaeger-like reading test commonly used in France) at all time points. Assessment was undertaken using presenting vision with usual optical correction where applicable. Identical cards were used at each centre with a standardised reading distance of 33 cm. Mild VI was classified as Parinaud 3 or 4 (Snellen equivalent 20/30-20/60) and moderate to severe VI as Parinaud > 4 (Snellen equivalent < 20/60). Distance visual function was assessed in the face-to-face interview. Distance VF loss was classified as self-reported inability or difficulty in recognising a familiar face at 4 metres.

Socio-demographic and health variables

Socio-demographic and health-related information was collected during the standardised interview at baseline. Known covariates of depression and/or vision were assessed, including variables such as education level (elementary schooling, secondary school, higher education), monthly income (low <€760, €760-2280, >€2280, withheld/missing), and marital status. Alcohol consumption (<10 grams, 10-40 grams, >40 grams per day), tobacco use (current-, past -, or nonsmoker) and falls during the past 12 months were also assessed. A composite score representing activity limitations was calculated based on scores from the Rosow-Breslau scale, the Lawton-Brody Instrumental Activities of Daily Living (IADL) scale and the Katz Index of Independence in Activities of Daily Living; activity limitations were (categorised as autonomous; dependent for mobility; mobility and IADL limitations; and dependent in 3 or more areas of functioning; [START_REF] Barberger-Gateau | A hierarchical model of domains of disablement in the elderly: a longitudinal approach[END_REF]. During the detailed medical questionnaire history of myocardial infarction and use of psychotropic medication (ATC classification codes: N05A-C, N06A-B) in the past month was obtained. A medical examination assessed diabetes (fasting glycemia≥7mmol/L and/or anti-diabetic treatment), and blood pressure was measured using a digital electronic tensiometer OMRON M4. Hypertension was defined using the 140/90 mmHg threshold or treatment with bloodpressure lowering drugs. Cognitive functioning was also assessed using the Mini Mental State Examination (MMSE; <16, 16-23 or ≥24).

Statistical Analysis

The relationship between baseline near VI and distance VF loss at baseline with the trajectory of depression dimension symptoms over 12 years were assessed using multilevel growth models. Due to few participants reporting any IP symptomatology, the distribution of IP problems was not amenable to linear models, thus only S, DA and PA dimensions were examined using multilevel models (IP was examined using logistic mixed models). Due to non-normal distribution, dimension scores for PA, DA and S were transformed using the estimated link function [START_REF] Proust-Lima | How to use LCMM package for normalizing psychometric tests[END_REF]. Scores were then converted to z-scores for subsequent analyses.

A series of exploratory models [START_REF] Singer | Applied Longitudinal Data Analysis: Modeling Change and Event Occurrence[END_REF] were undertaken separately for each depression dimension (PA, DA, S) to assess the longitudinal effects of vision on depression symptoms over time; with all vision-related variables entered in a single model, thus models adjusted for the effect of VI on VF loss and VF loss on VI. In an initial step, an unconditional growth model adjusted only for time was undertaken to examine if depression dimension symptoms changed significantly over time. Secondly, time and its quadratic trend were entered to establish the trajectory of depression symptomatology. Exploratory analyses indicated that, for each dimension, depression trajectory was curvilinear and the model with a quadratic trend was the best fit of the data. These models then served as the basis for comparison for the subsequent models exploring the association between VI and VF loss with symptom dimensions. In a third step, baseline mild VI, moderate to severe VI, VF loss, and their interactions with time were entered concurrently into the model. A range of variables such as functional ability, age, gender, education level, income and physical health have been identified as related to depression amongst older adults (see e.g. [START_REF] Blazer | Depression in Late Life: Review and Commentary[END_REF][START_REF] Pennix | Exploring the effect of depression on physical disability: longitudinal evidence from the established populations for epidemiologic studies of the elderly[END_REF]. Thus, in the final stage, three models were carried out for each dimension which adjusted for such known covariates that have been previously documented in the literature. The first adjusted for age, sex and study centre; the second model additionally adjusted for education level, income, marital status, and use of psychotropic medication; and the third model additionally adjusted for cognitive function (MMSE), activity limitations, falls in past 12 months, hypertension, diabetes, smoking status, alcohol consumption, and history of myocardial infarction, with covariates added as additional explanatory variables in the models.

The IP score was converted to a binary variable: presence of any IP symptomology and absence thereof. A logistic mixed model [START_REF] Carriere | Choosing marginal or random-effects models for longitudinal binary responses: application to self-reported disability among older persons[END_REF] was used to explore if those with baseline VI or VF loss had differential odds of experiencing IP symptoms over the twelve years of follow-up. Logistic mixed models take into account within-subject correlation and model the individual time evolutions of the outcome across the 12 years of follow-up; thus logistic mixed models also allow for the reversibility of symptoms. Three separate models were conducted for IP, adjusting for the same covariates as the multilevel models. Interactions between vision with sex, education and income were also systematically examined in all analyses. Analyses were conducted using SAS 9.4 (SAS Institute, Inc., Cary, NC).

Results

Of the 9294 participants recruited, 246 were missing baseline CESD or vision data and a further 12 had not completed the CESD due to impaired cognitive function as assessed by the trained interviewer. Thus a total of 9036 participants with complete depression and vision data at baseline were included in analyses. Participants had a mean age of 74.3 (SD=5.58) at baseline. The majority were female (60.7%, n = 5543). At baseline, prevalence of mild VI was 9.0% (n = 810), moderate to severe VI was 4.3% (n = 386) and distance VF loss was 5.4% (n = 491). Those with poor vision were older, less educated, less likely to be married, had greater functional impairment and were in poorer physical health on all assessed health outcomes than those without baseline impairment (Table 1).

