domain: spi sde

text:
J M Abelleira-Pereira

G Escudero-Burgos

H Elayoubi

J J Mascarell

J P Serin

J Sánchez-Oneto

J R Portela

E Martínez De

L A Ossa

HYDROTHERMAL PROCESSING OF ISOPROPANOL-WATER SOLUTIONS AT MODERATE CONDITIONS IN A BATCH REACTOR: EXPERIMENTAL & PRELIMINARY SIMULATION

Keywords: Hydrothermal treatment, Isopropanol, Hydrogen, Batch, Simulation 2. Highlights

• Non-oxidative hydrothermal processing of high concentrated IPA-Water solutions is safe.

• Combustible gases produced at temperatures ≥ 300 °C and Hydrogen gas at ≥ 550 °C.

• Moderate to high organic matter removal yielded at 300 & 550 °C without catalyst or oxidant.

Purpose

Water itself and alcohols have been pointed out repeatedly in the literature as adequate solvents for reclaiming the carbon fibers contained in composite materials by hydrothermal liquefaction/solvolysis, although very few used isopropanol (IPA) [START_REF] Zhang | Current status of carbon fibre and carbon fibre composites recycling[END_REF][START_REF] Morin | Near-and supercritical solvolysis of carbon fibre reinforced polymers (CFRPs) for recycling carbon fibers as a valuable resource: State of the art[END_REF]. IPA is known to be a major component of the solution for cleaning/drying of wafers within the growing semiconductors manufacture industry; those solutions usually contain from 40 to 70 wt.% of IPA [START_REF] Lin | Recovery of IPA from waste solvent of a semiconductor plant[END_REF][START_REF] Park | Interfacial and electrokinetic characterization of IPA solutions related to semiconductor wafer drying and cleaning[END_REF]. So, wouldn´t it be profitable to use the wafers spent cleaning solution as solvent in the hydrothermal reclaim of carbon fibers? Ideally, that would mean the management and valorization (organic matter removal, waste to energy in the form of H2/CH4) of a spent waste (wafers cleaning solution) to recover a high added value material (carbon fibers from composite off-cuts or obsolete composite parts). Two major objectives are to be highlighted in this work, which was performed as a preliminary step in the framework of the Circular Economy applied to the reclaim of carbon fibers embedded in composite off-cuts from the aeronautical industry: on the one hand, it was necessary to understand and describe in situ by ourselves the behaviour of the high concentrated solvent mixture IPA-water under several hydrothermal conditions and liquid influent volumes of hundreds of millilitres for the sake of experimental safety and logistics; on the other hand, and as far as authors of this work are aware, no studies have been published on the simulation of hydrothermal processes in batch reactors up to this date, so we aimed here to propose a preliminary approach on that.

Materials and methods

Experiments were performed in a 1 liter PARR 4570 Series 316 stainless-steel non-stirred batch reactor, able to operate at 570 °C (accuracy ±3 °C) and pressures of up to 277 bara. Deionized water and pure IPA were used to develop the influent solutions (total initial volume (Vi) from 100 to 550 mL], ranging from 5 to 60 wt.% IPA. Prior to each test, and to assure that no oxygen was present during the experiments, the reactor was gently purged with nitrogen. Initial reactor pressure (Pi), required to reach the final testing pressure, was also attained using nitrogen (only required in one of the performed experiments). Temperature, pressure, and reaction time ranged from 250 to 550 °C, 125 to 250 bar, and 30 to 120 min, respectively. Liquid effluent was analyzed for pH, conductivity, chemical oxygen demand (COD) and total organic carbon (TOC). Composition of the gaseous effluent (H2, CO2, O2, N2, CH4, CO) was also analysed by GC, using helium as carrier gas. An attempt to simulate the entire experimental hydrothermal test was done using the modelling software Prosimbatch © . Prior to run the simulation, simplified and reasonable hypothesis were adopted.

Results and discussion

Hydrothermal operation (15 experiments + 4 replicates) was smooth and safe, without occurrence of any temperature or pressure spikes. The highest net increment of produced overall combustible gases pressure (10 bara) was attained in two of the tested conditions: 300 °C, 120 bara, IPA 40 wt.% (Vi = 400 mL), Pi, N2 = 1 bara, 120 min// 300 °C, 105 bara, IPA 20 wt.% (Vi = 450 mL), Pi, N2 = 1 bara, 120 min. However, in terms of Hydrogen Efficiency (HE = [((4*mol_CH4, OUT) + (2*mol_H2, OUT))/mol_H IN]*100) the results were negligible at those conditions and even when operating at 450 °C; only when operating at 550 °C a perceptible hydrogen production (HE = 16.75%) was achieved [550 °C, 230 bara, IPA 5 wt.% (Vi = 100 mL), Pi, N2 = 1 bara, 40 min]. Also, to be highlighted is the fact that no net increment of overall combustible gases pressure occurred when: 1.-operating with water-IPA 40 wt.% solutions at 250 °C, or 2.-operating with water-IPA 60 wt.% solutions at 300 °C. Regarding organic matter removal, considerable COD removals (71%) were only obtained when operating at 550 °C; nevertheless, we detected signs indicating that the operation at 300 °C, 150 bara, IPA 10 wt.% (Vi = 200 mL), Pi, N2 = 36.2 bara and 120 min can also yield a remarkable COD removal (74%). Finally, it is worth to mention that operating at 300 °C, IPA 40 wt.% (Vi = 200 mL), Pi, N2 = 37.4 bara and 120 min, a sudden and well-marked drop of temperature and pressure, followed by a temperature recovery and a unexpected and sharp, while controlled, increase of pressure (up to 196 bara) was detected after 15 min at 300 °C and 137 bara; according to our understanding and based on evidence in the literature [START_REF] Anikeev | Kinetics & thermodynamics of 2-propanol dehydration in SCW[END_REF], this phenomenon is related to the critical point of the particular influent mixture water-IPA-nitrogen employed in that test, and have an impact in the yielded results. Calculated evolution of the pressure is restored according to the initial raise in temperature from ambient to operating. Simulations were running with or without reactions.

Conclusions and perspectives

Non-oxidative hydrothermal batch process using IPA-Water solutions with considerably high concentrations of IPA is safe, either under sub-or supercritical water conditions. In general, temperatures over 500 °C were required for the significant production of Hydrogen gas. However, considerable net increment of produced overall combustible gases pressure and organic matter removal can be attained with lower temperatures, even 300 °C. Some hydrothermal tests can be simulated, but not all. This could be due to the change in the number of phases during the experiment. A plot of the phase envelope of simplified mixture seems to demonstrate that and it should be further investigated.


Faiza Saidj

Sid-Ahmed Rezzoug

Fatiha Bentahar

Chahrazed Boutekedjiret

Chemical Composition and Insecticidal Properties of Thymus numidicus (Poiret) Essential Oil from Algeria

Keywords: Thyme oil, Thymus numidicus (Poiret), chemical composition, insecticidal properties

Essential oils of thyme (Thymus numidicus (Poiret)) from Algeria were isolated by steam distillation, analysed by gas chromatography coupled with the mass spectrometry (GC-MS) and investigated for their insecticidal activities against Rhizopertha dominica. Contact toxicity of global oil recovered after one hour of extraction and its fraction F1 recovered after 2.5 minutes of extraction were tested using the filter paper method. Analysis of the essential oil made it possible to identify 14 components, representing 75.4 % of the oil. The major components were thymol (51.0 %) followed by carvacrol (9.4 %), linalool (3.3 %), thymolmethyl-ether (3.2 %) and iso-caryophyllene (2.7 %). The evolution of the yield and the composition of essential oil as function of time extraction show that steam distillation is a very rapid process and the duration of extraction could be limited to15 minutes, since more than 94 % of oil are extracted. The toxicity tests show that thyme oil and its fraction F1 have an insecticidal activity, nevertheless, the mortality obtained for global oil are weaker compared with those obtained for the F 1 fraction. This toxicity would be allotted to the presence instrong proportion of linalool and thymol.

