Efficacy of methylphenidate in children with attention-deficit hyperactivity disorder and learning disabilities: a randomized crossover trial.
OBJECTIVE
To determine whether children with attention-deficit hyperactivity disorder (ADHD) and learning disabilities respond differently to methylphenidate (MPH) compared with children with ADHD only.


METHODS
We conducted a prospective, double-blind, placebo-controlled, randomized, 2-week crossover trial of MPH, during which response to MPH was assessed. Learning ability was appraised using the Wide Range Achievement Test, Revised (WRAT-R), for English-speaking students and the Test de rendement pour francophones for French-speaking students. The study was conducted at the Douglas Hospital, a McGill University-affiliated teaching hospital in Montréal. Ninety-five children, aged 6-12 years, who met the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV), criteria for ADHD participated in the study, which ran from 2001 to 2004. The outcome measure used was the Consensus Clinical Response, an indicator of the degree of clinical improvement shown when taking MPH.


RESULTS
The proportion of children with learning disabilities who responded to MPH (55%) was significantly smaller (chi(2)1 = 4.5, p = 0.034) than the proportion of children without learning disabilities who responded adequately to MPH (75%). This difference was mainly because of children with mathematics disability being particularly unresponsive to MPH (chi(2)1 = 4.5, p = 0.034). Children with reading disability did not show this pattern of poor response (chi(2)1 = 1.0, p = 0.33).


CONCLUSIONS
Children with ADHD and comorbid learning disability tended to respond more poorly to MPH. In particular, children with disability in mathematics responded less to MPH than those without disability in mathematics. Additional therapy may be indicated for this group of patients.
Grizenko
Natalie
N
Department of Psychiatry, McGill University and Division of Child and Adolescent Psychiatry, Douglas Hospital, Montréal, Que. grinat@douglas.mcgill.ca
Bhat
Mamatha
M
Schwartz
George
G
Ter-Stepanian
Marina
M
Joober
Ridha
R
D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy*; D000697:Central Nervous System Stimulants / Q000627:therapeutic use*; D002648:Child; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D007859:Learning Disabilities / Q000188:drug therapy*; D008297:Male; D008774:Methylphenidate / Q000627:therapeutic use*; D016896:Treatment Outcome
D000697:Central Nervous System Stimulants; D008774:Methylphenidate