Nicotine Effects on Attention: Implications for ADHD Therapy

A self-medication theoiy of substance abuse has been proposed to account for high prevalence of cigarette smoking in adults with attention-deficit hyperactivity disorder (ADHD). It has been suggested that in smokers with ADHD nicotine might attenuate some of the symptoms of the disorder, especially inattentiveness. Animal research and human studies using non-ADHD smokers and non-smokers have produced mixed evidence on the cognitive effects of nicotine with the most consistent finding of improved sustained attention in a variety of vigilance tasks. Few existing studies examining the effects of nicotine in ADHD adults have provided further support to the hypothesis of ameliorating effects of nicotine on sustained attention. The present study was conducted to evaluate whether adult non-smokers with low attentiveness might exhibit greater sensitivity to nicotine and consequently greater improvement on measures of attention and working memory than those with higher attentiveness using neuropsychological tests that had previously shown usefulness in the diagnosis of ADHD.In accordance with their attention scores on the Current Symptoms Scale by Barkley and Murphy and Self-Report Rating Scale by McCamey and Anderson, 62 male non-smokers were assigned to either low (possible problems of inattentiveness) or high (few or no attentional difficulties) attention groups. Each participant was treated with either a placebo or a 7mg- of- nicotine transdermal patches. Six hours after the application of a patch, participants were individually administered the Wisconsin Card Sorting Test, classic Stroop task, and Conner's Continuous Performance Test (CPT) in a counterbalanced order. The results did not show performance differences on the Stroop task. On the Conner's CPT nicotine reduced the number of errors of commission, improved stimulus detectability and reduced the number of perseverations irrespective of the attentional group status. On the Wisconsin Card Sorting test nicotine significantly impaired the ability of non-smokers in the high attention group to learn effective strategies to complete the test with fewer trials. The results suggested nicotine-induced improvement on some measures of sustained attention. Overall, the study did not produce conclusive evidence of cognitive effects of nicotine possibly due to the lack of tolerance in non-smokers to the adverse physiological effects of nicotine.