Introduction: Empirical at the beginning, the crop protection knew enormous progress with the discovery of the pesticides of synthesis. However, their massive and irrational use in the fight against the devastating insects of the cultures generated perverse effects such as: the development of phenomena of resistance at the treated devastating insects 1,[START_REF] Bughio | Influence of malathion resistance status on survival and growth of Tribolium castaneum (Coleoptera: Tenebrionidae), when fed on flour from insectresistance and succeptible grain rice cultivars[END_REF] , the pollution of the biosphere, the presence of residues of pesticides in the treated agricultural produce reaching inadmissible contents. In front of the extent of the problem, the methods of fights must be reconsidered. These last years, work was oriented towards the search for biopesticides biodegradable to replace the conventional pesticides.The use of the plants like source of pesticides was the several work object [START_REF] Regnault-Roger | Insecticidal effect of essential oil from Mediterranean plants upon Acanthhoscelides obtectus Say (Coleoptera: Bruchidae), a pest of Kidney bean (Phaseolus vulgaris L.)[END_REF][START_REF] Huang | Bioactivities of safrol and iso-safrol on Sitophilus zeamais (Coleoptera: Curculionidae) and Tribolium castaneum (Coleoptera: Tenebrionidae)[END_REF][START_REF] Lale | Potential of combining neem (Azadirachta indica A. Juss) seed oil with varietal resistance for management of the cowpea bruchid, Callosobruchus maculates (F.)[END_REF][START_REF] Owusu | Effect of some Ghanaian plant component on control of two stored-product insect pests of cereal[END_REF] . Many plants are recognized to have insecticidal properties. Tapondjou et al. [START_REF] Tapondjou | Efficacy of powder and essential oil of Chenopodium ambrosioides leaves as post-harvest grain protectants against six stored prodict beetles[END_REF][START_REF] Tapondjou | Bioactivities of cymol and essential oil of Cupressus sempervirens and Eucalyptu ssaligna against Sitophilus zeamais Motschulsky and Tribolium confusum Duval[END_REF] and Bouda et al. [START_REF] Bouda | Effect of essential oils from leaves of Ageratum conyzoides, Lantana camara an Chromalaena odorata on the mortality of Sitophilus zeamais (Coleoptera Curculionidae)[END_REF] , showed the toxic effect of essential oils of several plants (Chenopodium ambrosioides (L), Eucalyptus saligna (Smith), Cupressus sempervirens (L), Ageratum conyzoides (L), Lantana camara (L.) and Chromolaena odorata (L.) against the stored food product insects. Keita et al.10, showed that essential oils as well as the powders of Ocimum basilicum(L.) and Ocimum gratissimum (L.) are toxic against Callosobruhus maculatus. According to Hummelbrunner and Isman 11, the components of many essential oils (thymol, carvacrol, trans-anethol, eugenol, 〈-terpineol) have a very high biocide effect on Spodoptera litura (Boisduval).

Thymus numidicus (Poiret) (Arabic Zaâteur) is an endemic species of Algerian and Tunisian North, Thymus kind of the family of Labiatea 12. Many studies were interested in the chemical composition of essential oil of thyme [START_REF] Rassooli | Inhibitory effects of thyme oils on growth and aflatoxin production by Aspergillus parasiticus[END_REF][START_REF] Baydar | Antibacterial activity and composition of essential oils from Origanum, Thymbra and Saturja spices with commercial importance in Turkey[END_REF][START_REF] Haddaf | Composition chimique et activité antifongique des huiles essentielles de Thymus vulgaris L. et de Thymus numidicus Poiret d'Algérie. 6e symposium international d'aromathérapie scientifique et plantes médicinales[END_REF][START_REF] Kabouche | Analysis of the essential oil of Thymus numidicus (Poiret) from Algeria[END_REF][START_REF] Hudaïb | GC-MS evaluation of thyme (Thymus vulgaris L.) oil composition and variation during the vegetative cycle[END_REF] like in its antibacterial [START_REF] Sagdic | Antibacterial activity of Turkish spice hydrosols[END_REF][START_REF] Burt | Essentials oils: their antibacterial proprieties and potential application in food -a review[END_REF] , antifungal19, antioxidant [START_REF] Benzi | Lipid peroxidation: a review of causes, consequences, measurement and dietary influences[END_REF][START_REF] Sokmen | The in vitro antimicrobial and antioxidant activities of the essential oils and methanol extracts of endemic Thymus spathulifolius[END_REF][START_REF] Tepe | Antioxidative activity of the essential oils of Thymus sipyleus subsp. Sipyleus var.sipyleus and Thymus sipyleus subsp. Sipyleus var.rosolans[END_REF] and insecticidal properties. The present study was initiated to investigate the chemical composition and the contact toxicity of essential oil of Thymus numidicus (Poiret) from Algeria against Rhizopertha dominica, insect devastating of cereals.

Experiment

Plant material and extraction of essential oil: The vegetal matter used was collected from "Yakouren, Tizi Ouzou" area located 150 km East of Algiers in April 2004 and identified according to the Flora of Algeria 12.The thyme oil was recovered by steam distillation. The experimental tests have been carried out in laboratory scale, during one hour. 35 g of dry plant (3.25 % of moisture, steam flow rate of 6.3 g min -1 ) was placed in a glass column, which the lower and higher parts were respectively connected to a steam generator and a condenser. The vapour produced by the steam generator crosses the plant, charged with essential oil then pass through the condenser to a receiving flask. The essential oil is collected, dried with anhydrous sodium sulphate and stored at 4°C until used. During distillation, plant was exposed to steam water at 100°C and 1 bar. Extractions were performed at least three times, and the mean values were reported. The essential oil yield was estimated according to the dry vegetal matter. The moisture was determined by the toluene distillation method [START_REF] Asta | Official Analytical Method[END_REF] . In addition, in order to follow the evolution by time of the yield of essential oil and the relative content of some major components of oil, the essential oil were collected at different extraction periods and analysed.

Analysis:

The essential oils were analysed by gas chromatography coupled to mass spectrometry (GC-MS) (Varian computerized system comprising a 3900 gas chromatograph coupled to a mass spectrometer model SATURN 2100 T) using two fused-silica-capillary columns with different stationary phases. The non-polar column was CP-Sil 8 (30m x 0.25mm x 0.25µm film thickness) and the polar one was a Stabilwax TM consisting of Carbowax TM . PEG (60m x 0.2mm x 0.25µm film thickness). GC-MS spectra were obtained using the following conditions: carrier gas He; flow rate 0.8 mL/min; split 1:30; injection volume 0.1 µL; injection temperature 220°C; oven temperature progress from 60°C during 10 min then rising to 250°C at 2°C/min and holding at 250°C for 20 min. The ionisation mode used was electronic impact at 70 eV. The relative percentage of the components was calculated from GC-FID peak areas. Identification of the components was based on comparison of their relative retention indices (RRI) on apolar and polar columns, determined with reference to an homologous series of C8-C28 n-alkanes, and by a comparison of their mass spectral fragmentation patterns with those stored in the data bank (Wiley/NBS library) and the literature [START_REF] Adams | Identification of essential oil components by Gas chromatography / Mass spectroscopy[END_REF] .

Insecticidal activity

Insects: Rhizopertha dominica were obtained from laboratory cultures maintained in the dark in incubator at 33°C and 70 % relative humidity.

Contact toxicity:

A serial dilution of the essential oil of thyme recovered after 2.5 min noted F1 fraction and global essential oil obtained after 1h was prepared in acetone. Contact toxicity was tested using filter paper impregnated method and the controls were determined using acetone. Filter papers (9.0 cm diameter) were impregnated with aliquots 5 ml of an appropriate concentration of essential oils or acetone (control). The filters were air dried for 5 min. 20 insects were confined to each filter paper within a glass ring (9.0 cm diameter, 1.5 cm). Fluon GPI was applied to the inner surface of each ring to prevent the insects from climbing onto the side of the ring. Five replicates were set up for each thyme oil concentrations and control. All insects were exposed to the filter paper treatment for 24 h, after which they were transferred to glass vial with culture media and kept in incubators at 33°C and 70 % relative humidity. Mortality was recorded daily until end-point mortality (when the number of dead insects no longer increased with time) was reached after 6 days. Data were transformed using Shneider-Orelli formula given by :

t t c M M M M - - = 100 (%)
Where Mc is the corrected insect mortality, M the insect mortality in the treated population of insect and Mt the insect mortality in the control.

