Irene Guerrini

The Evolution and Treatment of Korsakoff's Syndrome

Wernicke’s Encephalopathy is an acute neuro-psychiatric condition caused by an insufficient supply of thiamine (Vitamin B1) to the brain. If undiagnosed or inadequately treated, it is likely to proceed to Korsakoff’s Syndrome. Wernicke’s Encephalopathy can result from dietary deficiency alone and this form is usually successfully treated, with little chance of Korsakoff’s Syndrome supervening. On the other hand, thiamine deficiency associated with alcohol misuse/dependence may require up to 1 gram of thiamine IV in the first 24 hours to be treated successfully. The reasons for this difference in treatment will be discussed. Thiamine diphosphate acts as a co-factor for a number of thiamine-dependent enzymes. Thiamine deficiency leads to a reduction in the activity of these enzymes, and this leads to alterations in mitochondrial activity, impairment of oxidative metabolism, decreased energy status and eventually selective neuronal death. The damage caused by the combination of thiamine deficiency and alcohol metabolism probably interferes with adequate thiamine transport at a number of sites in the body, including the blood–brain barrier, as well as causing damage to the apoenzymes which then require higher concentrations of thiamine to work normally. The accumulated damage is likely to render the use of oral thiamine therapeutically inadequate since the body is unable to produce high enough concentrations of thiamine in the blood to traverse the blood–brain barrier. Some individuals are probably genetically predisposed to develop Wernicke’s. Long before individuals with alcohol misuse or dependence develop Wernicke’s Encephalopathy the neurons and other cells of the body are functioning sub-optimally because of the inadequate supply of thiamine and the neurotoxic effect of alcohol. This relative deficiency initiates a series of pathological changes which accumulate and further interfere with the supply of thiamine and its utilisation at a time when the requirements are increased. The best treatment for Korsakoff’s Syndrome is timely recognition of Wernicke’s Encephalopathy and appropriate intervention and prevention.

Genetic linkage analysis supports the presence of two susceptibility loci for alcoholism and heavy drinking on chromosome 1p22.1-11.2 and 1q21.3-24.2

BackgroundIn order to confirm a previous finding of linkage to alcoholism on chromosome 1 we have carried out a genetic linkage study.MethodsDNA from eighteen families, densely affected by alcoholism, was used to genotype a set of polymorphic microsatellite markers at loci approximately 10 centimorgans apart spanning the short arm and part of the long arm of chromosome 1. Linkage analyses were performed using the classical lod score and a model-free method. Three different definitions of affection status were defined, these were 1. Heavy Drinking (HD) where affected subjects drank more than the Royal College of Psychiatrists recommended weekly amount. 2. The Research Diagnostic Criteria for alcoholism (RDCA) 3. Alcohol Dependence Syndrome (ADS) as defined by Edwards and Gross (1976) and now incorporated into ICD10 and DSMIV.ResultsLinkage analyses with the markers D1S1588, D1S2134, D1S1675 covering the cytogenetic region 1p22.1-11.2 all gave positive two point and multipoint lods with a maximum lod of 1.8 at D1S1588 (1p22.1) for the RDCA definition of alcoholism. Another lod of 1.8 was found with D1S1653 in the region 1q21.3-24.2 using the HD affection model.ConclusionThese results both support the presence of linkage in the 1p22.1-11.2 region which was previously implicated by the USA Collaborative Study of the Genetics of Alcoholism (COGA) study and also suggest the presence of another susceptibility locus at 1q21.3-24.2.

Molecular genetics of alcohol-related brain damage.