Depressed Affect

As shown in Table 2, in the fully adjusted model (model 3), mild VI was not associated with DA at baseline (b = -0.018, SE = 0.035, p = .60). However, mild VI was associated with an initial increase in DA symptomatology over time (b = 0.040 for linear interaction with time, SE = 0.013, p = .002), with symptoms then beginning to plateau (b = -0.003 for quadratic interaction with time, SE = 0.001, p = .01). Moderate to severe VI was also not related to DA at baseline. However, moderate to severe VI was associated with increasing DA symptoms over time (b = 0.043 linear interaction with time, SE = 0.021, p = .04). Distance VF loss was associated with increased DA symptoms at baseline (b = 0.265, SE = 0.048, p = <.001). In those with distance VF loss an initial small improvement in DA was seen before a longer term increase in DA symptoms (b = 0.005 for quadratic interaction with time, SE = 0.002, p = .001).

Positive Affect

Mild VI was associated with better PA at baseline (b = 0.107, SE = 0.04, p .003; Table 3). Mild VI was, however, associated with worsening PA symptoms over time (b = -0.060 for linear interaction with time, SE = 0.014, p <.001), before a tapering of symptoms over the longer term (b = 0.003 for quadratic interaction with time, SE = 0.001, p = .02). Moderate to severe VI was not associated with PA symptoms. Distance VF loss, on the other hand, was related to poorer PA at baseline (b = -0.147, SE = 0.047, p = .002), but had no longitudinal relationship with PA.

Somatic Symptoms

Neither mild nor moderate to severe VI were associated with somatic symptoms in the fully adjusted models, although a longitudinal relationship with moderate to severe VI was close to significance (Table 4). Distance VF loss was associated with greater somatic symptoms at baseline (b = 0.175, SE = 0.046, p = <.001); however, this was not significant longitudinally (b = -0.007, SE = 0.020, p = .72).

Interpersonal Problems

Neither mild nor distance VF loss were associated with a greater likelihood of experiencing IP problems over 12 years in the fully adjusted models (OR = 0.84 95% CIs 0.64-1.11, p =.22, OR = 1.07 95% CIs 0.76-1.51, p =.69, respectively; Table 5). In the partially adjusted models, moderate to severe VI was associated with interpersonal problems, although this was just outside of significance in the fully adjusted model (OR = 1.42, 95% CIs 0.99-2.03, p =.06). In all models, none of the tested interactions were significant.

Discussion

This study adopted a novel dimensional approach to extend past research which has previously established cross-sectional [START_REF] Court | Visual impairment is associated with physical and mental comorbidities in older adults: a cross-sectional study[END_REF][START_REF] Garin | Visual impairment and multimorbidity in a representative sample of the Spanish population[END_REF][START_REF] Hayman | Depression in Older People: Visual Impairment and Subjective Ratings of Health[END_REF] and longitudinal [START_REF] Carriere | A prospective study of the bi-directional association between vision loss and depression in the elderly[END_REF][START_REF] Hong | Visual impairment and depressive symptoms in an older Australian cohort: longitudinal findings from the Blue Mountains Eye Study[END_REF] relationships between VI and depression. Vision had differential relationships with different dimensions of depression. Affective dimensions, specifically depressed affect and positive affect, were more closely tied to VI and VF loss than somatic or interpersonal symptoms. Thus the present findings provide a more comprehensive picture of depression in vision and the dimensions that underlie the vision-depression relationship in the elderly population with VI.

Our findings demonstrated the varied relationships between different types of VI and depression dimensions. Distance VF loss was associated cross-sectionally with DA, PA and somatic dimensions, whereas near VI did not have any cross-sectional associations with worse depressive symptomatology. This finding may indicate that distance VF loss is associated with greater initial distress that may remit over time, at least for PA and somatic dimensions. Alternatively, those who were more depressed at baseline may have been more likely to self-report vision problems. Notably in distance VF loss there was no evidence of adjustment to DA, suggesting that some dimensions may persist even in the absence of meeting a threshold for a single disorder-based assessment of depression. While the absence of cross-sectional associations between near VI and depression symptoms was perhaps unexpected, this finding might also reflect that depression likely increases with worsening severity of the loss, and hence may be more strongly associated to depression symptoms over time.

The perhaps surprising finding that mild VI was associated with better PA at baseline might be explained through health behaviours. Previously higher PA has been associated with lack of adherence to treatment, and inaccurate diagnosis and healthcare due to the underreporting of symptoms [START_REF] Pressman | Does positive affect influence health?[END_REF]. One possibility then is that those with higher PA might be more likely to use inappropriate optical correction thus resulting in higher rates of VI as assessed via presenting correction. Correctible VI due to use of the wrong optical correction common in older adults [START_REF] Taylor | Costs of Interventions for Visual Impairment[END_REF]. In the present study mild VI was, however, associated with a worsening of depression symptoms over time for both PA and DA. Yet for both dimensions there was a small longer term improvement in symptoms, indicative of adjustment, which is consistent with reports that older adults with VI exhibit depression symptoms at 5 but not 10 years post-onset [START_REF] Hong | Visual impairment and depressive symptoms in an older Australian cohort: longitudinal findings from the Blue Mountains Eye Study[END_REF]. Our findings do suggest, however, that adjustment might be more complex than previously reported, with differential adjustment observed for different dimensions and types of VI.