Results and discussion

Composition of the essential oil: The thyme essential oil has a movable liquid aspect, yellow colour and a pleasant aromatic and slightly spice odour. Analysis of the essential oil by GC-MS made it possible to identify 14 components whose rate is higher than 0.1 %, representing 75.4 % of the oil. These results are given in Table 1. As shown in this table, it can be seen that this oil was characterised by an important content in the oxygenated compound. Thymol and carvacrol were the main compounds with 51.0 % and 9.4 % respectively; linalool and thymol-methyl-ether which are the second more abundant compounds are present respectively at 3.3 % and 3.2 % and p-cymene present with 0.5 %, is the only identified monoterpene. Among the identified sesquiterpenes, the isocaryophyllene is most abundant with 2.7 %.

The predominance of phenolic compounds is in agreement with previous results reported from T. numidicus essential oil from Constantine (North-Eastern of Algeria) [START_REF] Kabouche | Analysis of the essential oil of Thymus numidicus (Poiret) from Algeria[END_REF] mainly represented with thymol (68.2 %), carvacrol (16.9 %) and linalool (11.5 %); and T.numidicus essential oil from Berrahal (area located 500 km East of Algiers) [START_REF] Haddaf | Composition chimique et activité antifongique des huiles essentielles de Thymus vulgaris L. et de Thymus numidicus Poiret d'Algérie. 6e symposium international d'aromathérapie scientifique et plantes médicinales[END_REF] , which was characterized by thymol (60.8 %) as the major component, followed by linalool (8.0 %) and carvacrol (5.1 %). In addition, we notice that the amount of linalool in our sample is weaker than that of oils from Constantine and Berrahal, however it is comparable with that of oil from Souk-Ahras (area located 650 km East of Algiers) [START_REF] Haddaf | Composition chimique et activité antifongique des huiles essentielles de Thymus vulgaris L. et de Thymus numidicus Poiret d'Algérie. 6e symposium international d'aromathérapie scientifique et plantes médicinales[END_REF] characterized by thymol (25.4 %) and carvacrol (11.3 %) as the major component, followed by linalool (2.7 %).

The difference in the composition of essential thyme oil is very frequent. Faleiro et al. [START_REF] Faleiro | Antibacterial activity of the essential oils from Portuguese endemic spices of thymus[END_REF] report a similar behaviour for three Portuguese thymes (T. comphoratus, T. lotocephatus and T. mastichina) and by Rasooli and Abyanet [START_REF] Rassooli | Inhibitory effects of thyme oils on growth and aflatoxin production by Aspergillus parasiticus[END_REF] for two species of thyme collected in Iran (T. eriocalyx and T. x-porlock). Indeed, the climatic and environmental factors, the intensity of the metabolism of the plants, the species, the age and the part of plant, the period and the area of the gathering as well as the activity of the glandular hairs affect the synthesis and the secretion of oils.

Yield and essential oil composition as function of time:

The yield of essential oil obtained by the steam distillation is 2.06 %. This value is comparable with that given in the literature, especially with that given by Kabouche et al. 16 for T. numidicus from Djebel El-Ouahch mountain, Constantine. Evolution of essential oil yield as function of time, figure 1, shows that the extraction time is relatively short since at the end of one hour, we do not observe any more essential oil in the distillate. The yield increases quickly during the first 15 minutes were more than 94 % of essential oil are recovered. Thereafter, its evolution becomes slower; after 60 minutes, it is negligible. The analysis by gas chromatography of the oil recovered with regular time intervals enabled us to follow the evolution by time of the relative content of some major components of oil belonging to different chemical families : linalool, thymol-methyl-ether, thymol, carvacrol and iso-caryophyllene. As it is shown in table 2, we notice that the considered components are recovered in the ascending order of their boiling points. Indeed, the linalool and the thymol-methyl-ether were mostly recovered after 2.5 minutes of the extraction process with 8.2 % and 3.0 % respectively. The thymol reach their maximum contents (79.3 %) after five minutes of extraction and finally the carvacrol and iso-caryophyllene follows them after ten minutes of steam distillation with a maximum content of (12.2 %) and (4.2 %) respectively. The fact that the considered components are recovered in the ascending order of their boiling points lets suppose that the steam distillation depends on phenomena of transfer of the oil located at the surface of the plant and of its evaporation. Besides, the present study, showed an interest: this way of extracting the oil (fractionnement) allow obtaining the essential oil of different qualities enriched with particular components. It also may be used for analytical purposes or to avoid additional oil processing such as disterpenation and rectification. 3, its shows increase in the insect mortality with the concentrations of used solutions of essential oils. The mortality obtained for global oil are weaker compared with those obtained for the F1 fraction. For a concentration of 3.125 (%V) the oil recovered after 2.5 min involves a percentage of mortality of 86.73 % against 79.59 % for oil extracted after 1 hour; 94.86 % of mortality are obtained for a concentration of 12.5 (%V) in F1 fraction, whereas global essential oil causes only 87.69 %. These results show that the F1 fraction is more efficient against Rhizopertha dominica than the global oil. These behaviours could be explained by the content of major compounds of these oils (Table 4). Indeed, the percentage of thymol and linalool are more significant in F1 fraction, whereas the amount of thymol-methyl-ether and carvacrol is practically the same. These observations would suggest that toxicity by contact effect of F1 fraction would be allotted to the presence in strong proportion of linalool and thymol. Nevertheless, the additional tests using of the solutions of pure linalool and thymol and the mixtures with various concentrations are to be planned to confirm or cancel these assumptions.

Conclusion:

This study enabled us to determine the chemical composition of the essential oil of Thymus numidicus (Poiret) from Algeria, extracted by steam distillation and to evaluate its insecticidal activity and that of its fraction recovered after 2.5 minutes of extraction against Rhizopertha dominica, a devastating insect of cereals. Analysis of the essential oil by GC-MS made it possible to identify 14 components whose rate is higher than 0.1 %, representing 75.4 % of the oil. The major components were thymol (51.0 %) followed by carvacrol (9.4 %), linalool (3.3 %), thymol-methylether (3.2 %) and iso-caryophyllene (2.7 %). The evolution of the yield and the composition of essential oil as function of time extraction show that steam distillation is a very rapid process which seems to be regulated by essential oil evaporation phenomena from the superficial sites of the plant. In addition, the results obtained show that the duration of extraction could be limited to 15 minutes, since more than 94 % of oil are extracted. The toxicity tests show that thyme oil and its fraction F1 have an insecticidal activity. Indeed, the mortality of the insect increases with the concentration of oils used nevertheless, the mortality obtained for global oil are weaker compared with those obtained for the F1 fraction. This toxicity would be allotted to the presence in strong proportion of linalool and thymol. These results suggest that thyme oil and its fraction may be useful as a grain protecting with contact effect against Rhizopertha dominica and could replace synthetics insecticides.

Figure 1 .

 1 Figure 1. Evolution of the essential oil yield as function of time


Angéline Maillard

Alice Laniepce

Shailendra Segobin

Najlaa Lahbairi

Céline Boudehent

François Vabret

Nicolas Cabé

Dr Anne-Lise Pitel
email: anne-lise.pitel@unicaen.fr

PROGNOSTIC FACTORS FOR LOW-RISK DRINKING AND RELAPSE IN ALCOHOL USE DISORDER: A MULTIMODAL ANALYSIS

Keywords: Alcohol Use Disorder, cognition, low-risk drinking, neuroimaging, relapse, Treatment outcomes

Aims: To specify the determinants of low-risk alcohol drinking and relapse at different time points after detoxification in patients with severe Alcohol Use Disorder (AUD).

Methods: Fifty-four AUD patients and 36 healthy controls (HC) were evaluated early in abstinence (T1). They underwent clinical, neuropsychological and neuroimaging (structural MRI and 18 FDG-PET) investigations.

AUD patients were subsequently classified as "low-risk drinkers" (LR) or "relapsers" (R) based on their alcohol drinking at 6 months (T2) and one year (T3) after discharge, using their medical record or self-reported drinking estimation at follow-up.

Results: Based on the alcohol status at T2 and compared to HC, only R had alexithymia, lower gray matter volume in the midbrain and hypermetabolism in the cerebellum and hippocampi. Based on the alcohol status at T3 and compared to HC, only R had more severe nicotinic dependence, lower episodic and working memory performance, lower gray matter volume in the amygdala, ventromedial prefrontal cortex and anterior cingulate gyrus, and hypermetabolism in cerebellum, hippocampi and anterior cingulate gyrus. Moreover, R had bilateral frontal hypometabolism, whereas LR only presented right frontal hypometabolism.