AIMS In the scientific literature it has been repeatedly hypothesized that there is a heritable susceptibility to thiamine deficiency comparable to other hereditary metabolic disorders. The aim of this paper is to review the most recent knowledge on the genetic susceptibility to the development of alcohol-related Wernicke-Korsakoff syndrome (WKS). METHODS A literature review was carried out looking at the molecular genetics studies performed in alcohol-dependent patients affected by WKS. RESULTS A genetic component in the pathogenesis of WKS has been postulated since the late seventies. Since then, very few genetic studies have been carried out on candidate genes such as thiamine-dependent enzymes, alcohol-metabolizing enzymes and GABA receptors. The findings are controversial and not conclusive. Several authors reported the important role of the thiamine transporters in the pathogenesis of the thiamine deficiency disorders. Our findings on SLC19A2 and SLC19A3 suggest a potential role of these two genes in the pathophysiology of alcohol-related thiamine deficiency but further studies need to be carried out. CONCLUSIONS The WKS may be a very complex, multifactorial disorder where the interaction of multiple genes and environment plays an important role in the pathogenesis. However, it is still plausible that megaphenic gene effects are responsible for WKS susceptibility and the thiamine transport genes are good candidates for having such a role. Further genetic studies are definitely needed to investigate the association with candidate genes or linkage with hot spot areas.

Confirmation of prior evidence of genetic susceptibility to alcoholism in a genome-wide association study of comorbid alcoholism and bipolar disorder.

Objectives Alcoholism and affective disorders are both strongly comorbid and heritable. We have investigated the genetic comorbidity between bipolar affective disorder and alcoholism. Methods A genome-wide allelic association study of 506 patients from the University College London bipolar disorder case–control sample and 510 ancestrally matched supernormal controls. One hundred forty-three of the bipolar patients fulfilled the Research Diagnostic Criteria diagnosis of alcoholism. A total of 372 193 single nucleotide polymorphisms (SNPs) were genotyped. Genes previously shown to be associated with alcoholism and addiction phenotypes were then tested for association in the bipolar alcoholic sample using gene-wise permutation tests of all SNPs genotyped within a 50-kb region flanking each gene. Results Several central nervous system genes showed significant (P<0.05) gene-wise evidence of association with bipolar alcoholism. The genes implicated, which replicated genes previously shown to be associated with alcoholism were: cadherin 11, collagen type 11 &agr;2, neuromedin U receptor 2, exportin7, and semaphorin-associated protein 5A. The SNPs most strongly implicated in bipolar alcoholism, but, which did not meet conventional genome-wide significance criteria were the insulin-like growth factor-binding protein 7, carboxypeptidase O, cerebellin 2, and the cadherin 12 genes. Conclusion We have confirmed the role of some genes previously shown to be associated with alcoholism in the comorbid bipolar alcoholism subgroup. In this subgroup, bipolar disorder may lower the threshold for the phenotypic expression of these alcoholism susceptibility genes. We also show that some genes may independently increase susceptibility to affective disorder and alcoholism.

Mutations in the Gabrb1 gene promote alcohol consumption through increased tonic inhibition

Alcohol-dependence is a common, complex and debilitating disorder with genetic and environmental influences. Here we show that alcohol consumption increases following mutations to the γ-aminobutyric acidA receptor (GABAAR) β1 subunit gene (Gabrb1). Using N-ethyl-N-nitrosourea mutagenesis on an alcohol-averse background (F1 BALB/cAnN × C3H/HeH), we develop a mouse model exhibiting strong heritable preference for ethanol resulting from a dominant mutation (L285R) in Gabrb1. The mutation causes spontaneous GABA ion channel opening and increases GABA sensitivity of recombinant GABAARs, coupled to increased tonic currents in the nucleus accumbens, a region long-associated with alcohol reward. Mutant mice work harder to obtain ethanol, and are more sensitive to alcohol intoxication. Another spontaneous mutation (P228H) in Gabrb1 also causes high ethanol consumption accompanied by spontaneous GABA ion channel opening and increased accumbal tonic current. Our results provide a new and important link between GABAAR function and increased alcohol consumption that could underlie some forms of alcohol abuse.

