Orbitofrontal structural markers of negative affect in alcohol dependence and their associations with heavy relapse-risk at 6 months post-treatment

BACKGROUND

Alcohol relapse is often occurring to regulate negative affect during withdrawal. On the neurobiological level, alcoholism is associated with gray matter (GM) abnormalities in regions that regulate emotional experience such as the orbitofrontal cortex (OFC). However, no study to our knowledge has investigated the neurobiological unpinning of affect in alcoholism at early withdrawal and the associations of OFC volume with long-term relapse risk.

METHODS

One hundred and eighty-two participants were included, 95 recently detoxified alcohol dependent patients (ADP) and 87 healthy controls (HC). We measured affective states using the positive and negative affect schedule (PANAS). We collected T1-weighted brain structural images and performed Voxel-based morphometry (VBM).

RESULTS

Findings revealed GM volume decrease in alcoholics in the prefrontal cortex (including medial OFC), anterior cingulate gyrus, and insula. GM volume in the medial OFC was positively associated with NA in the ADP group. Cox regression analysis predicted that risk to heavy relapse at 6 months increases with decreased GM volume in the medial OFC.

CONCLUSIONS

Negative affect during alcohol withdrawal was positively associated with OFC volume. What is more, increased GM volume in the OFC also moderated risk to heavy relapse at 6 months. Reduced GM in the OFC poses as risk to recovery from alcohol dependence and provides valuable insights into transient negative affect states during withdrawal that can trigger relapse. Implications exist for therapeutic interventions signifying the OFC as a neurobiological marker to relapse and could explain the inability of ADP to regulate internal negative affective states.

Genetic Contribution to Alcohol Dependence: Investigation of a Heterogeneous German Sample of Individuals with Alcohol Dependence, Chronic Alcoholic Pancreatitis, and Alcohol-Related Cirrhosis

The present study investigated the genetic contribution to alcohol dependence (AD) using genome-wide association data from three German samples. These comprised patients with: (i) AD; (ii) chronic alcoholic pancreatitis (ACP); and (iii) alcohol-related liver cirrhosis (ALC). Single marker, gene-based, and pathway analyses were conducted. A significant association was detected for the ADH1B locus in a gene-based approach (puncorrected = 1.2 × 10-6; pcorrected = 0.020). This was driven by the AD subsample. No association with ADH1B was found in the combined ACP + ALC sample. On first inspection, this seems surprising, since ADH1B is a robustly replicated risk gene for AD and may therefore be expected to be associated also with subgroups of AD patients. The negative finding in the ACP + ALC sample, however, may reflect genetic stratification as well as random fluctuation of allele frequencies in the cases and controls, demonstrating the importance of large samples in which the phenotype is well assessed.

Frontostriatal Connectivity During Reward Anticipation

Abstract. Neurobiological research indicates that altered reward processing is among the most promising risk mechanisms in alcohol use disorder and depression. To elucidate differences and similarities between both disorders, we investigated clinical patients and at-risk individuals in two studies using a functional magnetic resonance imaging (fMRI) monetary reward paradigm. In the first study, alcohol use disorder patients compared to depressed and healthy individuals showed increased activation of the ventral striatum during reward anticipation. In contrast, both patient groups showed reduced frontostriatal connectivity compared to controls. In the second study, at-risk comorbid individuals showed decreased activation in the dorsal striatum along with decreased frontostriatal connectivity. While the connectivity results replicate the common pattern found for the patient groups, the activation results indicate a more depression-related pattern in individuals prone to developing both disorders. In conclusion, frontostriatal connectivity might be a promising transdiagnostic marker for depression, alcohol use disorder, and their comorbidity.