Although a range of factors that likely facilitate adjustment in VI have been reported [START_REF] Senra | Psychologic adjustment to irreversible vision loss in adults: a systematic review[END_REF], ongoing research is needed to better understand facilitators of adjustment for each dimension in order to help promote and improve quality of life [START_REF] Wang | Psychosocial adaptation status and health-related quality of life among older Chinese adults with visual disorders[END_REF].

Notably, within the present study, moderate to severe VI was only associated with DA over time, but was unrelated to the other depression dimensions. Due to a smaller sample meeting the moderate to severe threshold, the study may have been underpowered to detect such relationships.

However, moderate to severe VI was associated with IP in the partially adjusted models, yet this was no longer significant after full adjustment for physical health covariates. Given that VI is associated with poorer physical health [START_REF] Lam | Reported visual impairment and risk of suicide: the 1986-1996 national health interview surveys[END_REF] and greater functional limitations [START_REF] Bookwala | Poor vision, functioning, and depressive symptoms: a test of the activity restriction model[END_REF]Daien et al., 2011Daien et al., , 2014;;Peres et al., 2017), it is possible that adjustment for these other factors might have attenuated the depression associations observed in the unadjusted models. Moreover, adjustment was noted in some dimensions in mild VI, thus those with moderate to severe VI might have already adjusted to their impairment. Relatedly, fear of total vision loss and future deterioration of vision are a central cause of distress in VI [START_REF] Wang | Psychosocial adaptation status and health-related quality of life among older Chinese adults with visual disorders[END_REF]), yet may be less pertinent in those with already more severe VI.

The present results also shed further light on prior depression and vision research. Variations in the prevalence of comorbid depression in VI and eye diseases have been reported previously.

Notably, one study using the Goldberg Depression Scale, which has a high proportion of items that assess somatic symptoms, reported relatively low rates of comorbid depression ranging from 4.3% in glaucoma to 10.5% in Age-related Macular Degeneration (AMD) [START_REF] Eramudugolla | Co-morbidity of depression and anxiety in common age-related eye diseases: a population-based study of 662 adults[END_REF]. Other studies which have utilised the Hospital Anxiety and Depression Scale and Geriatric Depression Scale, both of which largely focus on affective symptoms of depression, have reported depression prevalence between 22-35% in VI and eye diseases [START_REF] Hayman | Depression in Older People: Visual Impairment and Subjective Ratings of Health[END_REF][START_REF] Popescu | Explaining the relationship between three eye diseases and depressive symptoms in older adults[END_REF][START_REF] Van Der Aa | Major depressive and anxiety disorders in visually impaired older adults[END_REF][START_REF] Yokoi | Predictive factors for comorbid psychiatric disorders and their impact on vision-related quality of life in patients with high myopia[END_REF]. Thus the variation in prevalence rates may reflect the varied relationships between vision and depression dimensions. In addition, this study builds on previous depression dimension work that has shown prospective associations between affective depression dimensions with a number of physical health outcomes [START_REF] Basso | Neuropsychological correlates of symptom dimensions in inpatients with major depressive disorder[END_REF][START_REF] Steptoe | Positive affect and psychobiological processes relevant to health[END_REF]. Our findings suggest that DA and PA are also related to aspects of vision and, moreover, that associations between affective dimensions and health might be bidirectional, with our results indicating that poor vision predicted poorer DA and PA over time.

The results also shed further light on the range of possible mechanisms that might underlie the vision-depression association. Avoidance of social situations is observed in poor vision, leading to social isolation and reduced social support [START_REF] Bookwala | Poor vision, functioning, and depressive symptoms: a test of the activity restriction model[END_REF][START_REF] Hayman | Depression in Older People: Visual Impairment and Subjective Ratings of Health[END_REF]; both of which predict depression onset [START_REF] Penninx | Exploring the effect of depression on physical disability: longitudinal evidence from the established populations for epidemiologic studies of the elderly[END_REF]. Notably, positive affect is related to social connectedness and support [START_REF] Brown | A proposal for a dimensional classification system based on the shared features of the DSM-IV anxiety and mood disorders: implications for assessment and treatment[END_REF][START_REF] Steptoe | Positive affect and psychobiological processes relevant to health[END_REF] and, concomitantly, those with depressed affect have fewer social connections [START_REF] Steptoe | Positive affect and psychobiological processes relevant to health[END_REF] and report greater levels of loneliness [START_REF] Wardenaar | Symptom-specific course trajectories and their determinants in primary care patients with Major Depressive Disorder: Evidence for two etiologically distinct prototypes[END_REF]. Accordingly, the association between VI and affective symptoms suggests that social isolation and loss of social networks may be crucial factors underlying the association between VI and depression. Similarly, reduced functional independence observed in VI has been proposed as a mechanism [START_REF] Carriere | A prospective study of the bi-directional association between vision loss and depression in the elderly[END_REF][START_REF] Chou | Combined effect of vision and hearing impairment on depression in older adults: evidence from the English Longitudinal Study of Ageing[END_REF][START_REF] Evans | Depression and anxiety in visually impaired older people[END_REF]. Limited functional ability may also limit or restrict the ability to undertake pleasurable activities and events, resulting in reduced PA [START_REF] Wahl | Robustness of personality and affect relations under chronic conditions: the case of age-related vision and hearing impairment[END_REF].

Likewise reduced ability to engage in hobbies such as reading might further underlie the visiondepression association via reduced PA. Conversely, it has been argued that for those with increased somatic symptoms of depression, common biological or ageing pathways likely underlie both the physical ill-health and depressive episode [START_REF] Anderson | Biological phenotypes underpin the physiosomatic symptoms of somatization, depression, and chronic fatigue syndrome[END_REF]. The lack of associations between VI and somatic symptoms suggests that, at least in this sample, shared biological processes were less likely to be the mechanism underlying depression in VI.

