Clinical and Neuropsychological Factors Associated with Treatment Response and Adverse Events of Atomoxetine in Children with Attention-Deficit/Hyperactivity Disorder

OBJECTIVES: The objective of this study was to investigate clinical and neuropsychological factors associated with treatment response and adverse events of atomoxetine in children with attention-deficit/hyperactivity disorder (ADHD) in Korea. METHODS: Children with ADHD were recruited at the Department of Psychiatry of Asan Medical Center from April 2015 to April 2018. Diagnoses of ADHD and comorbid psychiatric disorders were confirmed with the Kiddie-Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version. The subjects were subsequently treated with atomoxetine for 12 weeks and illness severity was scored using the ADHD Rating Scale, Clinical Global Impression-Severity scale (CGI-S) and/or Improvement scale (CGI-I), at pre- and post-treatment. They also completed the Advanced Test of Attention (ATA), while their caregivers completed the Korean Personality Rating Scale for Children (KPRC) at pre- and post-treatment. Independent t-test, Fisher’s exact test, χ(2) test, mixed between-within analysis of variance and correlation analysis were used for statistical analysis. RESULTS: Sixty-five children with ADHD (mean age: 7.9±1.4 years, 57 boys) were enrolled, of which, 33 (50.8%) were treatment responders. Scores on the social dysfunction subscale of the KPRC (p=0.021) and commission errors on the visual ATA (p=0.036) at baseline were higher in treatment non-responders than in responders; however, the statistical significances disappeared after adjusting for multiple comparisons. Mood changes were also observed in 13 subjects (20.0%), and three of them discontinued atomoxetine due to this. Additionally, atomoxetine-emergent mood change was observed more frequently in girls (p=0.006), while the intelligence quotient (p=0.040) was higher in those subjects with mood changes than in those without. CONCLUSION: The results of our study suggest that clinical and neuropsychological factors could be associated with treatment response or adverse events of atomoxetine in children with ADHD. Further long-term studies with larger samples are needed.