Putamen Underactive In Boys With Attention-Deficit Hyperactivity Disorder

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WESTPORT (Reuters Health) - Symptoms of attention-deficit hyperactivity
disorder (ADHD) may be linked to abnormalities in the putamen, according to
results obtained using a new type of functional magnetic resonance imaging.

Dr. Perry F. Renshaw, of McLean Hospital in Boston, Massachusetts, told
Reuters Health that his team used T2 relaxometry, which indirectly measures
blood flow in the striatum, and that it provided much greater resolution than
conventional functional MRI and made it easy to compare subjects. "We think
we have discovered something that no one else has shown," he said.

Eleven boys with ADHD and six healthy boys underwent T2 relaxometry while
performing a computerized attention test. The children with ADHD were tested
after they took placebo or methylphenidate for 1 week, according to the research team's report in the April issue of Nature Medicine.

When the researchers compared the controls with the ADHD patients on
placebo, they found no significant differences between the groups in bilateral T2
relaxation time for the thalamus and the caudate nucleus. But in the putamen,
bilateral relaxation times were higher in ADHD patients than in controls.

"Relaxation times strongly correlated with the child's capacity to sit still and his accuracy in accomplishing a computerized attention task," Dr.Renshaw's team reports.

In both the left and right putamen, relaxation times were significantly altered in ADHD patients by treatment with methylphenidate, according to the report. However, "the response was strongly related to the subject's unmedicated activity state," the authors write.

It makes sense that children with ADHD would have abnormalities in the putamen, according to Dr. Renshaw, since this brain region is involved in controlling motor activity.

Dr. Renshaw said that T2 relaxometry might eventually be used to develop objective brain-based diagnostic criteria and to monitor the effects of various therapies.

Study coauthors are Carl Anderson, PhD; Ann Polcari, RN; Carol Glod, PhD, and Perry Renshaw, MD, PhD, all of McLean Hospital; and Luis Maas, MD, of McLean Hospital and the Harvard-MIT Division of Health Sciences and Technology.

The study was funded by the National Institute of Mental Health and the National Institute for Drug Abuse.

McLean Hospital is the largest psychiatric teaching affiliate of Harvard Medical School, an affiliate of Massachusetts General Hospital and a member of Partners HealthCare System.