Long-term methylphenidate therapy in children with comorbid attention-deficit hyperactivity disorder and chronic multiple tic disorder

Background: This study examined changes in attention-deficit hyperactivity (ADHD) behaviors and mo tor and vocal ties during long-term treatment with methylphenidate. Methods: Thirty-four prepubertal children with ADHD and chronic multiple ti c disorder (who had participated in an 8-week. double-blind, placebo-contro lled methylphenidate evaluation) were evaluated at 6-month intervals for 2 years as part of a prospective, nonblind, follow-up study. Treatment effect s were assessed using direct observations of child behavior in a simulated (clinic-based) classroom and behavior rating scales completed by parents an d physician. Video tapes of the simulated classroom were scored by coders w ho were blind to treatment status. Results: There was no evidence (group data) that motor ties or vocal ties c hanged in frequency or severity during maintenance therapy compared with di agnostic or initial double-blind placebo evaluations, Behavioral improvemen ts demonstrated during the acute drug trial were maintained during follow-u p. There was no evidence (group data) of clinically significant adverse dru g effects on cardiovascular function or growth at the end of 2 years of tre atment. Conclusions: Long-term treatment with methylphenidate seems to be safe and effective for the management of ADHD behaviors in many (but not necessarily all) children with mild to moderate tic disorder. Nevertheless, careful cl inical monitoring is mandatory to rule out the possibility of drug-induced tic exacerbation in individual patients.