Conclusion:

Nicotine dependence, memory impairments, and structural brain abnormalities in regions involved in impulsivity and decision-making might contribute to a one-year relapse. Treatment outcome at one year may also be associated with an imbalance between a hypermetabolism of the limbic system and a hypometabolism of the frontal executive system.

Finally, cerebellar hypermetabolism and alexithymia may be determinants of relapse at both 6 months and one year.

INTRODUCTION

Alcohol Use Disorder (AUD) is a highly prevalent public health problem with considerable individual and societal costs. It is defined by the National Institute on Alcohol Abuse and Alcoholism (NIAAA) as a chronic brain disease, characterized by a high rate of relapse [START_REF] Moos | Rates and predictors of relapse after natural and treated remission from alcohol use disorders[END_REF]. Several psychological and biological factors seem to increase the risk of relapse.

Among the psychological factors, alcohol craving (2), impulsivity [START_REF] Rupp | Impact of social cognition on alcohol dependence treatment outcome: Poorer facial emotion recognition predicts relapse/dropout[END_REF][START_REF] Barreno | Specific aspects of cognitive impulsivity are longitudinally associated with lower treatment retention and greater relapse in therapeutic community treatment[END_REF], altered emotion processing and interpersonal relationships [START_REF] Witkiewitz | Dynamic Association Between Negative Affect and Alcohol Lapses Following Alcohol Treatment[END_REF], smoking status [START_REF] Durazzo | Psychiatric, Demographic, and Brain Morphological Predictors of Relapse After Treatment for an Alcohol Use Disorder[END_REF] and comorbid psychiatric disorders [START_REF] Trocchio | The association between self-reported mental health status and alcohol and drug abstinence 5 years post-assessment for an addiction disorder in u.s. and swedish samples[END_REF] have frequently been related to alcohol relapse. Regarding the impact of cognitive alterations, results are less consistent. Some studies indicated that memory and executive deficits do not seem to be associated with a higher risk of relapse [START_REF] Pitel | Changes in the episodic memory and executive functions of abstinent and relapsed alcoholics over a 6month period[END_REF][START_REF] Manning | Neurocognitive functioning and treatment outcome following detoxification among asian alcohol-dependent inpatients[END_REF][START_REF] Moriyama | Executive dysfunction and clinical outcome in chronic alcoholics[END_REF], whereas others showed that processing speed, working memory and inhibition performance early in abstinence may distinguish future relapsers from abstainers [START_REF] Noël | Contribution of frontal cerebral blood flow measured by 99mTc-bicisate spect and executive function deficits to predicting treatment outcome in alcohol-dependent patients[END_REF][START_REF] Camchong | Resting-State Synchrony in Short-Term Versus Long-Term Abstinent Alcoholics[END_REF]. Concerning biological factors, structural brain alterations are frequently suggested as reliable relapse determinants [START_REF] Durazzo | Psychiatric, Demographic, and Brain Morphological Predictors of Relapse After Treatment for an Alcohol Use Disorder[END_REF][START_REF] Noël | Contribution of frontal cerebral blood flow measured by 99mTc-bicisate spect and executive function deficits to predicting treatment outcome in alcohol-dependent patients[END_REF][START_REF] Cardenas | Brain morphology at entry into treatment for alcohol dependence is related to relapse propensity[END_REF]. Despite the obvious multifactorial nature of relapse, few investigations used an integrative approach to identify prognostic indicators of treatment outcome by considering several clinical, neuropsychological as well as structural and functional brain measures within the same study.

Moreover, because the attrition rate is high in longitudinal studies of AUD and relapse frequently occurs within 6 months after detoxification [START_REF] Boothby | Acamprosate for the treatment of alcohol dependence[END_REF][START_REF] Witkiewitz | Predictors of heavy drinking during and following treatment[END_REF], studies usually examine determinant factors of an early relapse [START_REF] Manning | Neurocognitive functioning and treatment outcome following detoxification among asian alcohol-dependent inpatients[END_REF][START_REF] Noël | Contribution of frontal cerebral blood flow measured by 99mTc-bicisate spect and executive function deficits to predicting treatment outcome in alcohol-dependent patients[END_REF][START_REF] Pfefferbaum | Brain volumes, RBC status, and hepatic function in alcoholics after 1 and 4 weeks of sobriety: Predictors of outcome[END_REF][START_REF] Brower | Insomnia, selfmedication, and relapse to alcoholism[END_REF][START_REF] Rando | Association of frontal and posterior cortical gray matter volume with time to alcohol relapse: A prospective study[END_REF]. Studies including a later follow-up examination are scarce [START_REF] Moos | Rates and predictors of relapse after natural and treated remission from alcohol use disorders[END_REF][START_REF] Trocchio | The association between self-reported mental health status and alcohol and drug abstinence 5 years post-assessment for an addiction disorder in u.s. and swedish samples[END_REF]). Yet, relapse can be regarded as a dynamic process influenced by different determinants according to the time period. Further studies investigating determinants of early as well as later relapse are thus required.

The operational definition of relapse is difficult, changing and related to that of treatment success. Until recently, total abstinence from alcohol was considered as the only acceptable treatment target. However, new medications targeting a reduction of alcohol consumption reached the market and resulted in a paradigm shift. Even though abstinence remains often the safest treatment option, reduction of alcohol consumption is thus now considered as a relevant alternative. In this perspective, the World Health Organization (WHO) has defined four drinking risk levels (very high, high, medium, and low). The European Medicines Agency (EMA) considers that a two-level reduction in the WHO drinking risk levels can be used as a secondary endpoint for clinical trials [START_REF]Guideline on the Development of Medicinal Products for the Treatment of Alcohol Dependence[END_REF]. The NIAAA and the United States Dietary Guidelines Advice on Alcohol recommend limiting intake to two drinks in a day for men and one drink in a day for women.

In line with these new AUD treatment outcomes, the objective of the present study was to specify the determinants of low-risk drinking and relapse at different time points. We conducted a multimodal analysis by exploring several clinical, neuropsychological and neuroimaging measures in early detoxified AUD patients. Two follow-up examinations were conducted six months and one year after the discharge in order to specify, at each time point, the risk level associated with alcohol drinking. There was no neuropsychological nor neuroimaging assessment at follow-up.

METHOD Participants

Fifty-four AUD patients and 36 healthy controls (HC) were included in this study approved by the local ethics committee of Caen University Hospital (CPP Nord-Ouest III, no. IDRCB: 2011-A00495-36). To be included, participants had to have French as their native language, to be between 18 and 70-year-old, and to have at least 8 years of schooling.

Comorbid conditions such as psychiatric disorders, a history of serious chronic disease, or neurological pathologies were exclusion criteria. Participants did not fulfill the criteria for substance use disorder (other than alcohol for AUD patients) except tobacco. Participants gave their informed written consent to the study prior to their inclusion. The study was carried out in line with the declaration of Helsinki (1964).

AUD patients were recruited by clinicians while they were receiving withdrawal treatment as inpatients at Caen University Hospital. They met both criteria for severe AUD (DSM-5) [START_REF]Diagnostic and Statistical Manual of Mental Disorders, 5th Edition. Diagnostic and Statistical Manual of Mental Disorders[END_REF]. At inclusion, none of them presented physical symptoms of alcohol withdrawal as assessed by the Cushman's scale [START_REF] Cushman | Alcohol Withdrawal Syndromes: Clinical Management with Lofexidine[END_REF] and none of them were under psychotropic treatments (in particular, benzodiazepines used during the alcohol withdrawal treatment were stopped at least 48h before inclusion). The three-week detoxification program usually included one week of withdrawal treatment and two weeks of daily treatment sessions adjusted to the patients' cognitive abilities. The daily sessions included psychoeducation, motivational interview, group therapy or relapse prevention treatment based on cognitive behavioral therapy.

HC were recruited to match the demographics (age, sex, and education) of the AUD patients. They were interviewed with the Alcohol Use Disorder Identification Test (AUDIT) [START_REF] Gache | The Alcohol Use Disorders Identification Test (AUDIT) as a Screening Tool for Excessive Drinking in Primary Care: Reliability and Validity of a French Version[END_REF] to ensure that they did not meet the criteria for alcohol abuse (AUDIT<7 for men and <6 for women). None of the controls had a score at the Beck Depression Inventory (BDI) superior to 29 [START_REF] Beck | Manual for the Beck depression inventory-II[END_REF] and a Mini-Mental State Examination score inferior to 26 [START_REF] Folstein | Mini-mental state". A practical method for grading the cognitive state of patients for the clinician[END_REF].