Frontal cortex gray matter volume alterations in pathological gambling occur independently from substance use disorder

Neuroimaging in pathological gambling (PG) allows studying brain structure independent of pharmacological/neurotoxic effects occurring in substance addiction. Because of high comorbidity of PG with substance use disorder (SUD), first results on structural deficits in PG are controversial. The current investigation is the first to examine gray matter (GM) volume alterations in PG controlling for the impact of SUD by comparing non-comorbid (PG_PURE ) and two comorbid (PG_ALCOHOL and PG_POLY ) groups. Two hundred and five individuals were included in the analysis: 107 patients diagnosed with PG and 98 healthy controls (HCs). We employed voxel-based morphometry to look for GM volume differences between the groups controlling for age, smoking and depression. GM decreases in the superior medial and orbital frontal cortex occur independently of substance use in PG_PURE compared with HCs. The frontal pattern of GM decrease was comparable with PG_ALCOHOL group where additionally GM volume was decreased in the anterior cingulate but increased in the amygdala. Moreover, regions in PG_{ALCOHOL + POLY} with reduced GM volume were the medial frontal, anterior cingulate and occipital lobe regions. PG_{ALCOHOL + POLY} not only exhibited structural deficits in comparison with HCs but also relative to PG_PURE in the precuneus and post-central gyrus. We demonstrated specific frontal cortex GM deficits in PG without SUD comorbidities. Whereas some target regions reported in earlier studies might result from comorbid substance abuse, there seems to be a core set of frontal alterations associated with addicted gambling behaviour independent of toxic substance effects.

Striatal activation and frontostriatal connectivity during non-drug reward anticipation in alcohol dependence

According to prevailing neurobiological theories of addiction, altered function in neural reward circuitry is a central mechanism of alcohol dependence. Growing evidence postulates that the ventral striatum (VS), as well as areas of the prefrontal cortex, contribute to the increased incentive salience of alcohol-associated cues, diminished motivation to pursue non-drug rewards and weakened strength of inhibitory cognitive control, which are central to addiction. The present study aims to investigate the neural response and functional connectivity underlying monetary, non-drug reward processing in alcohol dependence. We utilized a reward paradigm to investigate the anticipation of monetary reward in 32 alcohol-dependent inpatients and 35 healthy controls. Functional magnetic resonance imaging was used to measure task-related brain activation and connectivity. Alcohol-dependent patients showed increased activation of the VS during anticipation of monetary gain compared with healthy controls. Generalized psychophysiological interaction analyses revealed decreased functional connectivity between the VS and the dorsolateral prefrontal cortex in alcohol dependent patients relative to controls. Increased activation of the VS and reduced frontostriatal connectivity were associated with increased craving. These findings provide evidence that alcohol dependence is rather associated with disrupted integration of striatal and prefrontal processes than with a global reward anticipation deficit.

Internet Addiction and the Virtual Self-image

Background

Internet gaming disorder appears to be associated with self-concept deficits and increased identification with one's avatar. For increased social network use, the few existing studies suggest striatal-related positive social feedback as an underlying factor. Furthermore, few study findings indicate that internet addicts generally have problems in emotional inhibitory control processing.

Methods

Pathological and addicted internet gamers as well as social network users were compared with healthy controls regarding psychometric and neurobiological measures of self-concept-related characteristics, avatar identification and emotional inhibitory control processing.

Results and conclusion

Psychometric results indicated that both subgroups showed higher self-concept deficits compared to healthy controls. Neurobiologically, different brain activation patterns were observed in the subgroups during self-knowledge retrieval and inhibition of emotional stimuli. Furthermore, addicted internet gamers showed a higher identification with the own avatar, mirrored in an increased left angular gyrus activation, a region functionally associated with identification processing and feelings of empathy.

These findings provide a starting point for the deduction of specific psychotherapeutic treatment approaches for addicted internet gamers and social network users.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Genomewide Association Study of Alcohol Dependence Identifies Risk Loci Altering Ethanol-Response Behaviors in Model Organisms

BACKGROUND

Alcohol dependence (AD) shows evidence for genetic liability, but genes influencing risk remain largely unidentified.

METHODS

We conducted a genomewide association study in 706 related AD cases and 1,748 unscreened population controls from Ireland. We sought replication in 15,496 samples of European descent. We used model organisms (MOs) to assess the role of orthologous genes in ethanol (EtOH)-response behaviors. We tested 1 primate-specific gene for expression differences in case/control postmortem brain tissue.