Genetic association study of GABRA2 single nucleotide polymorphisms and electroencephalography in alcohol dependence

The gamma aminobutyric acid (GABA) system has been implicated in the susceptibility to develop alcohol dependence and in determining electroencephalogram (EEG) beta activity. The role of the GABA receptor alpha-2 gene (GABRA2) in human alcohol dependence was determined in a genetic and electrophysiological study. The study population comprised 586 white UK individuals with alcohol dependence but a very low prevalence of co-morbid drug dependence, and 603 ancestrally matched healthy controls. Genotyping for seven GABRA2 single nucleotide polymorphisms (SNPs), identified from the literature as positively associated with alcohol dependence, was performed with success rates of 90% or greater. EEGs were available in 32 selected patients who had been abstinent from alcohol for a minimum of 24 months and in 138 ancestrally matched healthy controls. None of the SNPs showed allelic or haplotypic association with alcohol dependence. All markers were in Hardy Weinberg equilibrium (HWE) in the controls. HWE for marker rs279841 in the alcohol dependent sample was p=0.0199 and combined p=0.0166. Linkage disequilibrium patterns appear to be very similar to that observed in the HapMap CEU data. A significantly higher prevalence of excess EEG fast activity was found in the patients (31 vs. 14%, p=0.018). A significant relationship was found between the presence of excess EEG fast activity and GABRA2 SNPs rs548583, rs279871 and rs279841. This allelic association study provides no evidence for an association between GABRA2 polymorphisms and alcohol dependence. However, a significant relationship was identified between GABRA2 and excess EEG fast activity. This dissociation of effect may reflect the fact that the EEG is a more direct marker of phenotypic GABRA2 expression than the more heterogeneous alcohol dependence phenotype.

Direct genomic PCR sequencing of the high affinity thiamine transporter (SLC19A2) gene identifies three genetic variants in Wernicke Korsakoff Syndrome (WKS)

Irene Guerrini, Allan D. Thomson, Cristopher C.H. Cook, Andrew McQuillin, Vishal Sharma, Michael Kopelman, Gerald Reynolds, Pramod Jauhar, Clive Harper, and Hugh M.D. Gurling* Molecular Psychiatry Laboratory, Windeyer Institute of Medical Sciences, Department of Mental Health Sciences, Royal Free and University College London Medical School, London, United Kingdom Kent Institute of Medicine and Health Science, University of Kent at Canterbury, United Kingdom St. Chad’s College, Durham, United Kingdom Neuropsychiatry and Memory Disorders Clinic, University Department of Psychiatry and Psychology, King’s College, St. Thomas’s Campus, London, United Kingdom Parkhead Hospital, Greater Glasgow Primary Care Trust and Department of Psychological Medicine, University of Glasgow, United Kingdom Neuropathology Department, University of Sydney and Sydney South West Area Health Service, New South Wales, Australia

Alcohol-related brain damage: report from a Medical Council on Alcohol Symposium, June 2010

### Alcohol-Related Brain Damage: Challenges and Opportunities Colin Drummond National Addiction Centre, Institute of Psychiatry, Kings College London, UK Alcohol is a toxic and dependence-producing substance that can damage most organs in the body, and is implicated in more than 60 different diseases (Oforei-Adjei et al. , 2007). Alcohol is now the third leading cause of ill health in Europe (Rehm et al. , 2009). In the UK, alcohol-related morbidity and mortality have been increasing over the last 30 years, and alcohol-related hospital admissions now exceed 1 million per annum in England (North West Public Health Observatory, 2011). The brain is particularly sensitive to the toxic effects of alcohol either directly, particularly in the foetus and young people, or in the context of malnutrition and thiamine deficiency leading to Wernicke–Korsakoff syndrome; or following repeated episodes of alcohol withdrawal. The precise mechanisms of alcohol-related brain damage (ARBD) remain to be fully understood and several papers in this series describe the limits of knowledge. However, enough is already known to make a significant impact on the prevalence of ARBD through relatively inexpensive preventive strategies. Yet, such preventive strategies are poorly implemented in the UK. Why is this the case? First, there has been a lack of training and clear guidance to clinicians on preventing and managing alcohol problems, including ARBD. This has resulted in low levels of identification and intervention of patients at risk of alcohol-related complications in medical and psychiatric care (Barnaby et al. , 2003; Cheeta et al. , 2008). The recently published suite of NICE guidance on alcohol-use disorders aims to improve detection, prevention and management (NICE, 2010a, b, 2011). However, effective implementation will require a significant investment in staff training to raise awareness, knowledge and skills. Secondly, there is the issue of stigma. Patients who misuse alcohol face stigma and opprobrium, …

