Impulsiveness as the intermediate link between the dopamine receptor D2 gene and alcohol dependence

Objectives Reinforcement and reward processes have been proposed as being an intermediate link between the risk for alcohol dependence and the gene coding for the dopamine receptor D2 (DRD2). This hypothesis remains open to speculation, and personality traits such as impulsiveness, a core dimension in addictive disorders, should also be taken into account. For instance, recent evidence in rats showed that DRD2 antagonists might increase impulsivity in decreasing the value of delayed rewards. Methods Considering the pro-impulsiveness role of ethanol observed in clinical practice and epidemiological studies, we analysed the Barratt impulsiveness scores in a sample of 92 alcohol-dependent French patients (57 men and 35 women), according to the Taql A polymorphism of the DRD2 gene. Results A2/A2 and A1/A2 genotypes were significantly associated with a higher global impulsiveness than A1/A1 genotype (P=0.02 and P=0.03, respectively). Conclusions We propose that reward-related impulsiveness may constitute a risk factor for alcohol dependence, and that this core temperament could be partly mediated by the DRD2 gene. (C) 2003 Lippincott Williams Wilkins.