WEDNESDAY, Aug. 8 (HealthDay News) -- In children with attention-deficit/hyperactivity disorder (ADHD), a variation in the dopamine receptor D4 gene -- the 7-repeat allele -- is associated with tissue thinning in areas of the brain that control attention, according to a report published in the August issue of the Archives of General Psychiatry.
Philip Shaw, M.D., Ph.D., of the National Institute of Mental Health in Bethesda, Md., and colleagues studied 105 ADHD patients (average age 10.1) and 103 healthy controls who underwent magnetic resonance imaging and DNA testing. Six years later, the investigators performed a clinical evaluation of 67 (64 percent) of the ADHD patients.
In both patients and controls, the researchers found that the allele was associated with a thinner right orbitofrontal/inferior prefrontal and posterior parietal cortex. After six years, however, they found that ADHD patients with the allele had regained thickness in their right parietal cortex, a pattern they had previously associated with an improved clinical outcome.
"In children, gains in verbal knowledge are mirrored by change in the cortical thickness of speech areas," the authors write. "While our current study demonstrates changes in cortical thickness and symptoms occurring in tandem, a future goal is to refine further our appreciation of cortical thickness by examining the links between this neuroanatomical variable and putative cognitive endophenotypes for ADHD, such as response inhibition and working memory."
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