MRI hints at abnormality in psychopathic ADHD children

A region of the brain associated with motor control may be abnormal in children with attention deficit hyperactivity disorder (ADHD) and psychopathic traits, according to a recent MRI study.

Tasha McMahon Wellington and colleagues analyzed 24 archived MRI scans, 12 from children with no ADHD symptoms and 12 from children with symptoms of "combined" ADHD (involving both inattention and hyperactivity). All 12 of the ADHD children also had psychopathic traits, with about one-third scoring in the mild to moderate psychopathy range and two-thirds scoring in the high range, although only three met full criteria for psychopathy. The researchers focused on an area of the brain called the putamen, which is part of the basal ganglia. (Abnormalities of several other basal ganglia structures, particularly the caudate, are already implicated in ADHD.)

"Children in the ADHD group," the researchers report, "more often had a larger right putamen than left, whereas control children had larger left putamen than right."

This finding, they say, is indirectly supported by an earlier study (Teicher et al., 2000) that found decreased blood flow to the putamen in ADHD, particularly on the left side. "Teicher et al. found that measures of hyperactivity and inattention could be accounted for by deficits in blood flow to the putamen alone," Wellington and colleagues say, "and the deficits in blood flow and behavior were both attenuated by methylphenidate [Ritalin, the most common treatment for ADHD]." The researchers note, too, that putamen lesions caused by strokes or brain injuries can lead to secondary attention deficit disorder.

Noting that their ADHD subjects also had psychopathic traits, the researchers say that their findings may relate to the co-occurrence of both disorders. It is likely, they say, that children with both problems have more brain abnormalities than children with either disorder alone.