Imaging Studies Detect Brain Abnormalities in Adult ADHD

Article excerpt

BOSTON -- The brains of adults with attention-deficit/hyperactivity disorder have distinct structural and functional abnormalities in regions associated with executive functioning and attention control, new imaging studies by investigators at Massachusetts General Hospital show.

The early findings support the contention that adult attention-deficit/hyperactivity disorder (ADHD) is a valid disorder associated with persistent biologic features, said Larry J. Seidman, Ph.D., director of neuroimaging studies at the Massachusetts General Hospital pediatric psychopharmacology unit. Dr. Seidman presented the findings at the annual meeting of the American Academy of Child and Adolescent Psychiatry.

Multiple neuroimaging studies have identified gray and white matter volume deficits in the brains of children with ADHD, particularly in the prefrontal and anterior cingulate cortex (ACC) regions, Dr. Seidman said. To determine whether such changes are consistent in adults diagnosed with ADHD, he and his colleagues conducted structural magnetic resonance imaging (MRI) studies in 24 adults with DSM-IV ADHD and 18 age-, sex-, and intelligence-matched controls, with a focus specifically on prefrontal, ACC, and total gray matter volumes.

Relative to controls, no significant differences were found in the whole brain or total cerebral volume. However, "the ADHD adults had significantly smaller overall cortical gray matter and significantly greater white matter volumes," Dr. Seidman reported. All cortical regions were smaller in the ADHD adults, but only the frontal lobe and medial paralimbic areas were significantly smaller, he said, and noted that the most substantial volumetric differences were observed in the ACC and the superior frontal gyrus.

The investigators compared these adult ADHD findings to those of a meta-analysis they had performed of 22 extant structural MRI studies of ADHD in children and adolescents, which also revealed widespread reductions for ADHD subjects, compared with controls. …