Effects of gender and family history of alcohol dependence on a behavioral task of impulsivity in healthy subjects.

OBJECTIVE: Substance misusers are often considered impulsive, but it is unclear whether impulsivity precedes substance misuse or develops as a consequence of it. Because alcohol dependence has a clear familial component, a study comparing impulsivity in nonaffected individuals who differ with respect to paternal history of alcohol dependence may provide evidence of familial vulnerability to impulsivity.
METHOD: 122 healthy individuals participated, none of whom misused alcohol or drugs; 58 were paternal history positive (PHP) and 64 were paternal history negative (PHN) for alcohol dependence. The paternal-history groups were balanced on gender, and the four paternal-history-by-gender groups were comparable with respect to demographic features. Participants were offered choices between monetary rewards (e.g., $34) available immediately and larger rewards (e.g., $50) available after delays ranging from 1 week to 6 months. This task measures a construct of impulsivity by assessing the rates at which individuals discount rewards delayed in time.
RESULTS: Although discount rates in PHP men did not differ reliably from those in PHN men, PHP women had higher discount rates than PHN women. Post hoc contrasts revealed that PHN women had lower discount rates than the other three groups. Similar results were obtained when age, education, socioeconomic status, and scores on a measure of sociopathy were used as covariates.
CONCLUSIONS: Paternal history of alcohol dependence is associated with greater discount rates among women. The lack of an effect for men may suggest different mechanisms by which risk is transmitted from alcohol-dependent fathers to daughters compared with sons. Further research examining these relations and the implications that delay discounting has for drinking and related behaviors is warranted.