Variant Linked to Attention-Deficit Hyperactivity

June 26, 2008

In children with attention-deficit/hyperactivity disorder, those with the catechol-O-methyltransferase (COMT) Val108/158Met polymorphism are more likely to demonstrate poor task-oriented behavior, according to a report published online June 25 in Neuropsychopharmacology.

THURSDAY, June 26 (HealthDay News) -- In children with attention-deficit/hyperactivity disorder, those with the catechol-O-methyltransferase (COMT) Val108/158Met polymorphism are more likely to demonstrate poor task-oriented behavior, according to a report published online June 25 in Neuropsychopharmacology.

Sarojini Sengupta, M.D., of McGill University in Montreal, Canada, and colleagues conducted a double-blind, placebo-controlled crossover study of 188 patients aged 6 to 12 (159 boys and 29 girls) to assess the association between the polymorphism and task-oriented behavior, as well as the response of this behavior with methylphenidate treatment.

The researchers found that the COMT Val108/158Met polymorphism significantly modulated task-oriented behavior, and that children in the Met-Met and Val-Met genotype groups had significantly lower total Restricted Academic Situation Scale scores, which measure behavior in a simulated classroom, than children with the Val-Val genotype. They also found that the COMT Val108/158Met polymorphism was specifically associated with 'off-task' behavior.

"However, no genotype by treatment interaction was observed. These results suggest that the COMT Val108/158Met polymorphism modulates task-oriented behavior, but it does not modulate the response of this behavior with methylphenidate treatment," the authors write. "If these profiles are confirmed in a larger group of patients, this may help in understanding the pathogenesis of this very common childhood disorder."

One of the researchers received consultancy honoraria from Janssen-Ortho and Pfizer Canada.

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