Given that interventions targeted to specific dimensions can improve efficacy of depression treatment [START_REF] Soskin | Antidepressant effects on emotional temperament: toward a biobehavioral research paradigm for major depressive disorder[END_REF], our findings indicate that a focus on treating affective symptoms is better suited to older adults with VI. This is particularly pertinent given that DA and symptoms of PA predict greater depression severity and poorer treatment response [START_REF] Uher | Depression symptom dimensions as predictors of antidepressant treatment outcome: replicable evidence for interest-activity symptoms[END_REF][START_REF] Vrieze | Dimensions in major depressive disorder and their relevance for treatment outcome[END_REF]. Behavioural activation and pleasant event scheduling are beneficial therapeutic components for treating affective symptoms [START_REF] Treadway | Reconsidering anhedonia in depression: lessons from translational neuroscience[END_REF] and behavioural activation is superior to supportive therapy for preventing depression in AMD [START_REF] Rovner | Low vision depression prevention trial in age-related macular degeneration: a randomized clinical trial[END_REF]. Given limitations in mobility and ability to engage in social outings and activities such as reading, a focus on generating and identifying alternate activities which generate PA may also be integral to improving wellbeing [START_REF] Wahl | Robustness of personality and affect relations under chronic conditions: the case of age-related vision and hearing impairment[END_REF]. The results also highlighted some variation in treatment needs depending on type of VI.

Mild VI was slower to remit, thus promoting adjustment may be of particular benefit in this population. Furthermore, DA did not remit in those with distance VF loss and given the bi-directional relationship between distance VF loss and depression [START_REF] Carriere | A prospective study of the bi-directional association between vision loss and depression in the elderly[END_REF], treatment of DA symptoms may be of particular importance.

Strengths and Limitations

Study strengths include the large sample and length of follow up which allowed for the longer term trajectories of depression dimensions and adjustment to be explored, as well as the inclusion of measured binocular near visual acuity. However, this paper is presented with a number of limitations.

Firstly distance VF loss was assessed by only 1 item and, being self-reported, may have been influenced by existing depression symptoms. Moreover, although the model of depression dimensions utilized in this study has empirical support, debate remains over the best conceptualization of depression dimensions and currently there is no conclusive model (van Loo, de Jonge, Romeijn, [START_REF] Van Loo | Data-driven subtypes of major depressive disorder: a systematic review[END_REF]. It is possible that alternate dimensional models or depression measures would yield varied associations with vision. In addition, the CESD was originally designed as a general measure of depression rather than to assess specific subscales or factors [START_REF] Shafer | Meta-analysis of the factor structures of four depression questionnaires: Beck, CES-D, Hamilton, and Zung[END_REF]; ongoing research focused on assessment of depression dimensions in VI would be valuable. Relatedly, the interpersonal problems dimension was assessed by only two items and few participants endorsed any IP symptoms. Thus findings related to the IP dimension may not reflect the full range of interpersonal dysfunction in older adults with Additionally, although Quality of Life (QoL) is related to depression and VI, no QoL data were available in this study, thus any possible confounds of QoL could not be ascertained. Future research might further consider the interplay of QoL in the relationship between specific depression dimensions and vision. A small proportion of participants had lower levels of cognitive function (as determined by the MMSE). Although these participants only completed selfreport measures when deemed capable by the trained interviewer, the extent to which underlying cognitive fucntion might have impacted self-report cannot be fully ascertained. Furthermore, specific eye diseases or conditions underlying VI were not assessed. As a result, our findings do not account for possible reversibility of VI (e.g. due to cataract surgery).

Conclusions

The dimensional approach used here allows for increased understanding of the mental health needs of the elderly population with VI. Older adults with poor vision predominantly experienced a worsening of affective symptoms. Although longitudinal associations were observed with dimensions of depression, older adults with near VI showed some evidence of adjustment over time. Findings suggest that VI might be related to depression via a reduction in social connectedness and ability to engage in pleasurable activities. Older adults with VI may particularly benefit from targeted treatment of affective symptoms to enhance wellbeing.

Table 1 : Baseline characteristics of the study population by vision loss. Three-City (3C) Study 1999-2001, N=9036.

 1

	No visual loss	Mild VI only	Moderate to	VF loss only	VI and VF loss	p
	n= 7552	n= 726	Severe VI only	n= 288	n= 203
			n= 267

Table 2 : Association between baseline Vision Loss and Depressed Affect (z-score). Three-City (3C) Study

 2

		Model 1			Model 2			Model 3
	b	SE	p	b	SE	p	b	SE	P

Table 3 : Association between baseline Vision Loss and Positive Affect (z-score). Three-City (3C) Study

 3 ; sex, age, centre, education, income, marital status, psychotropic medication use Model 3: n= 8183; sex, age, centre, education, income, marital status, psychotropic medication use, MMSE, functional ability, falls, hypertension, diabetes, smoking, alcohol consumption, and history myocardial infarction

		Model 1			Model 2			Model 3
	b	SE	p	b	SE	p	b	SE	p

Table 4 : Association between baseline Vision Loss and Somatic Symptoms (z-score). Three-City (3C) Study

 4 ; sex, age, centre, education, income, marital status, psychotropic medication use Model 3: n= 8199; sex, age, centre, education, income, marital status, psychotropic medication use, MMSE, functional ability, falls, hypertension, diabetes, smoking, alcohol consumption, and history of myocardial infarction

