Methylphenidate Treatment and Dyskinesia in Children with Attention-Deficit/Hyperactivity Disorder

Objectives: Case reports suggest a relationship between methylphenidate treatment and dyskinesia in attention-deficit/hyperactivity disorder (ADHD). The aim of the current study was (a) to investigate abnormal involuntary movements of children with ADHD before and after the administration of methylphenidate and (b) to investigate the effect of a provocative assessment method used to make latent dyskinesia visible, which is included in the Abnormal Involuntary Movement Scale (AIMS). Methods: Participants, aged 6-18, were recruited from a Child and Adolescent Psychiatric Hospital and Outpatient Clinic (Vadaskert Foundation), Budapest, Hungary. Using a structured diagnostic interview (Mini International Neuropsychiatric Interview Kid), 37 children were included in the ADHD group and 34 children in the control group. The AIMS was used to observe and score dyskinesia. Results: There was a significant difference between the baseline total AIMS score in the ADHD and the control groups, with the ADHD subjects evidencing substantially higher severity than controls. Provocation, as applied with the administration of the AIMS, significantly increased the AIMS total score in both groups. The administration of methylphenidate had no effect on the total score of the AIMS. In the ADHD group, we observed a significant negative relationship between the patients' age and the overall severity on the AIMS. In contrast, in the control group we detected a significant positive relationship between the patients' age and the overall severity on the AIMS before and no relationship after provocation. Conclusions: Methylphenidate-treated children with ADHD had more dyskinesia than children in the control group. Dyskinesia did not worsen after a single dose of methylphenidate. Higher dyskinesia scores in the methylphenidate-treated younger age group warrant caution in the methylphenidate treatment of ADHD; however, further studies are needed to clarify the possible causal relationship between dyskinesia and methylphenidate treatment and/or age and/or the disease itself.