Improvement of executive functions in boys with attention deficit hyperactivity disorder: an open-label follow-up study with once-daily atomoxetine.
Atomoxetine is efficacious in reducing symptoms of attention deficit hyperactivity disorder (ADHD) but its effect on executive functions needs more investigation. We examined the effect of atomoxetine on a wide range of non-verbal executive functions among 30 drug-naive male patients with DSM-IV ADHD, aged 8-16 yr, in an open-label 12-wk atomoxetine treatment trial. Before administration of atomoxetine, the participants were assessed by psychiatric interviews, the WISC-III, and the tasks involving executive functions of the Cambridge Neuropsychological Test Automated Battery (CANTAB): Intra-dimensional/Extra-dimensional Shifts (IED), Rapid Visual Information Processing (RVIP), Spatial Span (SSP), Spatial Working Memory (SWM), and Stockings of Cambridge (SOC); and reassessed at weeks 4 and 12. All the raw scores of the CANTAB were transformed to z scores based on a normative sample of 180 children aged 8-16 yr. Results showed significant improvement in executive functions after treatment with atomoxetine for 4 wk or 12 wk including improved shifting and flexibility of attention in the IED; improved spatial short-term memory in the SSP; improved sustained attention and increased response inhibition in the RVIP; improved spatial working memory in the SWM; and improved spatial planning and problem solving in the SOC. Our findings suggested that atomoxetine was associated with significant improvement in various non-verbal executive functions among boys with ADHD, in addition to its well-known efficacy in ADHD-related symptom reductions. However, owing to lack of a placebo-controlled trial design, the findings should be interpreted with caution that changes in performance may be due to practice effects.