Efficacy of methylphenidate in children with attention-deficit hyperactivity disorder and learning disabilities: a
Natalie Grizenko1, Mamatha Bhat, George Schwartz
1Department of Psychiatry, McGill University and Division of Child and Adolescent Psychiatry, Douglas Hospital, Montréal, Que. grinat@douglas.mcgill.ca
Insights
Children with ADHD and learning disabilities show a poorer response to methylphenidate (MPH). Mathematics disability significantly impacts MPH effectiveness, suggesting additional therapies may be needed for these children.
Area of Science:
- Neuroscience
- Pediatrics
- Psychiatry
Background:
- Attention-deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder.
- Comorbid learning disabilities (LD) frequently occur in children with ADHD.
- Methylphenidate (MPH) is a common stimulant medication for ADHD.
Purpose of the Study:
- To investigate differential responses to MPH in children with ADHD and comorbid LD versus ADHD alone.
- To identify specific learning disabilities that influence MPH treatment outcomes.
Main Methods:
- A prospective, double-blind, placebo-controlled, randomized 2-week crossover trial was conducted.
- Ninety-five children (aged 6-12) meeting DSM-IV ADHD criteria participated.
- Learning ability was assessed using standardized tests; clinical response to MPH was the primary outcome measure.
Main Results:
- Children with ADHD and LD showed a significantly lower response rate to MPH (55%) compared to those without LD (75%).
- This reduced response was primarily driven by children with mathematics disability.
- Children with reading disability did not exhibit a significantly poorer response to MPH.
Conclusions:
- Comorbid learning disabilities, particularly mathematics disability, are associated with a diminished response to MPH in children with ADHD.
- These findings suggest that children with ADHD and mathematics learning disabilities may require additional therapeutic interventions beyond MPH.
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).
Conclusion:
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.
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