Demographical and clinical data are presented in Table 1 and in supplementary Table S1.

Table 1 about here

Study Design

A baseline clinical, neuropsychological and neuroimaging assessment was conducted early in abstinence (11.04 ± 4.34 days after the last alcohol drink, T1). Alcohol status was determined at six months (T2) and one year (T3) after discharge. Based on recommendations of the NIAAA or the "Dietary guidelines for Americans 2020-2025", patients were classified, at both T2 and T3, as "low-risk drinkers" (LR) when they had consumed no more than 14 drinks/week for men and 7 drinks/week for women, and "relapsers" (R) when their alcohol consumption exceeded these thresholds or when they reported to have lost the control of their consumption (without being able to quantify it with accuracy) during the follow-up period.

For X patients, we also used medical records indicating hospital admission, notably in the emergency department, for alcohol intoxication. We also questioned patients about potential binge drinking behavior, which is characterized by the consumption of an excessive amount of alcohol in a short period of time. Bingers were not included in the LR group. In this study one standard drink is equivalent at 10 grams of pure ethanol. Based on their alcohol status at each time point (T2 or T3), patients were classified as LR T2 or R T2 , and LR T3 or R T3 .

Clinical evaluation

At baseline (T1), all participants completed standardized questionnaires that evaluated alcohol consumption (AUDIT), depression symptoms (BDI), anxiety symptoms (State-Trait Anxiety Inventory; STAI) [START_REF] Spielberger | State-Trait Anxiety Inventory for Adults Sampler Set Manual, Instrument and Scoring Guide[END_REF], nicotine dependence (Fagerstrom) [START_REF] Heatherton | The Fagerström Test for Nicotine Dependence: a revision of the Fagerstrom Tolerance Questionnaire[END_REF], impulsivity (Barratt Impulsiveness Scale; BIS 11) [START_REF] Patton | Barratt Impulsiveness Scale[END_REF] and alexithymia (Toronto Alexithymia Scale; TAS-20) [START_REF] Bagby | The twenty-item Toronto Alexithymia scale-II. Convergent, discriminant, and concurrent validity[END_REF].

The highest Cushman score experienced during the withdrawal period [START_REF] Cushman | Alcohol Withdrawal Syndromes: Clinical Management with Lofexidine[END_REF], the number of previous alcohol detoxifications, the amount of alcohol consumed the month preceding the withdrawal (number of units of 10g of pure ethanol per day), and the duration of heavy drinking (years) were collected by clinicians.

Neuropsychological examination

At baseline, patients performed neuropsychological tasks to evaluate episodic memory, working memory, executive functions, attention and visuoconstruction. Working memory. The backward digit span of the WAIS-III [START_REF] Wechsler | WAIS-III administration and scoring manual[END_REF] was used.

Flexibility. The number of perseverative errors of the Modified Card Sorting Test (MCST) [START_REF] Cianchetti | Modified Wisconsin Card Sorting Test: proposal of a supplementary scoring method[END_REF] was used.

Inhibition. The interference score of the Stroop test [START_REF] Stroop | Studies of interference in serial verbal reactions[END_REF], corresponding to the difference between the time needed to complete the interference condition (Word-Color condition) and the time needed for the denomination condition (Color condition), was used.

Attention. The overall performance index (GZ-F) of the d2 test [START_REF] Bates | The d2 test of attention: Construct validity and extensions in scoring techniques[END_REF] was used.

Visuoconstruction. The copy score of the ROCF was used.

Brain Imaging examination

While the entire sample (N=36) of HC underwent all the neuroimaging investigations at baseline (T1), MRI was conducted in only 47 AUD patients, and FDG-PET in 37 AUD patients (out of the 54 AUD patients in total). Acquisitions and preprocessing of brain imaging data are provided in supplementary material Method S1.

Statistical analyses

Demographical, clinical, and neuropsychological data.

Given the sample sizes and the fact that several variables were not normally distributed (according to Shapiro-Wilk's tests), non-parametric tests were used.

First, we compared the entire group of AUD patients to HC by means of Mann-Whitney's tests carried out on the data collected at T1. We then conducted between-group comparisons based on alcohol status at T2 and T3 separately. Group effects (R vs. LR vs. HC) were thus analyzed using Kruskal-Wallis's tests. When significant, post-hoc pairwise comparisons were performed to compare R vs. LR, R vs. HC, and LR vs. HC using Dwass-Steel-Critchlow-Fligner tests (DSCF). Given the number of comparisons carried out, we used Bonferroni's corrections. Regarding the analyses of the main effects (Mann-Whitney's test and Kruskal-Wallis's tests), we used p<0.003 for the analyses conducted on 14 demographical and clinical variables (0.05/14=0.003) and p<0.007 for the 7 neuropsychological variables (0.05/7=0.007). For post-hoc comparisons, the statistical threshold was set to p<0.05.

Brain imaging data.

Analyses were performed in SPM 12 using a minimum cluster size of k=60 for MRI data and k=25 for PET data, both corresponding to a cluster size of approximately 200 mm 3 . First, voxel-based two-sample t-tests were conducted to compare gray matter (GM) and white matter (WM) volumes, as well as metabolism between the entire group of AUD patients and HC on the T1 data. Then, these analyses were conducted based on alcohol status at T2 and T3 separately. Voxel-based two-sample t-tests were carried out to compare GM and WM volumes, as well as metabolism between R vs. LR, R vs. HC, and LR vs. HC. For each comparison, the two contrasts were systematically analyzed. For all neuroimaging comparisons, age was used as a covariate, and for volumetric comparisons, total intracranial volume was also included in the analysis. Analyses were first conducted using an uncorrected p<0.001 threshold. Then, a more stringent threshold corrected for multiple comparisons (Family-Wise Error (FWE), p<0.05) was applied to highlight the most significant findings.

Significant clusters of gray matter volumes and metabolism were labeled using the Harvard-Oxford cortical and subcortical structural, and the probabilistic cerebellar atlases implemented in FSL (fsl.fmrib.ox.ac.uk/fsl/fslwiki/Atlases). White matter clusters were labelled using the MRI Atlas of Human White Matter [START_REF] Oishi | MRI Atlas of Human White Matter[END_REF].

RESULTS

Comparisons between AUD patients and HC at T1

AUD patients differed significantly from HC on the BDI (U=249, p<0.001), STAI-B (U=363, p<0.001), TAS-20 (U=522, p=0.001), Fagerstrom (U=360, p<0.001), proportion of smokers (X2=21.642, p<0.001), and AUDIT (U=0, p<0.001) scores (Table1).

Compared to HC, AUD patients were impaired on verbal episodic memory (U=508, p<0.001), working memory (U=487, p<0.001), inhibition (U=611, p=0.006), and attention (U=529, p<0.001) (Table 2 and supplementary Table S2). Neuroimaging data are presented in Figure S1.

Alcohol status at follow-up

At T2 (6 months): Among the 54 patients who completed the baseline assessment, alcohol status was obtained for 42 patients, including 27 who self-reported their alcohol consumption by phone and 15 for whom information was collected in available medical records. Among these 42 patients, 27 were classified as R T2 and 15 as LR T2 based on their alcohol consumption during the 6-month follow-up. Thirty six of these 42 patients underwent the MRI examination (24 R T2 and 12 LR T2 ). Thirty one of those 36 also had the FDG-PET examination (20 R T2 and 11 LR T2 ) at T1 (Figure 1). Among the 15 LR T2 , 9 patients were abstainers: 6 of them had undergone the MRI and 5 the FDG-PET examination.

Regarding demographical, clinical, neuropsychological, and neuroimaging data at baseline, patients who could not be reached at follow-up did not differ from the 42 patients for whom alcohol status was obtained at T2. At T3 (one year): Among the 42 patients of T2, alcohol status was obtained at T3 for 41 patients (20 self-reported their alcohol consumption during a clinical interview, and data were collected in available medical records for the other 21). Alcohol status was obtained, based on available medical records, for one more patient for whom no information regarding alcohol status was available at T2. Among these 42 patients, 33 were classified as R T3 , and 9 as LR T3 according to their alcohol consumption during the one-year follow-up. Thirty six of the 42 patients underwent the MRI examination (29 R T3 and 7 LR T3 ). Thirty one of those 36 also had the FDG-PET examination (25 R T3 and 6 LR T3 ) at T1 (Figure 1). Among the 9 LR T3 , 5 patients were abstainers: 3 of them had undergone the MRI and 2 the FDG-PET examination.