The functional GRM3 Kozak sequence variant rs148754219 affects the risk of schizophrenia and alcohol dependence as well as bipolar disorder

We previously reported that a Kozak sequence variant in the metabotropic glutamate receptor 3 gene (GRM3), rs148754219, is associated with bipolar disorder (BP) and affects gene transcription and translation (Kandaswamy et al., 2013). A marker near GRM3, rs12704290, is one of the top hits and reached genome-wide significance in a recently reported genome-wide association study of schizophrenia (SZ) (Ripke et al., 2014), and markers for GRM3 have also been reported to demonstrate association with alcohol dependence syndrome (ADS) (Levey et al., 2014). In our original sample, considering patients successfully genotyped for rs148754219, 19 out of 1062 BP cases and only four out of 932 controls were heterozygous [odds ratio (OR)=4.2 (1.4–12.3), P=0.005]. We have genotyped this variant in additional controls and cases diagnosed with BP, SZ and ADS with the same ancestry. Patients were assessed by trained clinicians as described previously (Kandaswamy et al., 2013; Way et al., 2014). Allele counts were compared and significance was tested using Fisher’s exact test. Thirteen out of 934 additional BP cases and three out of 377 additional controls were heterozygous [OR=1.8 (0.49–6.2), P=not significant]. Combined with the originally reported results (Kandaswamy et al., 2013), 32 out of 1964 BP cases and seven out of 1309 controls were heterozygous [OR=3.0 (1.3–6.8), P=0.003]. Out of 1235 SZ cases 16 were heterozygous and were compared with the total control sample [OR=2.4 (0.99–5.8), P=0.03]. Out of 1514 ADS cases 18 were heterozygous and one was homozygous for the variant allele [OR=2.5 (1.0–5.9), P=0.03]. If all case cohorts (BP, SZ and ADS) are combined together, there would be one homozygote and 66 heterozygotes out of 4971 cases compared with the seven heterozygotes out of 1309 controls [OR=2.7 (1.2–5.8), P=0.004]. Previous work has supported the view that some genetic risk factors may be common to different psychiatric diagnoses (Lydall et al., 2011; Lee et al., 2013). Although the individual results are of questionable significance, the magnitude and direction of effect are consistent across all the cohorts and thus suggest the possibility that this rare variant may have a direct, functional effect on the risk of developing any of these three disorders. Because of its rarity, large sample sizes would be needed to confirm these results. Doing this would be worthwhile because if this finding is confirmed it could provide molecular insight into a mechanism involving GRM3 leading to increased risk of mental disorders and could provide a basis for further functional and therapeutic studies.

Biomarkers for Detecting Thiamine Deficiency—Improving Confidence and Taking a Comprehensive History are also Important

We were very interested to read this letter in the recent issue of Alcohol & Alcoholism written in response to the paper by Mancinelli and Ceccanti (2009). We agree with the authors that the use of biomarkers complements the taking of a comprehensive history. The authors mentioned the measurement of erythrocyte transketolase activity, which has been used for many years as a measure of thiamine deficiency. However, this test is not usually routinely available in clinical practice or on an emergency basis in most UK hospitals, and there is debate about …