Heterogeneity in early onset alcoholism suggests a third group of alcoholics

Review. Genetics of addictions: strategies for addressing heterogeneity and polygenicity of substance use disorders

Addictions are common psychiatric disorders that exert high cost to the individual and to society. Addictions are a result of the interplay of multiple genetic and environmental factors. They are characterized by phenotypic and genetic heterogeneity as well as polygenicity, implying a contribution of different neurobiological mechanisms to the clinical diagnosis. Therefore, treatments for most substance use disorders are often only partially effective, with a substantial proportion of patients failing to respond. To address heterogeneity and polygenicity, strategies have been developed to identify more homogeneous subgroups of patients and to characterize genes contributing to their phenotype. These include genetic linkage and association studies as well as functional genetic analysis using endophenotypes and animal behavioural experimentation. Applying these strategies in a translational context aims at improving therapeutic response by the identification of subgroups of addiction patients for individualized, targeted treatment strategies. This article aims to discuss strategies addressing heterogeneity and polygenicity of substance use disorders by presenting results of recent research on genetic and environmental components of addiction. It will also introduce the European IMAGEN study that aims to integrate methodical approaches discussed in order to identify the genetic and neurobiological basis of behavioural traits relevant to the development of addictions.

Tobacco smoking and the ADRA2A C-1291G polymorphism

The aim of the present study is to test for possible associations between the C-1291G polymorphism in the alpha2A-adrenergic receptor gene (ADRA2A) with tobacco smoking and alcohol dependence. The genotype and allele frequencies were compared in three groups of European-derived Brazilian males: individuals with co-occurrence of tobacco smoking and alcohol dependence (N = 110), with tobacco smoking (N = 121) and controls (N = 114). The frequency of the G allele was higher in the group with both conditions, intermediate among subjects with smoking, and lower among controls (chi(2) = 8.00; p = 0.02). The chi(2) partitioning did not reveal significant differences between the sample with the two conditions and the sample of smokers (chi(2) = 0.82; p = 0.36). Combining both groups, the difference to the non-smoking controls is higher than the one observed in the three-groups analysis (chi(2) = 7.18; p = 0.007). The results suggest a role for the ADRA2A C-1291G polymorphism, notably the G allele, in the predisposition to tobacco smoking. The influence of the ADRA2A gene in nicotine and other substance dependencies should be more extensively assessed in future studies.

The use of legal coercion in the treatment of substance abusers: an overview and critical analysis of thirty years of research

Drug and alcohol use presents a serious social problem for most countries in the world. Of particular concern is the well-documented relationship between substance use and crime, which has contributed to an increased popularity and willingness to utilize more forceful means to pressure substance users into treatment. Although compulsory/legally mandated treatment is appealing, it has been one of the most fiercely debated topics in the addiction field, raising a number of issues including ethical concerns and motivational considerations. In this context, the most important question to be answered is whether or not compulsory treatment is effective in the rehabilitation of addicted offenders. Regrettably, three decades of research into the effectiveness of compulsory treatment have yielded a mixed, inconsistent, and inconclusive pattern of results, calling into question the evidence-based claims made by numerous researchers that compulsory treatment is effective in the rehabilitation of substance users. The present paper provides an overview of the key issues concerning the use and efficacy of legal coercion in the rehabilitation of substance users, including a critique of the research base and recommendations for future research.

Examination of type I/type II alcoholism typology in a Greek hospital treatment population

OBJECTIVE

The study aims at testing the validity of two types of classification of male alcoholism in a Greek hospital treatment sample.

METHOD

The study population was drawn from male patients with alcohol dependence admitted to the Alcohol Treatment Unit of the Psychiatric Hospital of Attica. Seventy-three patients comprised the study sample after exclusion of subjects with alcohol dependence suffering from a comorbid serious medical condition, schizophrenic disorder, bipolar disorder, drug dependence or abuse, organic mental disorder or inability to read. The alcoholics were grouped in type I and II adopting the criterion of age-of-onset used by von Knorring et al. (1985). Impulsivity, suicide risk and violence risk were measured by means of the impulse control scale (ICS), the suicide risk scale (SRS) and the past feelings and acts of violence scale (PFAVS).

RESULTS

Fifty patients with alcohol dependence were defined as late-onset and 23 as early-onset. Compared to late-onset patients, early-onset individuals with alcohol dependence had more familial alcoholism (P = 0.032); they were in a higher rate unmarried (P = 0.001), had no stable job before entry in the Unit (P = 0.007) and scored higher on ICS (P = 0.046) and SRS (P = 0.024).

CONCLUSION

The present study confirms type I/type II dichotomy of male alcoholism and also shows that the age-of-onset is a valid classification criterion.

Estado atual e perspectivas da genética e epidemiologia do alcoolismo

O alcoolismo é um problema de saúde pública de escala mundial. O abuso e dependência combinados afetam aproximadamente 8% da população brasileira, gerando um grande custo social. O reconhecimento da existência de uma herdabilidade significativa contribuiu para o entendimento do problema como uma doença específica com origem biológica. Os avanços no conhecimento da neurobiologia da dependência permitiram delimitar uma série de genes candidatos para a predisposição. Atualmente, iniciam-se os estudos sobre o papel de polimorfismos genéticos na resposta ao tratamento. A integração de abordagens clínicas, epidemiológicas e de genética molecular pode identificar grupos clínicos mais responsivos a abordagens terapêuticas específicas.