Regarding demographical, clinical, neuropsychological, and neuroimaging data, patients who could not be reached at follow-up did not differ from the 42 patients for whom alcohol status was obtained at T3.

Figure 1 about here

Comparisons between HC, R T2 , and LR T2 on data acquired at T1

Demographical and clinical data

A group effect was found for the BDI, STAI-B, Fagerstrom, AUDIT, and TAS-20 scores (all p<0.001). Compared with HC, both patient groups (LR T2 and R T2 ) had higher scores on the BDI, STAI-B, Fagerstrom, and AUDIT, but did not differ from each other. On the TAS 20, only R T2 significantly differed from HC (Table 1 and Table S1).

Neuropsychological data

A group effect was found for the verbal episodic memory, working memory (p=0.003 in both cases), and attention (p=0.004) scores only. Compared with HC, both patient groups (R T2 and LR T2 ) were impaired on verbal episodic memory and working memory. For attention, only LR T2 significantly differed from HC (Table 2 and supplementary Table S2).

Neuroimaging data

Results are presented in Figure 2.

Gray matter. Compared to LR T2 , R T2 had lower GM volume in the right lingual gyrus (p<0.001 uncorrected). There were no significant results using an FWE correction (p<0.05).

Compared to HC, R T2 had widespread GM alteration (p<0.001 uncorrected). Using a more stringent threshold (FWE, p<0.05), GM shrinkage remained significant in large brain clusters including parts of the frontal, parietal, temporal (including medial temporal lobes namely hippocampi and parahippocampal gyri), occipital, insular, and cingulate cortices as well as in the cerebellum, and in subcortical structures such as the thalami, hypothalami (including mammillary bodies), amygdala, and caudate nuclei.

Compared to HC, LR T2 showed smaller volume of GM bilaterally in the frontal, cingulate (anterior and middle), temporal (including medial temporal lobes namely hippocampi and parahippocampal gyri), parietal, occipital, and insular cortices, as well as in the caudate nuclei, thalami, and hypothalami (including mammillary bodies), and in the left amygdala, lobule 6 and crus I of the cerebellum (p<0.001 uncorrected). We found no significant results using an FWE correction (p<0.05).

The opposite contrasts did not reveal any significant difference.

White matter. Compared to LR T2 , R T2 had lower WM volume in the right cingulum, body and splenium of the corpus callosum, and posterior corona radiata (p<0.001 uncorrected). There were no significant results using an FWE correction (p<0.05).

Compared to HC, R T2 had widespread WM volume reduction (p<0.001 uncorrected). When a more stringent threshold was applied (FWE, p<0.05), WM shrinkage remained significant in large clusters including parts of the midbrain, fornix, corpus callosum, corona radiata, thalamic radiation, superior fronto-occipital fasciculus, superior longitudinal fasciculus, internal capsule, right cerebral peduncle, left cingulum and in the WM of the middle frontal gyri.

LR T2 showed smaller volume than HC in the WM of the frontal gyri, corpus callosum, corona radiata, posterior thalamic radiation, superior fronto-occipital fasciculus, retrolenticular part of the internal capsule, superior longitudinal fasciculus, in the left cingulum, and anterior limb of internal capsule (p<0.001, uncorrected). We found no significant results using an FWE correction (p<0.05).

The opposite contrasts did not reveal any significant difference.

Metabolism. At T1, there was no significant difference between R T2 and LR T2 regarding the regional glucose metabolism (p<0.001 uncorrected).

Compared to HC, R T2 had hypometabolism bilaterally in the medial, middle, and superior frontal gyri, as well as in the left paracingulate gyrus, and in the right inferior parietal lobule (p<0.001 uncorrected). The opposite contrast revealed that R T2 also had bilateral hypermetabolism in lobules V-VIII, Crus I and II of the cerebellum, as well as in the temporal gyri (including parahippocampal gyri and hippocampi), right precentral gyrus, and in the left postcentral gyrus (p<0.001 uncorrected).

Compared to HC, LR T2 had hypometabolism in the bilateral inferior parietal lobule, and in the superior and middle frontal gyri (p<0.001 uncorrected). The opposite contrast showed that LR T2 also had hypermetabolism in the left middle temporal gyrus only (p<0.001 uncorrected).

None of the comparisons remained significant using an FWE correction (p<0.05).

Comparisons between HC, R T3 , and LR T3 on data acquired at T1

Demographical and clinical data

A group effect was found for the BDI, STAI-B, AUDIT, Fagerstrom, and TAS-20 scores (all p<0.001). Compared with HC, both patient groups (R T3 and LR T3 ) had higher scores on the BDI, STAI-B, and AUDIT, but did not differ from each other. On the Fagerstrom and TAS 20, only R T3 differed significantly from HC (Table 1 and Table S1).

Neuropsychological data

A group effect was found for the verbal episodic memory and working memory scores only (p=0.003 in both cases), with R T3 being impaired compared with HC (Table 2 and supplementary Table S2).

Neuroimaging data

Results are presented in Figure 3.

Gray matter. At T1, there was no group difference in GM volume between R T3 and LR T3 (p<0.001 uncorrected).

The comparison between R T3 and HC revealed a similar pattern of shrinkage as the one observed for the comparison between R T2 and HC using both statistical thresholds (p<0.001 uncorrected and FWE correction (p<0.05)).

LR T3 showed smaller GM volume than HC bilaterally in the insula, hippocampi, thalami, middle frontal, precuneus, lingual, parahippocampi, and Heschl gyri, as well as in the right postcentral, precentral, inferior and superior frontal gyri (p<0.001 uncorrected). The analysis did not reveal any significant difference after FWE correction (p<0.05).

Opposite contrasts revealed no significant differences in any of the comparisons.

White matter. R T3 had lower WM volume than LR T3 in the right posterior corona radiata, as well as in the body and splenium of corpus callosum, and in the WM of the cingulate gyrus (p<0.001 uncorrected). Using an FWE correction (p<0.05), the analysis did not reveal any significant difference.

Comparisons between R T3 and HC revealed a similar pattern of results to that observed for the comparison between R T2 and HC using both statistical thresholds (p<0.001 uncorrected and FWE correction (p<0.05)). LR T3 showed smaller volume than HC in the WM of the frontal gyri, genu and body of the corpus callosum, anterior corona radiata, right posterior thalamic radiation, left anterior limb of internal capsule, posterior corona radiata, and superior fronto-occipital fasciculus (p<0.001 uncorrected). We found no significant results using an FWE correction (p<0.05).

Opposite contrasts revealed no significant differences in any of the comparisons.

Metabolism. At T1, there was no significant difference of metabolism between R T3 and LR T3 (p<0.001 uncorrected).

Compared to HC, R T3 had hypometabolism bilaterally in the medial, middle and superior frontal gyri, in the paracingulate gyri, and in the right inferior parietal lobule (p<0.001 uncorrected). The opposite contrast revealed similar pattern of hypermetabolism to that observed for the comparison between R T2 and HC. R T3 had also hypermetabolism in the anterior cingulate gyri (p<0.001 uncorrected).

Compared to HC, LR T3 had hypometabolism in the right middle frontal gyrus (p<0.001 uncorrected). The opposite contrast showed that LR T3 also had hypermetabolism in the left middle temporal gyrus (p<0.001 uncorrected).

None of the comparisons remained significant using an FWE correction (p<0.05).

DISCUSSION

The objective of the present study was to specify the determinants of low-risk drinking (no more than 14 drinks/week for men and 7 drinks/week for women) and relapse at different time points after detoxification. For this purpose, clinical, neuropsychological and neuroimaging data, collected in early detoxified AUD inpatients, were compared according to the alcohol status of these AUD patients six months and one year after the baseline assessment. Our findings indicate that future relapsers and low-risk drinkers had different profiles of alexithymia, nicotine dependence, memory deficits, and volumetric and metabolic brain alterations measured early in abstinence. Except for alexithymia and cerebellar hypermetabolism, which can be regarded as prognostic factors for relapse at both six months and one year, the determinants of relapse were different for the two time points.

