Abstract
RATIONALE: Impulsive behavior is associated with both alcohol use disorders and a family history of alcoholism (FHA). One operational definition of impulsive behavior is the stop-signal task (SST) which measures the time needed to stop a ballistic hand movement. OBJECTIVE: Employ functional magnetic resonance imaging (fMRI) to study right frontal responses to stop signals in heavy drinking subjects with and without FHA, and as a function of alcohol exposure. METHODS: Twenty-two family history-positive (FHP; age = 22.7 years, SD = 1.9) and 18 family history-negative (FHN; age = 23.7, SD = 1.8) subjects performed the SST in fMRI in two randomized visits: once during intravenous infusion of alcohol, clamped at a steady-state breath alcohol (BrAC) concentration of 60 mg/dL, and once during infusion of placebo saline. An independent reference group (n = 13, age = 23.7, SD = 1.8) was used to identify a priori right prefrontal regions activated by successful inhibition (Inh) trials, relative to "Go" trials that carried no need for inhibition [Inh > Go]. RESULTS: FHA interacted with alcohol exposure in right prefrontal cortex, where alcohol reduced [Inh > Go] activation in FHN subjects but not in FHP subjects. Within this right frontal cortical region, stop-signal reaction time also correlated negatively with [Inh > Go] activation, suggesting that the [Inh > Go] activity was related to inhibitory behavior. CONCLUSIONS: The results are consistent with the low level of response theory (Schuckit, J Stud Alcohol 55:149-158, 1980; Quinn and Fromme, Alcohol Clin Exp Res 35:1759-1770, 2011), with FHP being less sensitive to alcohol's effects.