Atomoxetine and adult attention-deficit/hyperactivity disorder: The effects of comorbidity

Objective: The objective of this study was to determine if measures of broad clinical psychopathology or neuropsychological performance could aid in the prediction of therapeutic response to the highly selective norepinephrine transporter inhibitor, atomoxetine, among adults with attention-deficit/hyperactivity disorder (ADHD). Method: We analyzed data from 2 double-blind, placebo-controlled, parallel design studies of adult patients (Study I, N = 280; Study II, N = 256) with DSM-IV-defined ADHD who were recruited by referral and advertising. Subjects were randomly assigned to 10 weeks of treatment with atomoxetine or placebo and were assessed with Conners' Adult ADHD Rating Scales (CAARS), the General Well-Being Schedule (GWB), the Sheehan Disability Scale, the Stroop Color-Word Test (SCWT), and the Structured Clinical Interview for DSM-IV (SCID) before and after treatment. Results: Therapeutic improvement on atomoxetine as evidenced by reduced CAARS scores was reliably predicted by the presence of a lifetime comorbid diagnosis of depression or post-traumatic stress disorder at baseline, while improvement oil subscales of the GWB and Sheehan Disability Scale were predicted by these and other SCID endorsements, such as alcohol and substance use, as well as demographics such as age and gender. In light of the exploratory nature of this work and the many comparisons that were examined in the corresponding regression models, these findings should be regarded as tentative pending replication and extension in another dataset. Conclusion: From these findings, we conclude that the variable responsiveness of individuals to atomoxetine cannot be largely accounted for by differences in broad-spectrum psychopathology or neuropsychological indicators of attentional capacity.