First, results of the present study revealed that alexithymia and neuroimaging alterations observed after alcohol withdrawal were the main determinants of treatment outcome at six months since they made possible to distinguish patients who would relapse from those who would be able to maintain low-risk alcohol consumption. In effect, only patients subsequently classified as relapsers at six months presented alexithymia traits, suggesting that patients who had difficulties in identifying and describing their emotions may be more susceptible to relapse within the first 6 months following the detoxification. This finding is consistent with previous studies reporting that negative affect and emotion processing deficits increase the risk of early relapse [START_REF] Rupp | Impact of social cognition on alcohol dependence treatment outcome: Poorer facial emotion recognition predicts relapse/dropout[END_REF][START_REF] Witkiewitz | Dynamic Association Between Negative Affect and Alcohol Lapses Following Alcohol Treatment[END_REF][START_REF] Berking | Deficits in emotion-regulation skills predict alcohol use during and after cognitive-behavioral therapy for alcohol dependence[END_REF]. Alcohol consumption is indeed sometimes used as a coping strategy to regulate emotional states and altered interpersonal relationships [START_REF] Kornreich | Impaired Emotional Facial Expression Recognition Is Associated With Interpersonal Problems in Alcoholism[END_REF][START_REF] Hoffman | Neurophysiological and Interpersonal Correlates of Emotional Face Processing in Alcohol Use Disorder[END_REF]. In addition, a recent study showed that social cognition deficits, including emotion recognition and affective responsiveness, did not spontaneously recover during the first months of abstinence [START_REF] Rupp | Do Social Cognition Deficits Recover with Abstinence in Alcohol-Dependent Patients?[END_REF]. Taken together, these findings highlight the relevance of developing therapeutic interventions to manage emotional deficits and ultimately reduce the risk of relapse.

Our study also highlighted that early in abstinence, patients who subsequently relapsed within the six months after alcohol withdrawal had a more severe loss of GM and WM volume than those who managed to maintain a low-risk drinking. This more pronounced shrinkage affected brain regions including notably the frontal, parietal, and cingulate cortices, insula, as well as hippocampi and thalami, which all have already been related to relapse in previous studies [START_REF] Durazzo | Psychiatric, Demographic, and Brain Morphological Predictors of Relapse After Treatment for an Alcohol Use Disorder[END_REF][START_REF] Cardenas | Brain morphology at entry into treatment for alcohol dependence is related to relapse propensity[END_REF][START_REF] Wu | Accelerated repetitive transcranial magnetic stimulation does not influence grey matter volumes in regions related to alcohol relapse: An open-label exploratory study[END_REF]. Because these regions are cortical and subcortical nodes of the executive control and salient networks [START_REF] Seeley | Dissociable intrinsic connectivity networks for salience processing and executive control[END_REF], this finding suggests that patients who relapsed may not have been able to integrate sensory, emotional and cognitive information in order to control alcohol use and to maintain alcohol drinking at a low-risk level.

Another possible determinant of relapse at six months is the presence of a cerebellar hypermetabolism. Interestingly, this pattern of glucose metabolism, which we had previously interpreted as a maladaptive plasticity phenomenon within the cerebellum [START_REF] Ritz | Cerebellar Hypermetabolism in Alcohol Use Disorder: Compensatory Mechanism or Maladaptive Plasticity?[END_REF], has only been found in patients who relapsed.

The originality of the present investigation is to enable us to specify the determinants of relapse and low-risk drinking at two time-points thanks to a follow-up examination one year after alcohol withdrawal. In addition to alexithymia, that also appears a determinant of treatment outcome at one year, this study is in line with previous investigations showing a link between the severity of nicotine dependence early in abstinence and relapse [START_REF] Durazzo | Psychiatric, Demographic, and Brain Morphological Predictors of Relapse After Treatment for an Alcohol Use Disorder[END_REF][START_REF] Chiappetta | Predictors of quit attempts and successful quit attempts among individuals with alcohol use disorders in a nationally representative sample[END_REF]. In agreement, a preclinical study showed that the use of nicotine restores alcohol-seeking behaviors in rats free from this substance [START_REF] Lê | Nicotine increases alcohol selfadministration and reinstates alcohol seeking in rats[END_REF]. Alcohol and tobacco are highly comorbid behaviors and cross-substance craving have frequently been shown [START_REF] Grant | Prevalence and co-occurrence of substance use disorders and independent mood and anxiety disorders: Results from the national epidemiologic survey on alcohol and related conditions[END_REF]. The use of one of these substances can indeed act as a conditioned cue for the use of the other one. The nicotinic acetylcholine receptor system is assumed to play a role in the alcohol reward circuit, probably through a cholinergic excitatory input in the mesolimbic system [START_REF] Kee | How can we use our knowledge of alcohol-tobacco interactions to reduce alcohol use?[END_REF]. This is in accordance with the fact that in our study, only patients who relapsed during the year following the withdrawal presented an atrophy of the midbrain and the amygdala (regions of the mesolimbic system) early after detoxification. Taken together, these findings suggest the relevance of conducting a combination of nicotine and alcohol withdrawal.

Contrary to a previous investigation conducted in our laboratory but in a different pool of AUD patients (8), we showed that verbal episodic memory impairments may be a determinant of a one-year relapse since only future relapsers exhibited such deficits early in abstinence. Memory impairments may hamper patients to remember the negative consequences of alcohol use or the situations in which they are at risk of relapse, and lead to low level of motivation to change drinking behavior [START_REF] Berre | Cognitive barriers to readiness to change in alcohol-dependent patients[END_REF]. This would result in the activation of automatic drinking behaviors and would thus make patients with episodic memory deficits more likely to relapse [START_REF] Bates | A role for cognitive rehabilitation in increasing the effectiveness of treatment for alcohol use disorders[END_REF]. Moreover, in accordance with previous studies [START_REF] Noël | Contribution of frontal cerebral blood flow measured by 99mTc-bicisate spect and executive function deficits to predicting treatment outcome in alcohol-dependent patients[END_REF][START_REF] Camchong | Resting-State Synchrony in Short-Term Versus Long-Term Abstinent Alcoholics[END_REF], only future relapsers had lower working memory performance than controls. On the opposite, results did not show that flexibility or inhibition might influence the relapse. Previous results are inconsistent [START_REF] Pitel | Changes in the episodic memory and executive functions of abstinent and relapsed alcoholics over a 6month period[END_REF][START_REF] Manning | Neurocognitive functioning and treatment outcome following detoxification among asian alcohol-dependent inpatients[END_REF][START_REF] Moriyama | Executive dysfunction and clinical outcome in chronic alcoholics[END_REF][START_REF] Noël | Contribution of frontal cerebral blood flow measured by 99mTc-bicisate spect and executive function deficits to predicting treatment outcome in alcohol-dependent patients[END_REF][START_REF] Camchong | Resting-State Synchrony in Short-Term Versus Long-Term Abstinent Alcoholics[END_REF] regarding the prognostic value of executive deficits. Such discrepancy may be related to the different neuropsychological tasks employed in these studies. They may not all be sensitive to the executive processes potentially underlying relapse. Impaired response inhibition evaluated with a go/no-go task [START_REF] Camchong | Resting-State Synchrony in Short-Term Versus Long-Term Abstinent Alcoholics[END_REF] or the Hayling test [START_REF] Noël | Contribution of frontal cerebral blood flow measured by 99mTc-bicisate spect and executive function deficits to predicting treatment outcome in alcohol-dependent patients[END_REF] was related to a high rate of relapse. A recent investigation (4) used both a go/no-go task and the Stroop test, also used in the present study. The results showed that the go/no-go task, which assesses the behavioral executive component, was associated with relapse, whereas the Stroop test, which assesses the cognitive executive component, was unrelated to treatment outcomes. These results underly how crucial it is to use neuropsychological tests that are more appropriate to identify AUD patients at risk of relapse.

