P3 event-related potential, dopamine D2 receptor A1 allele, and sensation-seeking in adult children of alcoholics.

BACKGROUND: Research has indicated a close relationship between the P3 event-related potential and the dopamine D2 receptor A1 allele in individuals at high risk for alcoholism. Other research has suggested an association between the dopamine D2 receptor A1 allele and sensation-seeking. In this study, we further examined the relationships between the P3, the A1 allele, and sensation-seeking in a sample of nonalcoholic adult children of alcoholics. METHODS: Participants (n = 57; range, 19-30 years; 41 women), who performed a visual novelty oddball task to elicit the P3, were asked to fill in personality questionnaires, including Zuckerman's Sensation-Seeking Scale, and were classified according to the presence of the dopamine D2 receptor A1 allele. The effects of sex, age, and socioeconomic status were assessed to determine whether these variables affected the relations between the P3, the A1 allele, and sensation-seeking. RESULTS: A small P3 amplitude was associated with high sensation-seeking, particularly with high disinhibition. The presence of the A1 allele was also associated with high disinhibition, but only in men. By contrast, P3 amplitudes and latencies were not associated with the presence of the A1 allele. CONCLUSIONS: Although a small P3 amplitude, high sensation-seeking, and the presence of the A1 allele were all associated with alcoholism risk, these findings indicate that these three characteristics together do not reflect a common risk factor in alcoholism.

Platelet adenylyl cyclase activity as a biochemical trait marker for predisposition to alcoholism.

Previous studies demonstrated a reduced Gs-protein stimulated adenylyl cyclase activity in the brain and blood cells of alcoholics. We investigated this phenomenon in platelets of children of alcoholics (COA), i.e., of children at high risk for the acquisition of alcoholism and (as yet) not regularly consuming alcohol. Gs-protein mediated stimulation of adenylyl cyclase by 30 mM NaF and 50 microM forskolin stimulated adenylyl cyclase activity were assessed in platelet membranes of 23 (male and female) COA and 20 control children. Gs-protein stimulated cAMP production by NaF, unlike that induced by direct stimulation of adenylyl cyclase with forskolin, in platelet membranes of COA was profoundly lower than in platelet membranes of control children. Moreover, such a reduced Gs-protein functioning was only observed in platelet membranes of COA with a multigenerational family history of alcoholism. A reduction of Gs-protein stimulated adenylyl cyclase activity in platelets may represent a sensitive and gender-independent trait marker for predisposition to alcoholism, rather than a state marker for alcoholism.