RESULTS

We detected significant association in COL6A3 and suggestive association in 2 previously implicated loci, KLF12 and RYR3. None of these signals are significant in replication. A suggestive signal in the long noncoding RNA LOC339975 is significant in case:control meta-analysis, but not in a population sample. Knockdown of a COL6A3 ortholog in Caenorhabditis elegans reduced EtOH sensitivity. Col6a3 expression correlated with handling-induced convulsions in mice. Loss of function of the KLF12 ortholog in C. elegans impaired development of acute functional tolerance (AFT). Klf12 expression correlated with locomotor activation following EtOH injection in mice. Loss of function of the RYR3 ortholog reduced EtOH sensitivity in C. elegans and rapid tolerance in Drosophila. The ryanodine receptor antagonist dantrolene reduced motivation to self-administer EtOH in rats. Expression of LOC339975 does not differ between cases and controls but is reduced in carriers of the associated rs11726136 allele in nucleus accumbens (NAc).

CONCLUSIONS

We detect association between AD and COL6A3, KLF12, RYR3, and LOC339975. Despite nonreplication of COL6A3, KLF12, and RYR3 signals, orthologs of these genes influence behavioral response to EtOH in MOs, suggesting potential involvement in human EtOH response and AD liability. The associated LOC339975 allele may influence gene expression in human NAc. Although the functions of long noncoding RNAs are poorly understood, there is mounting evidence implicating these genes in multiple brain functions and disorders.

Cortical surface-based threshold-free cluster enhancement and cortexwise mediation

Threshold-free cluster enhancement (TFCE) is a sensitive means to incorporate spatial neighborhood information in neuroimaging studies without using arbitrary thresholds. The majority of methods have applied TFCE to voxelwise data. The need to understand the relationship among multiple variables and imaging modalities has become critical. We propose a new method of applying TFCE to vertexwise statistical images as well as cortexwise (either voxel- or vertexwise) mediation analysis. Here we present TFCE_mediation, a toolbox that can be used for cortexwise multiple regression analysis with TFCE, and additionally cortexwise mediation using TFCE. The toolbox is open source and publicly available (https://github.com/trislett/TFCE_mediation). We validated TFCE_mediation in healthy controls from two independent multimodal neuroimaging samples (N = 199 and N = 183). We found a consistent structure-function relationship between surface area and the first independent component (IC1) of the N-back task, that white matter fractional anisotropy is strongly associated with IC1 N-back, and that our voxel-based results are essentially identical to FSL randomise using TFCE (all P_FWE <0.05). Using cortexwise mediation, we showed that the relationship between white matter FA and IC1 N-back is mediated by surface area in the right superior frontal cortex (P_FWE  < 0.05). We also demonstrated that the same mediation model is present using vertexwise mediation (P_FWE  < 0.05). In conclusion, cortexwise analysis with TFCE provides an effective analysis of multimodal neuroimaging data. Furthermore, cortexwise mediation analysis may identify or explain a mechanism that underlies an observed relationship among a predictor, intermediary, and dependent variables in which one of these variables is assessed at a whole-brain scale. Hum Brain Mapp 38:2795-2807, 2017. © 2017 Wiley Periodicals, Inc.

Low μ-Opioid Receptor Status in Alcohol Dependence Identified by Combined Positron Emission Tomography and Post-Mortem Brain Analysis

Blockade of the μ-opioid receptor (MOR) by naltrexone reduces relapse risk in a subpopulation of alcohol-dependent patients. Previous positron-emission-tomography (PET) studies using the MOR ligand [¹¹C]carfentanil have found increased MOR availability in abstinent alcoholics, which may reflect either increased MOR expression or lower endogenous ligand concentration. To differentiate between both effects, we investigated two cohorts of alcoholic subjects using either post-mortem or clinical PET analysis. Post-mortem brain tissue of alcohol-dependent subjects and controls (N=43/group) was quantitatively analyzed for MOR ([³H]DAMGO)-binding sites and OPRM1 mRNA in striatal regions. [¹¹C]carfentanil PET was performed in detoxified, medication free alcohol-dependent patients (N=38), followed by a randomized controlled study of naltrexone versus placebo and follow-up for 1 year (clinical trial number: NCT00317031). Because the functional OPRM1 variant rs1799971:A>G affects the ligand binding, allele carrier status was considered in the analyses. MOR-binding sites were reduced by 23-51% in post-mortem striatal tissue of alcoholics. In the PET study, a significant interaction of OPRM1 genotype, binding potential (BP_ND) for [¹¹C]carfentanil in the ventral striatum, and relapse risk was found. Particularly in G-allele carriers, lower striatal BP_ND was associated with a higher relapse risk. Interestingly, this effect was more pronounced in the naltrexone treatment group. Reduced MOR is interpreted as a neuroadaptation to an alcohol-induced release of endogenous ligands in patients with severe alcoholism. Low MOR availability may explain the ineffectiveness of naltrexone treatment in this subpopulation. Finally, low MOR-binding sites are proposed as a molecular marker for a negative disease course.