Finally, early after detoxification, future relapsers at both 6 months and one year differ from future low-risk drinkers regarding the pattern of brain alterations. It was not surprising to find the same neuroimaging determinants for T2 and T3 given that the group assignments differed only for 6 individuals. In effect, even though direct group comparisons between R and LR did not provide any significant results after FWE corrections, potentially related to the small sample sizes, the patterns of alterations compared with controls were different for each patient group. Specific brain regions such as the amygdala, the ventromedial prefrontal cortex and the anterior cingulate gyrus are damaged only in patients who will relapse. These brain regions sustain functions such as decision-making or impulsive behaviors, which have already been linked to premature treatment dropout and relapse [START_REF] Barreno | Specific aspects of cognitive impulsivity are longitudinally associated with lower treatment retention and greater relapse in therapeutic community treatment[END_REF]. When patients act with impulsiveness and tend to prefer the immediate reward of alcohol consumption ignoring the 19 negative long-term consequences, they are more likely to relapse. This finding is consistent with our PET results. Future relapsers exhibited a bilateral frontal hypometabolism associated with hypermetabolism in anterior cingulate gyri and hippocampi, whereas future low-risk drinkers only presented frontal hypometabolism in the right hemisphere. Hypermetabolism in the hippocampi and anterior cingulate gyri, two regions involved in the limbic circuit [START_REF] Catani | A revised limbic system model for memory[END_REF], might reflect an overactivation of emotional responses, which may be difficult to control because of frontal hypometabolism. This overactivation of limbic/emotional system associated to an underactivation of the frontal/executive system would result in uncontrolled alcohol consumption and relapse (50). To our knowledge, the present study is the first to consider glucose metabolism early in abstinence as a potential determinant of relapse. Future studies with larger sample size are needed to confirm whether this profile of glucose metabolism can be considered as prognostic factors for relapse.

The main limitation of the present study is the sample size (especially for neuroimaging data) and notably the difference regarding the sample size of the group of relapsers compared with the low-risk drinkers. In effect, the small number of low-risk drinkers, particularly at the one-year follow-up, decreases the statistical power. Relatively low statistical power may affect the results of the structural comparisons with relapsers. However, this difference in the sample size reflects the clinical reality, with only 20 to 40% of AUD patients maintaining abstinence or controlled alcohol drinking over a year after detoxification [START_REF] Moos | Rates and predictors of relapse after natural and treated remission from alcohol use disorders[END_REF]. Moreover, in this study, the small sample of women hinders considering the sex difference. Another limitation relates to the multifactorial nature of relapse. Even though we considered simultaneously several factors in the same sample of patients, other factors such as social cognition abilities or functional connectivity measures may also be relevant prognostic factors for treatment outcome. Furthermore, as indicated in the introduction, the operational definition of relapse is difficult, changing and related to that of treatment success. The relapse measure we chose was conservative and it was difficult to retrospectively collect alcohol consumption data with accuracy. This lack of accuracy did not allow us to conduct analyses using the WHO drinking risk levels. However, our findings are consistent with a recent study that used the WHO drinking risk levels. This study showed that eight months after discharge, GM volumes of AUD patients who had reduced alcohol consumption by two-levels were comparable to those of abstainers. On the contrary, AUD patients who exhibited high-risk alcohol consumption had significantly lower thalamic and frontal volumes than abstainers and low-risk drinkers [START_REF] Meyerhoff | Not All Is Lost for Relapsers: Relapsers With Low WHO Risk Drinking Levels and Complete Abstainers Have Comparable Regional Gray Matter Volumes[END_REF]. Further studies are required to replicate our findings using other definitions of relapse. Finally, there was also a great heterogeneity among patients classified as relapsers, some of them being just above the NIAAA threshold while others exhibiting binge drinking behaviors and/or being back to uncontrolled alcohol consumption.

To conclude, the present study highlights that early in abstinence, several measures could have a prognostic value regarding the six-month (mid-term) and one-year (long-term) treatment outcome in terms of low-risk drinking and relapse. The nicotine dependence, memory impairments, structural and metabolic brain damage (except cerebellar hypermetabolism), especially in the reward circuit and limbic system, may be regarded as specific determinants of a long-term relapse. Alexithymia and cerebellar hypermetabolism may be prognostic factors for both mid-term and long-term relapse. This will be crucial to consider in future research since most of these determinants can be therapeutic targets to consider in clinical practice. From a clinical perspective, future relapse risk assessments would ideally include an evaluation of the nicotine dependence, emotional disorder, episodic and working memory, as well as executive abilities. Regarding treatment, it appears relevant to combine alcohol detoxification program with smoking cessation, a treatment of emotional deficits, as well as cognitive rehabilitation.

  Verbal episodic memory. The delayed free recall of a French version of the Free and Cued Selective Reminding Test (FCSRT) (29) was used. Visual episodic memory. The 30-minute delayed recall of the Rey-Osterrieth Complex Figure (ROCF) (30) was used.

Figure 2

 2 Figure 2 about here.

Figure 3

 3 Figure 3 about here.

Median [ 1

 1 st -3 rd quartiles] are reported Using Mann-Whitney's tests, significant difference at p < 0.003 between AUD and HC are in bold a : Kruskal-Wallis ANOVA (except for the proportion of smokers: Chi 2 test); significant results at p < 0.003 are in bold b : Dwass-Steel-Critchlow-Fligner post-hoc comparisons or Mann-Whitney's tests when no data were available in the HC group; 1) Comparisons between R and LR; 2) Comparisons between R and HC; 3) Comparisons between LR and HC; significant results at p < 0.05 are in bold c : an alcohol unit = a standard drink = 10 g of pure ethanol Note: AUDIT = Alcohol Use Disorder Identification Test; BDI = Beck Depression Inventory; BIS = Barratt Impulsiveness Scale; MD = Missing data; STAI = State-Trait Anxiety Scale; TAS = Toronto Alexithymia Scale; AUD = Alcohol Use Disorder; HC = Healthy controls; LR = Low-risk drinkers; R = Relapsers.

Figure 1 :

 1 FIGURES LEGENDS

Figure 2 :

 2 Figure 2: Structural and metabolic abnormalities in relapsers (R) and low-risk drinkers (LR) compared with healthy controls (HC) based on alcohol status at 6 months (T2) Results are presented using a threshold of p < 0.001, uncorrected for multiple comparisons (k=60 for MRI data and k=25 for PET data). Ø: no significant results. Color bars represent Tvalues. Abbreviations: HC = Healthy controls; LR = Low-risk drinkers; R = Relapsers.

Figure 3 :

 3 Figure 3: Structural and metabolic abnormalities in relapsers (R) and low-risk drinkers (LR) compared with healthy controls (HC) based on alcohol status at one year (T3) See legend of Figure 2.

Table 2

 2 about here.

Table 2 . Neuropsychological performance (raw data) in each group and between-group 606 comparisons 607

 2

Fundings

This study was funded by Fondation pour la Recherche Medicale (FMR, ING20140129160), ANR-Retour post-doctorant 2010, Conseil Regional Basse Normandie, and MILDECA.

Authors contribution

ALP and FV were responsible for the study concept and design. AL, CB, NL, FV, and NC contributed to the acquisition. AM, SS, and ALP assisted with data analysis and interpretation of finding. AM draft the manuscript. AL, SS, CB, NC, and ALP provided critical revision of the manuscript for important intellectual content. All authors critically reviewed content and approved final version for publication. [START_REF] Noël | Contribution of frontal cerebral blood flow measured by 99mTc-bicisate spect and executive function deficits to predicting treatment outcome in alcohol-dependent patients[END_REF][START_REF] Camchong | Resting-State Synchrony in Short-Term Versus Long-Term Abstinent Alcoholics[END_REF][START_REF] Cardenas | Brain morphology at entry into treatment for alcohol dependence is related to relapse propensity[END_REF][START_REF] Boothby | Acamprosate for the treatment of alcohol dependence[END_REF][START_REF] Witkiewitz | Predictors of heavy drinking during and following treatment[END_REF][START_REF] Pfefferbaum | Brain volumes, RBC status, and hepatic function in alcoholics after 1 and 4 weeks of sobriety: Predictors of outcome[END_REF][START_REF] Brower | Insomnia, selfmedication, and relapse to alcoholism[END_REF][START_REF] Rando | Association of frontal and posterior cortical gray matter volume with time to alcohol relapse: A prospective study[END_REF][START_REF]Guideline on the Development of Medicinal Products for the Treatment of Alcohol Dependence[END_REF][START_REF]Diagnostic and Statistical Manual of Mental Disorders, 5th Edition. Diagnostic and Statistical Manual of Mental Disorders[END_REF][START_REF] Cushman | Alcohol Withdrawal Syndromes: Clinical Management with Lofexidine[END_REF][START_REF] Gache | The Alcohol Use Disorders Identification Test (AUDIT) as a Screening Tool for Excessive Drinking in Primary Care: Reliability and Validity of a French Version[END_REF] N/A 1) p=0.170

Number of previous detoxifications