Examining the association between stimulant treatment and cognitive outcomes across the life cycle of adults with attention-deficit/hyperactivity disorder: A controlled cross-sectional study

Few studies have evaluated the effects of stimulants on cognition in adults with attention-deficit/hyperactivity disorder (ADHD). We evaluated the impact of stimulant treatment on neurocognition in a cross-sectional sample of adults with ADHD. Comparisons were made between adults with ADHD who received (n = 105) and who had never received pharmacotherapy (n = 116) and 146 controls. The subjects were assessed cross-sectionally using a structured diagnostic interview and a neurocognitive battery. We modeled cognitive measures as a function of age and group status using linear regression. Treated ADHD subjects had statistically significantly better scores on measures of IQ than did untreated ones. The treated group also had better (not statistically significant) scores on neuropsychological measures. The direction of the effects of stimulant on neurocognition suggests that either good cognitive functioning may be a determinant of seeking treatment or that stimulant treatment may improve cognition in adults with ADHD. However, this does not indicate a clear causal relationship.