A Brief Outline of the Use of New Technologies for Treating Substance Use Disorders in the European Union

BACKGROUND

Clinicians in the field of drug addiction have started to exploit the growth of Technology-Based Interventions (TBIs). However, there is little information on how health personnel evaluate them.

METHODS

Semi-structured interviews were conducted among 20 European experts.

RESULTS

All of the interviewees recognised TBIs as a valuable tool to improve the management of substance-use disorders (SUDs). Most interviewees indicated that combining both traditional face-to-face therapist-patient clinic appointment with TBIs is probably the most effective method. Most interviewees agree that TBIs are valuable tools to overcome both physical and social barriers, and hence significantly facilitate the access to treatment. Poor infrastructure and lack of digital literacy are recognised as major barriers to the diffusion of these tools.

CONCLUSIONS

The application of various forms of technology in SUD treatment is an interesting development for the European Union. Technical and non-technical barriers exist and impede their full exploitation.

Functional neuroimaging effects of recently discovered genetic risk loci for schizophrenia and polygenic risk profile in five RDoC subdomains

Recently, 125 loci with genome-wide support for association with schizophrenia were identified. We investigated the impact of these variants and their accumulated genetic risk on brain activation in five neurocognitive domains of the Research Domain Criteria (working memory, reward processing, episodic memory, social cognition and emotion processing). In 578 healthy subjects we tested for association (i) of a polygenic risk profile score (RPS) including all single-nucleotide polymorphisms (SNPs) reaching genome-wide significance in the recent genome-wide association studies (GWAS) meta-analysis and (ii) of all independent genome-wide significant loci separately that showed sufficient distribution of all allelic groups in our sample (105 SNPs). The RPS was nominally associated with perigenual anterior cingulate and posterior cingulate/precuneus activation during episodic memory (P_FWE(ROI)=0.047) and social cognition (P_FWE(ROI)=0.025), respectively. Single SNP analyses revealed that rs9607782, located near EP300, was significantly associated with amygdala recruitment during emotion processing (P_FWE(ROI)=1.63 × 10^-4, surpassing Bonferroni correction for the number of SNPs). Importantly, this association was replicable in an independent sample (N=150; P_FWE(ROI)<0.025). Other SNP effects previously associated with imaging phenotypes were nominally significant, but did not withstand correction for the number of SNPs tested. To assess whether there was true signal within our data, we repeated single SNP analyses with 105 randomly chosen non-schizophrenia-associated variants, observing fewer significant results and lower association probabilities. Applying stringent methodological procedures, we found preliminary evidence for the notion that genetic risk for schizophrenia conferred by rs9607782 may be mediated by amygdala function. We critically evaluate the potential caveats of the methodological approaches employed and offer suggestions for future studies.

[On the legalization debate of non-medical cannabis consumption : Position paper of the German Association for Psychiatry, Psychotherapy and Psychosomatics]

Calls are increasing for the legalization of cannabis. Some legal experts, various politicians, political parties and associations are demanding a change in drug policy. The legalization debate is lively and receiving wide coverage in the media. The German Association for Psychiatry, Psychotherapy and Psychosomatics (DGPPN) comments on the most important questions from a medical scientific perspective: can cannabis consumption trigger mental illnesses, what consequences would legalization have for the healthcare system and where is more research needed?