		Model 1			Model 2			Model 3
	b	SE	p	b	SE	p	b	SE	p

Table 5 : Association between baseline Vision Loss and interpersonal problems. Three-City (3C) Study

 5 ; sex, age, centre, education, income, marital status, psychotropic medication use Model 3: n= 7103; sex, age, centre, education, income, marital status, psychotropic medication use, MMSE, functional ability, falls, hypertension, diabetes, smoking, alcohol consumption, and history of myocardial infarction

	OR	95% CI	p


Keywords: Hearing impairment, healthy ageing, mental wellbeing, sensory loss



The relationship between hearing loss and depression in older adults is unclear and longitudinal examinations are rare  Older adults with self-reported HL were more likely to have depression symptoms and a diagnosis of depression  Over 12 years, mild and severe HL were associated with onset of depression symptoms, but no incident depression diagnosis

Introduction

Hearing losses (HL) are common among older adults, with up to one third aged over 65 experiencing HL (WHO, 2012). HL substantially contributes to burden of disease [START_REF] Mathers | Projections of global mortality and burden of disease from 2002 to 2030[END_REF]Loncar, 2006, Wittchen et al., 2011) by increasing disability [START_REF] Armstrong | Depression and health-related quality of life among persons with sensory disabilities in a health professional shortage area[END_REF]. Poorer quality of life [START_REF] Chia | Hearing impairment and health-related quality of life: the Blue Mountains Hearing Study[END_REF][START_REF] Eisele | Determinants of health-related quality of life in older primary care patients: results of the longitudinal observational AgeCoDe Study[END_REF] and mental health has also been reported amongst those with HL (Armstrong et al., 2016, Heine and[START_REF] Heine | Mental health and dual sensory loss in older adults: a systematic review[END_REF]. Older adults with HL experience less emotional vitality (i.e. less personal mastery and more psychological symptoms) [START_REF] Contrera | Association of Hearing Impairment and Emotional Vitality in Older Adults[END_REF], and increased anxiety symptoms [START_REF] Contrera | Association of Hearing Impairment and Anxiety in Older Adults[END_REF][START_REF] Cosh | The association amongst visual, hearing, and dual sensory loss with depression and anxiety over 6 years: The Tromso Study[END_REF].

Concomitantly older adults with HL also report lower levels of happiness and selfefficacy than those without HL [START_REF] Contrera | Association of Hearing Impairment and Emotional Vitality in Older Adults[END_REF][START_REF] Kramer | The Association of Hearing Impairment and Chronic Diseases With Psychosocial Health Status in Older Age[END_REF].

Given that HL has been shown to significantly impinge upon the mental wellbeing of older adults, the extent to which HL might be related to depression has also been examined. Limited evidence to date indicates a cross-sectional relationship between HL and depression amongst older adults [START_REF] Gopinath | Depressive symptoms in older adults with hearing impairments: the Blue Mountains Study[END_REF][START_REF] Lee | Hearing impairment and depressive symptoms in an older chinese population[END_REF], and adults of all ages [START_REF] Ciesla | Health-related quality of life and mental distress in patients with partial deafness: preliminary findings[END_REF][START_REF] Li | Hearing impairment associated with depression in US adults, National Health and Nutrition Examination Survey 2005-2010[END_REF]. Notably reductions in activities of daily living [START_REF] Gopinath | Severity of age-related hearing loss is associated with impaired activities of daily living[END_REF], as well as self-efficacy and social network [START_REF] Mener | Hearing loss and depression in older adults[END_REF] often observed in HL, alongside increased loneliness [START_REF] Pronk | Hearing status in older persons: a significant determinant of depression and loneliness? Results from the longitudinal aging study amsterdam[END_REF], are possible mechanisms underlying the observed relationships.

However, findings regarding the relationship between HL and depression remain equivocal [START_REF] Mener | Hearing loss and depression in older adults[END_REF][START_REF] Tambs | Moderate effects of hearing loss on mental health and subjective well-being: results from the Nord-Trondelag Hearing Loss Study[END_REF]. Furthermore, longitudinal examinations of HL and depression are scant, and the findings thus far are also contradictory. A Taiwanese study showed that over 12 years, HL was associated with increased incidence of depression relative to matched controls [START_REF] Hsu | Increased risk of depression in patients with acquired sensory hearing loss: A 12-year follow-up study[END_REF].

Concomitantly, an increased rate of depression symptoms following the onset of HL has also been observed [START_REF] Kiely | Dual sensory loss and depressive symptoms: the importance of hearing, daily functioning, and activity engagement[END_REF]. Conversely, in a Dutch cohort, no relationship between HL and depression was found, although HL was associated with increased loneliness amongst men [START_REF] Pronk | Hearing status in older persons: a significant determinant of depression and loneliness? Results from the longitudinal aging study amsterdam[END_REF][START_REF] Pronk | Hearing Loss in Older Persons: Does the Rate of Decline Affect Psychosocial Health?[END_REF]. HL has also been shown to have a cross-sectional relationship with depression symptoms in a sample of older Norwegian adults, but this relationship was no longer significant after six years [START_REF] Cosh | The association amongst visual, hearing, and dual sensory loss with depression and anxiety over 6 years: The Tromso Study[END_REF]. Such variations in findings appear to reflect a range of methodological differences between studies. Notably, assessment and classification of depression has varied substantially across studies, with differential findings observed both cross-sectionally [START_REF] Gopinath | Depressive symptoms in older adults with hearing impairments: the Blue Mountains Study[END_REF] and longitudinally depending on the classification of depression outcome. Further methodological variations include assessment of HL [START_REF] Lee | Hearing impairment and depressive symptoms in an older chinese population[END_REF], adjustment for health or psychosocial covariates, and the average age of the sample, with the HL and depression relationships reportedly stronger amongst younger adults [START_REF] Tambs | Moderate effects of hearing loss on mental health and subjective well-being: results from the Nord-Trondelag Hearing Loss Study[END_REF].

