Evaluation of the effect of methylphenidate by computed tomography, electroencephalography, neuropsychological tests, and clinical symptoms in children with attention-deficit/hyperactivity disorder: A prospective cohort study

Abstract

Background: Stimulant drugs are the most commonly used treatments for attention-deficit/hyperactivity disorder (ADHD), although the mechanism of action of these drugs is still not entirely understood. Objective: The aim of this study was to investigate the effects of the psychostimulant drug methylphenidate (MPH) on regional cerebral blood flow (rCBF), electrical activity of the brain, and clinical symptoms in children with ADHD using single-photon emission computed tomography (SPECT), electroencephalography (EEG), and neuropsychological tests. Methods: In this prospective cohort study, pediatric outpatients received MPH for 3 months at a mean dose of 1 mg/kg · d (range, 0.5–1.5 mg/kg · d). They were then administered the Wechsler Intelligence Scale for Children-Revised, the Bender Visual-Motor Gestalt Test (BGT), EEG, and SPECT of the brain. The parents and/or teacher of each child were asked to complete the Conners' Parent Rating Scale (CPRS), the Conners' Teacher Rating Scale (CTRS), and the Turgay Diagnostic and Statistical Manual of Mental Disorders Fourth Edition-based Child and Adolescent Behavior Disorders Screening and Rating Scale (T- DSM-IV-S). All of the evaluations were performed at baseline and after 3 months of MPH treatment. Each child underwent a Stroop test as an activation method 15 minutes before the SPECT procedure. Results: Sixty patients were assessed for inclusion. Twenty-one children (18 boys [85.7%], 3 girls [14.3%]; mean [SD] age, 9.7 [1.7] years; range, 8–13 years) with a diagnosis of ADHD were included in and completed the study. Mean (SD) BGT scores before MPH treatment compared with after MPH treatment were significantly decreased (9.8 [4.2] vs 6.3 [3.4]; Z = -3.27; P = 0.001). After treatment with MPH, the visual SPECT results suggested that low rCBF was normalized in the right frontotemporal areas in 10 children with ADHD. After treatment, 12 patients (57.1%) had no change in EEG activity, 5 (23.8%) had improvement, and 4 (19.0%) had worsening activity. Patients who had improvement or no worsening on EEG after MPH treatment were associated with significant improvement after MPH treatment compared with before treatment in mean (SD) CTRS scores (25.9 [14.3] vs 35.0 [14.4]; P = 0.003), teachers' T- DSM-IV-S total score (25.1 [14.2] vs 38.4 [18.7]; P = 0.005), and CPRS scores (mothers scores: 29.7 [16.6] vs 42.6 [17.2], P = 0.002; fathers' scores: 29.4 [16.8] vs 41.9 [23.7], P = 0.004). No significant difference was found in these scores in the patients whose EEG findings showed deterioration after MPH treatment. The quantitative values for SPECT observed before treatment compared with those observed after 3 months of MPH treatment were not found to be significantly different in any areas of the brain. Conclusions: MPH use over 3 months was associated with improvement from baseline in visual-motor function and behavioral disorders in these children and adolescents with ADHD. However, no significant difference in rCBF or electrical activity in the brain was observed in this small study.