The association of pineal gland volume and body mass in obese and normal weight individuals: a pilot study

BACKGROUND

In obese individuals impaired sleep and neuroendocrine alterations such as melatonin deficits are associated with circadian rhythm disruption, altered circadian clock gene expression, and bright light at night. While the relation of pineal gland volume (PGV) and melatonin levels has recently been documented in humans, surprisingly little is known about the possible interference of the PGV and the pathophysiology of obesity in humans.

SUBJECTS AND METHODS

We therefore compared the PGV of obese with non-obese individuals; both groups were matched by age and gender. Volumetric analyses were performed on the basis of 3 Tesla high resolution Magnetic Resonance Imaging (MRI).

RESULTS

We found, that the PGV was significantly smaller in obese individuals than in lean controls (P=0.036). Moreover, PGV and waist-hip ratio showed a significant negative association in controls (P=0.018, r^s=-0.602) whereas no association of both variables was found in obese individuals (P=0.856, r^s=-0.051).

CONCLUSIONS

Thus, the current pilot investigation suggests that pineal gland function, reflected by PGV might be involved in the energy homeostasis and pathophysiological mechanisms that contribute to the development and the maintenance of obesity in humans. Moreover, our data supports the notion that the replacement of melatonin deficits might be a novel strategy in the treatment of obesity.

GATA4 variant interaction with brain limbic structure and relapse risk: A voxel-based morphometry study

Atrial natriuretic peptide (ANP) receptors are highly expressed in the amygdala, caudate and hypothalamus. GATA4 gene encodes a transcription factor of ANP associated with the pathophysiology of alcohol dependence. We have previously demonstrated that the GATA4 single nucleotide polymorphism (SNP) rs13273672 revealed stronger alcohol-specific amygdala activation associated with lowered relapse risk to heavy drinking at 90 days in the AA-homozygotes. Our understanding however with respect to GATA4 variation on gray matter (GM) regional amygdala, caudate and hypothalamus volume is limited. We investigated GM differences specific to GATA4 and hypothesized that GM alterations will be predictive of heavy relapse. Eighty-three recently detoxified alcohol dependent patients were included. Neuroimaging data was analyzed using Voxel Based Morphometry (VBM). The main effects of GM volume and genotype as well as their interaction effect on time to heavy relapse (60 and 90 days) were analyzed using cox regression. Significant higher GM volume was found for the AA-genotype group compared with AG/GG-genotype in the hypothalamus and caudate. A significant interaction was revealed between caudate and amygdala GM volume and GATA4 genotype on time to heavy relapse. The interaction was expressed by means of higher GM in the AA genotype group to be associated with reduced risk to relapse whereas in the AG/GG group higher GM was associated with increased risk to relapse. This is the first report on GM regional volume alterations specific to GATA4 genotype [(SNP) rs13273672] and its association with relapse in alcohol dependence. Current findings further support the role of GATA4 in alcoholism.

Exploring the Neural Basis of Avatar Identification in Pathological Internet Gamers and of Self-Reflection in Pathological Social Network Users

Background and aims Internet gaming addiction appears to be related to self-concept deficits and increased angular gyrus (AG)-related identification with one's avatar. For increased social network use, a few existing studies suggest striatal-related positive social feedback as an underlying factor. However, whether an impaired self-concept and its reward-based compensation through the online presentation of an idealized version of the self are related to pathological social network use has not been investigated yet. We aimed to compare different stages of pathological Internet game and social network use to explore the neural basis of avatar and self-identification in addictive use. Methods About 19 pathological Internet gamers, 19 pathological social network users, and 19 healthy controls underwent functional magnetic resonance imaging while completing a self-retrieval paradigm, asking participants to rate the degree to which various self-concept-related characteristics described their self, ideal, and avatar. Self-concept-related characteristics were also psychometrically assessed. Results Psychometric testing indicated that pathological Internet gamers exhibited higher self-concept deficits generally, whereas pathological social network users exhibit deficits in emotion regulation only. We observed left AG hyperactivations in Internet gamers during avatar reflection and a correlation with symptom severity. Striatal hypoactivations during self-reflection (vs. ideal reflection) were observed in social network users and were correlated with symptom severity. Discussion and conclusion Internet gaming addiction appears to be linked to increased identification with one's avatar, evidenced by high left AG activations in pathological Internet gamers. Addiction to social networks seems to be characterized by emotion regulation deficits, reflected by reduced striatal activation during self-reflection compared to during ideal reflection.

