Impulsivity has been identified as a behavioral precursor to addiction, and may be the manifestation of a neurological vulnerability. The present study investigated whether individual differences in impulsivity were associated with performance on the Iowa Gambling Task (IGT, a test of emotional decision making thought to be associated in part with ventromedial prefrontal cortex function) and the Wisconsin Card Sorting Task (WCST, a set-shifting thought to be associated in part with dorsolateral prefrontal cortex function). Subjects were screened for impulsivity using the BIS-11 (self-report) and a delay discounting questionnaire (a behavioral measure of impulsivity). High impulsivity was associated with poorer performance on the final block of trials of the IGT but was not significantly related to WCST performance. Both measures were significantly correlated with scores on the BIS. These results provide support for hypothesis that, in a nonclinical sample, impulsivity may vary systematically with performance on neuropsychological indicators of prefrontal function. (JINS, 2008, 14, 878–882.)

Risk taking in a large cohort of adults (N = 177; ages 17–73) decreased with age, demonstrated by performance on a computer based gambling task, which has previously been shown to be sensitive to certain pharmacological manipulations including tryptophan depletion, lesions of the orbitofrontal cortex and neuropsychiatric disorders such as mania. Aging was also associated with longer deliberation times, poorer decision making, reduced risk taking, but no significant change in delay aversion. Subjects with a higher (NART-estimated) IQ were faster to make decisions and showed a greater modulation of risk-taking. Both sexes showed similar patterns of decision making, although male participants exhibited a greater modulation of risk-taking in response to the probability of winning. The Decision-Gamble task provides a variety of behavioral measures, corresponding to different aspects of impulsivity. Factor analysis of these measures suggested that two independent traits underlies performance on the task in normal individuals: one associated with risk tolerance, and a second associated with delay aversion. Age was related to decreases in the risk tolerance factor, but unrelated to the delay aversion; neither factor was significantly related to verbal IQ. This study thus provides support for the concept that impulsivity can be fractionated into 2 or more components. (JINS, 2004, 10, 590–598.)