Additional studies are thus needed to better ascertain the long-term relationship between HL and depression [START_REF] Contrera | Association of Hearing Impairment and Emotional Vitality in Older Adults[END_REF]. Moreover, comparison of depression diagnosis compared with presence of depression symptoms is needed to further clarify the currently inconsistent findings. Therefore, the present study aims to examine the association between HL with depression over 12 years amongst older adults, specifically examining depression outcome as both diagnosis of Major Depressive Disorder (MDD) and presence of elevated depression symptoms.

Methods

This study forms part of the SENSE-Cog multi-phase research programme, funded by the European Union Horizon 2020 programme. SENSE-Cog aims to promote mental well-being in older adults with sensory and cognitive impairments (http://www.sense-cog.eu/). The first work package of this project aims to better understand the links between sensory, cognitive and mental ill-health in older Europeans (Cosh et al., Forthcoming).

Sample

Participants were recruited as part of the multi-center Three-City study (The 3C Study Group, 2003), a population-based cohort of community-dwelling persons aged 65 years and over. Between 1999 and 2001, 9294 participants were recruited from the electoral rolls of three French cities (Bordeaux, Dijon and Montpellier). A standardized evaluation with a face-to-face interview, as well as clinical examinations were undertaken at baseline as well as 2-3 year intervals for up to 12 years (see Figure 1). Of the initial sample, 7560 (90.6%) participated in at least one wave of follow up over the 12-year period; 116 participants had died before the first follow-up and 1411 by the end of the 12-year period (for a detailed overview of 3C sampling and methods see The 3C Study Group, 2003). The study protocol was approved by the Ethical Committees of the University-Hospitals of Bicêtre and Nîmes (France) and written informed consent was obtained from each participant.

Depression Measures

The Mini International Neuropsychiatric Interview (MINI) [START_REF] Sheehan | The Mini-International Neuropsychiatric Interview (M.I.N.I.): the development and validation of a structured diagnostic psychiatric interview for DSM-IV and ICD-10[END_REF] assessed current MDD diagnosis, according to DSM-IV criteria. The MINI is a standardized and well validated diagnostic interview, which has been validated in France [START_REF] Lecrubier | The Mini International Neuropsychiatric Interview (MINI), a short diagnostic interview: reliability and validity according to the CIDI[END_REF]. The MINI was administered at baseline, as well as at 7, 10 and 12 years. Prevalent cases were defined as current MDD at baseline and incident cases were defined as those presenting with a new and current diagnosis of MDD at a follow-up visit.

Depression symptoms were assessed via the 20-item Centre for Epidemiology Studies-Depression Scale [START_REF] Radloff | The CESD Scale: A self-report depression scale for research in the general population[END_REF] at all follow-up points. The CESD is a wellvalidated and reliable self-report depression screening tool. The French version of the CESD has also been validated in a population of community dwelling French adults [START_REF] Morin | Psychometric properties of the Center for Epidemiologic Studies Depression Scale (CES-D) in French clinical and nonclinical adults[END_REF]. Items are rated on a 4 point scale indicating symptom frequency in the past week, with higher scores indicative of greater symptom severity. Participants with a score ≥16 were classified as having depression symptoms [START_REF] Lewinsohn | The symptomatic expression of major depressive disorder in adolescents and young adults[END_REF].

Hearing Measurement

Self-reported Hearing Loss was assessed during standardized face-to-face interview administrated by trained psychologists or nurses at each follow up time point. HL was determined by the response to the question "do you hear what is said in everyday conversation?" Participants were given four response categories (yes without difficulties; some difficulties hearing someone who speaks normally; difficulties hearing someone who speaks loudly; no/deafness). Mild HL was classified as self-reported difficulty understanding a conversation (normal or loud speaking) and severe HL was classified as self-reported deafness or inability to hear a conversation.

Covariates

Socio-demographic and health-related information was collected during the standardized interview. These included education level (elementary, secondary, higher education), monthly income (<€760, €760-2280, >€2280, withheld/missing), and marital status (married/de facto, single/widowed/divorced). Information regarding alcohol consumption (<10, 10-40, >40 grams per day), tobacco use (current-, past -, or non-smoker), and falls during the past 12 months was also obtained. A composite score representing functional ability was calculated based the Rosow-Breslau scale, the Lawton-Brody Brody Instrumental Activities of Daily living (IADL) scale and the Katz Index of Independence in Activities of Daily Living (categorized as autonomous; dependent for mobility; mobility and IADL limitations; and dependent in 3+ areas; missing) [START_REF] Barberger-Gateau | A hierarchical model of domains of disablement in the elderly: a longitudinal approach[END_REF]. History of myocardial infarction, diabetes (fasting glycemia≥7mmol/L and/or anti-diabetic treatment), and use of psychotropic medication in the past month (ATC classification codes: N05A-C, N06A-B) was obtained. During the medical examination blood pressure was measured using a digital electronic tensiometer OMRON M4. Hypertension was defined using the 140/90 mmHg threshold or treatment with blood-pressure lowering drugs (ATC codes: C02, C03, C07, C08). Cognitive functioning was also assessed using the Mini Mental State Examination (MMSE; <24 ≥24).