Analysis of Rare Variants in the Alcohol Dependence Candidate Gene GATA4

Background

Common variants in the gene GATA binding protein 4 (GATA4) show association with alcohol dependence (AD). The aim of this study was to identify rare variants in GATA4 in order to elucidate the role of this gene in AD susceptibility. Identification of rare variants may provide a more complete picture of the allelic architecture at this risk locus.

Methods

Sanger sequencing of all 6 coding exons of GATA4 was performed in 528 patients and 517 controls. Four in silico prediction tools were used to determine the effect of a DNA variant on the amino acid sequence and protein function. Five variants were included in the replication step. Of these, 4 were successfully genotyped in our replication cohort of 655 patients and 1,501 controls. All patients fulfilled DSM‐IV criteria for AD, and all individuals were of German descent.

Results

In the discovery step, 19 different heterozygous variants were identified. Four patient‐specific and potentially functionally relevant variants were followed up. Only the variant S379S (c.1137C>T) remained patient specific (1/1,166 patients vs. 0/1,997 controls). None of the variants showed a statistically significant association with AD.

Conclusions

The present study elucidated the role of GATA4 in AD susceptibility by identifying rare variants via Sanger sequencing and subsequent replication. Although novel patient‐specific rare variants of GATA4 were identified, none received support in the independent replication step. However, given previous robust findings of association with common variants, GATA4 remains a promising candidate gene for AD.

Real-time functional magnetic resonance imaging neurofeedback can reduce striatal cue-reactivity to alcohol stimuli

It has been shown that in alcoholic patients, alcohol-related cues produce increased activation of reward-related brain regions like the ventral striatum (VS), which has been proposed as neurobiological basis of craving. Modulating this activation might be a promising option in the treatment of alcohol addiction. One approach might be real-time functional magnetic resonance imaging neurofeedback (rtfMRI NF). This study was set up to implement and evaluate a rtfMRI approach in a group of non-addicted heavy social drinkers. Thirty-eight heavy drinking students were assigned to a real feedback group (rFB, n = 13), a yoke feedback group (yFB, n = 13) and a passive control group (noFB, n = 12). After conducting a reward task as functional localizer to identify ventral striatal regions, the participants viewed alcohol cues during three NF training blocks in a 3 T MRI scanner. The rFB group received feedback from their own and the yFB from another participants' VS. The noFB group received no feedback. The rFB and the yFB groups were instructed to downregulate the displayed activation. Activation of the VS and prefrontal control regions was compared between the groups. We found significant downregulation of striatal regions specifically in the rFB group. While the rFB and the yFB groups showed significant activation of prefrontal regions during feedback, this activation was only correlated to the reduction of striatal activation in the rFB group. We conclude that rtfMRI NF is a suitable method to reduce striatal activation to alcohol cues. It might be a promising supplement to the treatment of alcoholic patients.

Memorandum Internetbezogene Störungen der Deutschen Gesellschaft für Suchtforschung und Suchttherapie (DG-Sucht)

