| Delay and probability discounting tasks are well-established behavioral measures for determining impulsivity and risk-taking, respectively. Stimulant medications have been found to be efficacious overall in treating the symptoms of attention-deficit/ hyperactivity disorder (ADHD); however, few studies have examined their effects on specific symptoms, such as impulsivity and risk-taking behavior. Utilizing discounting measures to examine the impact of stimulant medication on impulsivity and risk-taking in individuals with ADHD may provide new and important information. This study examined the effects of stimulant medication on these specific symptomatic problems in adults with ADHD using delay and probability discounting tasks.;Fifty participants, 25 with ADHD and 25 matched controls, were compared using delay and probability discounting functions. Participants with ADHD were tested on two separate occasions, while "on" and "off" their medication, to examine the effect of stimulant medication on these tasks compared to participants without ADHD. The discounting functions were analyzed using the "area under the curve" method described by Myerson, Green, and Warusawitharana because it was theoretically neutral and commonly used in the discounting literature. Steeper discounting indicated more impulsivity on the delay curve, whereas shallower discounting indicated more risk-taking on the probability curve.;Results showed that adults with ADHD only discounted delayed rewards slightly more steeply, were only slightly more impulsive, than adults without ADHD; however, there was no difference for the discounting functions of adults with and without ADHD for probability discounting. There were no significant differences between the delay discounting functions of adults with ADHD on versus off medication, but this may be due to the small sample size as the trend was toward indications of less impulsive responding when individuals were taking their stimulant medication. In general, the findings suggest that individuals with ADHD may be more impulsive, but not necessarily more inclined to engage in risk-taking behavior, than matched control peers. Stimulant medication is possibly beneficial in decreasing impulsivity in adults with ADHD; however, it does not seem to impact risk-taking behavior. (116 pages). |