Statistical Analysis

Socio-demographic and health characteristics were compared according to sensory loss using chi-squares and one-way ANOVAs. Baseline associations between HL with both MDD diagnosis and depression symptoms (16+ CESD score) were examined using logistic regression analyses. The longitudinal associations between baseline HL and depression were examined using mixed logistic models [START_REF] Carriere | Choosing marginal or random-effects models for longitudinal binary reposnes: application to self-reported disability among older persons[END_REF]. Logistic mixed models take into account within-subject correlation and model the individual's evolutions of depression over time across the 12 years of follow-up. Logistic mixed models allow for the reversibility of outcomes, and are thus sensitive to remitted cases of depression, and are also robust to missing data. The effect of baseline HL on incident MDD in those free of MDD at baseline and the relationship of baseline HL with incident depression symptoms in those free of depression symptoms at baseline were examined.

For each analysis, three models were undertaken to provide a more comprehensive understanding of the relative impact of psychosocial and physical health covariates on the HL-depression relationship. Model 1 adjusted for sex, study center, and age; Model 2 further adjusted for known psychosocial covariates; education, income, marital status, and psychotropic medication; and Model 3 also adjusted for physical health; functional ability, falls in past 12 months, hypertension, diabetes, smoking, alcohol, cognitive function (MMSE), and myocardial infarction. We also systematically searched for potential interactions between HL with sex, income and education level. Analyses were conducted using SAS 9.4 (SAS Institute, Inc., Cary, NC).

Results

Of the 8344 participants with baseline hearing and depression data, 60.4% (n = 5043) were female and mean age was 74.2 (SD = 5.5) years. At baseline, prevalence of mild HL was 30.7% (n=2558) and 7.8% (n = 654) for severe HL. Those with HL were older, more likely to be male, less educated, more commonly a pastsmoker and in poorer physical health on all assessed covariates (see Table 1).

Baseline prevalence of MDD was 1.9% (n=154) with a further 202 (2.2%) cases of incident MDD over 12 years. At baseline 20.1% (n = 1679) reported depression symptoms, with a further 1484 (22.3%) reporting onset of depression symptoms over follow-up. Both those with MDD and depression symptoms were more likely to be female, and unmarried (<.001). Those reporting depression symptoms also consumed more alcohol and had a lower income (<.001).

At baseline (Table 2), mild but not severe HL was associated with MDD (OR = 1.51, 95% CIs 1.07-2.12; OR = 1.48 95% CIs 0.79-2.79; respectively) in all models, whereas both mild and severe HL were associated with depression symptoms (OR = 1.29 95% CIs 1.14-1.47; OR = 1.51 95% CIs 1.22-1.87; respectively). HL was not associated with incident MDD over 12 years (Table 3). On the other hand, both mild and severe HL were related to incident depression symptoms (OR = 1.36 95% CIs 1.15-1.61; OR = 1.69 95% CIs 1.15-2.30; respectively) in all models. No interactions were significant.

Discussion

This study contributes to the currently limited and equivocal literature examining the longitudinal relationship between HL and depression. Those with selfreported HL were more likely to have elevated depression symptoms and diagnosed MDD at baseline. Furthermore, mild and severe HL were also associated with incident depression symptoms over 12 years in those depression-free at baseline, however HL was to related to incident MDD.

Consistent with prior findings, our results showed a significant cross-sectional relationship between HL and depression [START_REF] Gopinath | Depressive symptoms in older adults with hearing impairments: the Blue Mountains Study[END_REF][START_REF] Lee | Hearing impairment and depressive symptoms in an older chinese population[END_REF], and both mild and severe HL thresholds were related to elevated depression symptoms.

Although differential relationships between HL and depression have been reported

depending on how depression was assessed [START_REF] Gopinath | Depressive symptoms in older adults with hearing impairments: the Blue Mountains Study[END_REF], associations between HL and MDD diagnosis have been less commonly explored [START_REF] Mener | Hearing loss and depression in older adults[END_REF]. Our results showed that mild HL was associated with MDD diagnosis. Results for severe HL were in the same direction, however, did not reach statistical significance. This may be due to a reduced statistical power owing to the lower numbers reporting severe HL. Furthermore, our results contribute to the small and contradictory evidence regarding the longitudinal association between HL and depression. Previous longitudinal studies examining severity of depression symptoms have found no association between HL and depression [START_REF] Pronk | Hearing status in older persons: a significant determinant of depression and loneliness? Results from the longitudinal aging study amsterdam[END_REF][START_REF] Cosh | The association amongst visual, hearing, and dual sensory loss with depression and anxiety over 6 years: The Tromso Study[END_REF], whereas difference in depression symptoms pre-and post-HL onset have been observed [START_REF] Kiely | Dual sensory loss and depressive symptoms: the importance of hearing, daily functioning, and activity engagement[END_REF]. Our findings highlight a significant longitudinal association between HL with presence of depression symptoms. Thus HL appears to be related to presence of elevated depression symptoms, rather than directly impinging on symptom severity.

Although an association between HL and incident MDD has been reported previously [START_REF] Hsu | Increased risk of depression in patients with acquired sensory hearing loss: A 12-year follow-up study[END_REF], we did not find an association with MDD. Differences in findings might be explained by the older mean age of our sample, with some evidence suggesting a stronger relationship between HL and depression in younger ages [START_REF] Tambs | Moderate effects of hearing loss on mental health and subjective well-being: results from the Nord-Trondelag Hearing Loss Study[END_REF]. Notably, although the result was non-significant, an increased OR for MDD was observed for severe HL. It is likely that due to the few cases of incident MDD, our lack of an association may be due to analyses being underpowered.