Zusammenfassung. Hintergrund: Internetbezogene Störungen stellen noch ein recht junges Phänomen dar. Es besteht die Notwendigkeit auf diese neuen Störungsbilder zu reagieren und Ziele für Behandlung und Versorgung sowie Forschung und Politik zu setzen. Das vorliegende Memorandum fasst den Stand der Erkenntnisse zusammen und formuliert entsprechende Ziele. Methode: In einem iterativen Prozess wurde innerhalb einer Gruppe von 21 Experten ein Konsens erarbeitet. Der finale Text wurde dann noch einmal vom Vorstand der Deutschen Gesellschaft für Suchtforschung und Suchttherapie (DG-Sucht) konsentiert. Ergebnisse: Die Expertengruppe einigt sich auf den Begriff „Internetbezogene Störungen“ und fasst darunter eine ausgeprägte Form, die derzeit am besten bei den Suchterkrankungen verortet werden kann, sowie auch fortgesetzte schädliche oder missbräuchliche Nutzung sowie riskante Nutzungsweisen im Sinne der Vorform einer ausgeprägten Problematik. Es werden Schätzwerte für die Prävalenz sowie Risikofaktoren auf Basis des jetzigen Erkenntnisstands zusammengefasst. Hinsichtlich der Prävention und Behandlung wird resümiert, dass wenig Evidenz zur Verfügung steht. Die Experten leiten dezidierte Ziele und Forderungen für Behandlung, Forschung und politisches Handeln ab. Schlussfolgerung: Das Memorandum weist den jetzigen Kenntnisstand auf, zeigt jedoch auch die vielen eklatanten Lücken. Neben Verbesserungen durch eine vereinheitlichte Diagnostik ist die Entwicklung und insbesondere auch der Wirksamkeitsnachweis für Interventionen in Prävention und Behandlung vordringlich. Ziele der Versorgung sind an zentrale Forschungsfragen gebunden und müssen durch politisches Handeln befördert werden.

The Effect of Nicotine on HPA Axis Activity in Females is Modulated by the FKBP5 Genotype

Tobacco smoking modulates activity in the hypothalamic-pituitary-adrenal (HPA) axis and is used to cope with stress, especially by females. The single nucleotide polymorphism (SNP) rs1360780, linked to FK506-binding protein 51 (FKBP5), has been shown to affect HPA axis functioning, and has thus been suggested as a promising candidate for indicating vulnerability to stress-related disorders. The aim of this study was to investigate the interaction between nicotine consumption and rs1360780 on cortisol plasma levels in females. A total of 296 female smokers (assessed by the Fagerström Test for Nicotine Dependence; FTND) were genotyped for the SNP rs1360780. We measured participants' cortisol plasma concentration in blood plasma collected 3 h after standardized tobacco smoking exposure. In the 36 TT-homozygotes, we found a significant negative correlation between the FTND sum score and cortisol plasma concentrations. Using linear regression analysis, we found that the FTND sum score accounted for 12.4% of the variance of cortisol plasma levels. This association was not detected in C-allele carriers. Our results suggest that nicotine is an important confounder in the modulation of HPA axis activity by FKBP5. In light of these findings, future studies on FKBP5 should seek to include data on nicotine consumption as a covariate.

Association of Common Polymorphisms in the Nicotinic Acetylcholine Receptor Alpha4 Subunit Gene with an Electrophysiological Endophenotype in a Large Population-Based Sample

Variation in genes coding for nicotinic acetylcholine receptor (nAChR) subunits affect cognitive processes and may contribute to the genetic architecture of neuropsychiatric disorders. Single nucleotide polymorphisms (SNPs) in the CHRNA4 gene that codes for the alpha4 subunit of alpha4/beta2-containing receptors have previously been implicated in aspects of (mostly visual) attention and smoking-related behavioral measures. Here we investigated the effects of six synonymous but functional CHRNA4 exon 5 SNPs on the N100 event-related potential (ERP), an electrophysiological endophenotype elicited by a standard auditory oddball. A total of N = 1,705 subjects randomly selected from the general population were studied with electroencephalography (EEG) as part of the German Multicenter Study on nicotine addiction. Two of the six variants, rs1044396 and neighboring rs1044397, were significantly associated with N100 amplitude. This effect was pronounced in females where we also observed an effect on reaction time. Sequencing of the complete exon 5 region in the population sample excluded the existence of additional/functional variants that may be responsible for the observed effects. This is the first large-scale population-based study investigation the effects of CHRNA4 SNPs on brain activity measures related to stimulus processing and attention. Our results provide further evidence that common synonymous CHRNA4 exon 5 SNPs affect cognitive processes and suggest that they also play a role in the auditory system. As N100 amplitude reduction is considered a schizophrenia-related endophenotype the SNPs studied here may also be associated with schizophrenia outcome measures.

