Effects of Atomoxetine and Osmotic Release Oral System-Methylphenidate on Executive Functions in Patients with Combined Type Attention-Deficit/Hyperactivity Disorder

Objective: The aim of this study was to evaluate and compare the effects of atomoxetine (ATX) and osmotic release oral system-methylphenidate (OROS-MPH) therapies on executive functions, activities, treatment response time, and adverse effects based on discernible clinical effects in children with combined type attention-deficit/hyperactivity disorder (ADHD). Methods: The study sample consisted of 43 children 7–12 years of age, who presented to the outpatient clinic with inattention, hyperactivity, and impulsivity for the first time, and were diagnosed as having combined type ADHD according to Diagnostic and Statistical Manual of Mental Disorders, 4th ed. (DSM-IV) criteria but had not previously used any medication for ADHD. The Wisconsin Card Sorting Test (WCST), Stroop Test TBAG Form (STP), and Visual Auditory Digit Span B (VADS B) were applied to all the patients included. Neuropsychological tests were repeated in 33 patients with good clinical recovery based on the Clinical Global Impressions-Improvement (CGI-I) scale (CGI-I ≤2) at the week in which clinical recovery was observed. The time limit for treatment response was set as 20 weeks. Results: It was found that there was significantly increased performance in executive functions with ATX and OROS-MPH in both groups. It was seen that although significantly increased performance was achieved in both perseveration and conceptual learning and reasoning domains by both agents, there was increased performance in more domains by the OROS-MPH group in WSCT. Mean doses were 1.31±0.37 mg/kg/day in the ATX group and 0.90±0.29 mg/kg/day in the OROS-MPH group. Comparable effectiveness (76.19% for ATX vs. 77.27% for OROS-MPH) and adverse effects (57.14% for ATX vs. 54.54% for OROS-MPH) were detected in both groups, whereas there was a significant difference in clinical response times between the groups (13 weeks for ATX vs. 7 weeks for OROS-MPH, p <0.001). Conclusions: At the end of the study, it was seen that clinical recovery achieved by ATX and OROS-MPH therapy was associated with improved cognitive processes, and that these agents do not only lead to behavioral changes but also to an improvement in cognitive processes. In addition, improvements in cognitive processes occurred simultaneously with behavioral recovery. Behavior is the result of neurocognitive processes, and further studies on the domains that these drugs affect, or the way in which these agents exert their effects, are needed.