Our results further suggest that differences in prior findings are likely reflective of varying methods of assessing depression. We found that HL was associated over time with presence of elevated symptoms, rather than depression diagnosis. The relationship with presence of increased symptomatology but lack of an association with MDD might reflect that subsyndromal depression is more common in older adults than major depression [START_REF] Blazer | Depression in Late Life: Review and Commentary[END_REF]; with self-report depression measures (such as the CESD) frequently used in the sensory loss literature failing to distinguish between MDD and subsyndromal depression.

Notably, however, elevated depression symptoms or subsyndromal depression can result in poor outcomes including increased mortality rates (Pennix et al., 1999a) and suicidal ideation [START_REF] Geiselmann | Psychiatrists' diagnoses of subthreshold depression in old age: frequency and correlates[END_REF]. Subsyndromal depression substantially contributes to reduced quality of life, increased disability (Pennix et al., 1999b) and increased negative attitudes towards ageing (Chachamovich et al., 2008). Thus even in the absence of an MDD diagnosis, treatment and intervention for depression symptoms remain important in the elderly with HL. Given that depression symptoms often go unnoticed and undiagnosed in the elderly [START_REF] Teresi | Prevalence of depression and depression recognition in nursing homes[END_REF], and communication barriers frequently limit access to mental health support for those with HL [START_REF] Sheppard | The lived experience of depression among culturally Deaf adults[END_REF]Badger, 2010, Turner et al., 2007), targeted intervention may be beneficial for this population.

A reduction in the ability to carry out activities of daily living is a proposed mechanism contributing to the association between HL and depression [START_REF] Chou | Combined effect of vision and hearing impairment on depression in older adults: evidence from the English Longitudinal Study of Ageing[END_REF], however adjustment for functional abilities did not attenuate results. Odds ratios in our studies remained similar across levels of adjustment, suggesting that other common processes might better explain these relationships. Communication difficulties observed in HL [START_REF] Kiely | Dual sensory loss and depressive symptoms: the importance of hearing, daily functioning, and activity engagement[END_REF][START_REF] Mcdonnall | The effects of developing a dual sensory loss on depression in older adults: a longitudinal study[END_REF] may underlie the association with depression, especially through increased social isolation and loneliness [START_REF] Pronk | Prospective effects of hearing status on loneliness and depression in older persons: identification of subgroups[END_REF], Schneider et al., 2012); with perceived lack of social support associated with depression onset (Pennix et al., 1999b). Furthermore, reductions in help seeking [START_REF] Sheppard | The lived experience of depression among culturally Deaf adults[END_REF] and increases in comorbid anxiety [START_REF] Cosh | The association amongst visual, hearing, and dual sensory loss with depression and anxiety over 6 years: The Tromso Study[END_REF] might also contribute to the depression and HL relationship.

Strengths and Limitations

Strengths of this study include the length of follow up and large sample size.

Moreover, this study substantially contributes to the current HL and depression literature, not only by providing a rare longitudinal examination, but also by exploring depression both as an MDD diagnosis and as the presence of elevated depression symptoms. Such analysis allowed for increased insight into the nature of associations of HL and depression in older adults. Limitations include that HL was self-reported. Such self-reports may represent underestimates of actual HL, due to perceptions that hearing decline is a natural part of aging. Conversely, those who have depression might be more likely to self-report HL, or concentration deficits associated with depression might increase the likelihood of difficultly hearing a conversation.

Although, given that those with baseline depression were excluded from longitudinal analyses, it appears that the HL-depression association extends beyond only selfreporting bias. Although relationships remained significant after adjustment for cognitive functioning, the extent to which underlying cognitive decline might have influenced self-report HL and the ability to hear a conversation cannot be fully ascertained. Furthermore, from this study we cannot exclude the possibility that depression onset might have been a prodromal aspect of dementia. However, given the dearth of longitudinal studies of HL and depression, our findings contribute valuable insight, although ongoing research with objective assessments of HL would be invaluable to corroborate such associations.

Although a CESD cut off score of 16 has empirical support, there is also debate as to the most appropriate cut off score (see [START_REF] Vilagut | Screening for Depression in the General Population with the Center for Epidemiologic Studies Depression (CES-D): A Systematic Review with Meta-Analysis[END_REF]. Different thresholds may result in differences in findings. MDD was assessed only at three time points, thus additional MDD cases that may have occurred and remitted between assessments were not included. Our MDD results were also likely underpowered, especially for severe HL and we cannot be certain of the lack of associations.

Conclusion

Older adults with self-reported HL have poorer mental health outcomes, in particular subthreshold depression over time. Both mild and severe self-reported HL are associated with depression symptoms at baseline as well as over 12 years.

Especially given possible communication and help-seeking barriers in HL, increased focus on assessment and identification of depression, including subthreshold symptomatology, may be warranted to improve quality of life amongst older adults with HL. Concomitantly, improved identification and management of HL might crucially limit depression amongst older adults.

"SENSE-Cog has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 668648". The Three-City study is conducted under a partnership agreement between the Institut National de la Santé et de la Recherche Médicale (INSERM), the University Bordeaux 2 Victor Segalen and Sanofi-Aventis. The Fondation pour la Recherche Médicale funded the preparation and initiation of the study. The Three-City study is also supported by the Caisse Nationale Maladie des Travailleurs Salariés, Direction Générale de la Santé, MGEN, Institut de la Longévité, Conseils Régionaux d'Aquitaine et Bourgogne, Fondation de France, Ministry of Research-INSERM Programme "Cohortes et collections de données biologiques", Agence Nationale de la Recherche ANR PNRA 2006 and LongVie 2007, and the "Fondation Plan Alzheimer" (FCS 2009-2012).