Attention-deficit/hyperactivity disorder: cognitive evoked potential (P300) amplitude predicts treatment response to atomoxetine

Objective Auditory cognitive evoked potential (P300) topography was reported to predict robust response to the stimulants pemoline and extended-release methylphenidate in patients with attention-deficit/hyperactivity disorder (ADHD). Patients with a right fronto-central to parietal auditory P300 amplitude ratio >0.5 respond robustly to stimulants, others do not. This exploratory study was performed to demonstrate whether the P300 predicts treatment response to the selective norepinephrine re-uptake inhibitor, atomoxetine. Methods Patients aged 6–17 with DSM-IV diagnosis of ADHD were administered P300 testing. They then underwent open-label treatment with atomoxetine. Robust response was defined as a 60% decrease from baseline in the ADHD rating scale (parent version, investigator rated). Results Ten of 17 subjects responded robustly. They did not differ from the non-robust responders in age, baseline attention or hyperactivity ratings, or any P300 parameter except 31-electrode mean auditory P300 amplitude (mean AA). Mean AA >6.8 μV predicted robust response with positive predictive value of 0.88 and negative predictive value of 0.67. Conclusions Mean AA seems to predict response to atomoxetine in patients with ADHD. Significance As non-stimulant treatments are approved for the treatment of ADHD, tests such as this may help pinpoint whether to use a stimulant or a medicine with some other mechanism of action.