Frequency of comorbid disorders and their impact on response to methylphenidate treatment in children with ADHD

Attention Deficit Hyperactivity Disorder (ADHD) is a common neurobehavioral disorder that affects the educational، social and familial functions of children. ADHD has many comorbid psychiatric disorders which increase the future problems in these children. This study aimed to evaluate the effect of comorbid psychiatric disorders on the response to Methylphenidate in children with ADHD. This study was a descriptive research in the first step and a clinical trial، in the second step. Fifty children with ADHD (aged 6 to 12) referred to child psychiatry clinic of Sheikh Hospital were recruited in the study through consecutive sampling. The diagnosis of ADHD and comorbid psychiatric disorders were made by a board certified child psychiatrist based on DSM-IV-TR criteria via the clinical interview and Kiddie-Schedule for Affective Disorders and Schizophrenia (K-SADS). After obtaining informed consent from mothers Methylphenidate was started based on their age and weight and continued for four weeks. ADHD Rating Scale was completed by mothers before starting the medication and after four weeks. The level of improvement and treatment response was estimated based on test results and clinical judgment of psychiatrist. Statistical analysis was done by McNemar and chi square tests using SPSS version 19. 60% of total 50 patients with the disorder had a good response to treatment. 72% of children with ADHD had at least one comorbid psychiatric disorder. The most common comorbidities were: Anxiety disorders in 58%، Disruptive behavior disorders in 54%، Tic disorders in 12 % and elimination disorders in 10% of children. Children with ADHD without any comorbidity had better treatment response than children with comorbidities (p<0. 05). In evaluation of treatment response in each comorbidities، there were significant differences between children with good and poor response in anxiety and disruptive behavior disorders (p<0. 05). These differences were not significant in tic and elimination disorders (p>0. 05). Regarding treatment response، there was no significant difference between age، sex، and subtype of ADHD in children with and without comorbidities (p>0. 05). ‍ Presence of ADHD psychiatric comorbidities leads to changes in response to Methylphenidate and reduces the treatment response. Response to this treatment may be related to the type of comorbidities.