The impact of appetite regulating peptides on substance use disorders

Background

Preclinical and clinical data suggest modulating effects of the appetite regulating peptide ghrelin on food intake. Recent data suggest that in food intake the “endostatic” energy-homeostatic systems of the lateral hypothalamus (LH) and the motivational, mesolimbic reward system operate in dynamic interplay with each other. Ghrelin receptors have been detected in the ventral tegmentum of the midbrain (VTA), where they modulate the activity of dopaminergic neurons projecting to the NAc. Assuming that Ghrelin modulate mesolimbic reactivity, the question remains: is this only the case in response to food cues? Or is this the case in response to reward-associated cues in general (including those related to nicotine and alcohol)?

Methods

Study 1: a consecutive sample of 61 alcohol-dependent male inpatients was included. Blood was drawn at onset of withdrawal 12-24 hours after admission, and following 14 days of controlled abstinence in order to assess plasma concentrations of both active and total ghrelin. In parallel, we assessed alcohol craving applying the Obsessive Compulsive Drinking Scale (OCDS) as well as symptoms of depression (Beck Depression Inventory [BDI]) and anxiety (State Trait Anxiety Inventory [STAI]). The severity of alcohol dependence was assessed with the Alcohol Dependence Scale (ADS). Study 2: 54 non-treatment seeking smokers and 30 healthy controls with normal eating behavior, as measured by the Three Factor Eating Questionnaire (TFEQ) participated in this study. We measured plasma concentrations of both active and total ghrelin, using a blood sample taken two hours after a standardized meal during early nicotine abstinence in the smoking group. Additionally we quantified severity of addiction in the smoking group using the number of cigarettes smoked per day, cotinine plasma concentration and the Fagerström Test for Nicotine Dependence (FTND).

Results

Study1: we found a significant positive correlation between the plasma concentration of active ghrelin and alcohol craving in both blood samples. Plasma concentrations of active ghrelin increased significantly during early abstinence. In a linear regression model, the plasma concentration of active ghrelin on day one, the scores of the ADS, and the BDI explained 36% of the variance in OCDS sum score (P < 0001). By day 14, these same factors accounted for 54% (P < 0.0001). We did not detect any association between the plasma concentration of total ghrelin and patients’ alcohol cravings. Study 2: plasma concentration of acetylated ghrelin but not total ghrelin was significantly higher in smokers than in non-smokers. Moreover, we found significant negative correlations between acetylated ghrelin and all measures of the severity of nicotine dependence.

Discussion

In conclusion, both studies supports the general idea that ghrelin's central effects go beyond the endostatic regulation of energy homeostasis, also involving pathways underlying reward expectation and craving. Physiologic factors modulating the reactivity of mesolimbic pathways represent an important research topic for developing pharmacologic treatments for disorders characterized by altered reward-related behaviors, such as substance use disorders and behavioral addictions.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Calcium as a treatment option for alcohol dependence

In the last couple of decades anti-craving drugs have been developed. Acamprosate was described as an effective treatment option to support alcohol abstinence with a low side effect profile. Moreover its molecular mode of action is highly controversial. Recently, calcium salt was described to be the active part of Acamprosate.

Using a clinical sample of placebo (n = 10) vs. Acamprosate-treated (n = 19) abstinent alcohol-dependent patients, we measured calcium plasma concentrations after the 1st, 2nd and 3rd month after the treatment commenced. Before treatment, the same physiological calcium concentration of about 2.4 mmol/l was found in both groups respectively. We found significant correlations in the Acamprosate group while no correlations in the placebo group were observed.

The very well regulated extracellular calcium serum concentration seems to get out of balance in association with the severity of alcohol dependence in inpatients during withdrawal.

Accordingly, in another clinical sample (n = 57) we found a negative correlation between calcium serum concentration and craving (r2= 0.125; P = 0.011) on day 1 of detoxification. The measurement of craving was carried out by a self-rating scale, the Obsessive Compulsive Drinking Scale (OCDS). Furthermore a low calcium level correlated with high breathalyser readings and the number of alcohol inpatient detoxification's.

Disclosure of interest

The authors have not supplied their declaration of competing interest.