CHICAGO – Children with attention-deficit hyperactivity disorder have anatomical brain abnormalities that can be seen with a novel technique called diffusion tensor imaging.
“Our hope is, in the future, to be able to diagnose ADHD with this technique,” said lead investigator Manzar Ashtari, Ph.D., of North Shore-Long Island Jewish Health System in New Hyde Park, N.Y.
Speaking at a press conference at the annual meeting of the Radiological Society of North America, Dr. Ashtari explained that until now, imaging of the brain in patients with ADHD has revealed mostly “macroscopic” findings.
“For example, we know that the frontal lobe and cerebellum are smaller in these patients.” But she said her work with diffusion tensor imaging (DTI) looks “deeper”–at a more microscopic level–showing abnormalities in the corticopontocerebellar circuit, the fiber pathways that communicate between the frontal lobe and the cerebellum.
The study compared DTI of the brain in 18 children with ADHD, aged 7–11 years, and 15 healthy controls matched for age, sex and socioeconomic status.
“We found abnormalities in the fiber pathways in the frontal cortex, basal ganglia, brain stem, and cerebellum in the ADHD patients,” she said, explaining that these areas of the brain regulate attention, impulsive behavior, motor activity, and inhibition.
“These findings suggest that the circuit which connects the frontal lobe and the cerebellum is not efficient in ADHD,” she said.
Dr. Ashtari was also colead investigator on a second study that used DTI to compare the brain anatomy of 20 children with ADHD, half of whom were medicated for their condition, and half of whom were medication naïve.
Fiber pathway abnormalities are less pronounced in children who have been treated with stimulant medication, compared with those who have not.
“These results are definitely very exciting,” said Dr. Ashtari. “They suggest that perhaps the medication is doing something to normalize the brain abnormalities, such as remyelinating the axons.”
However, she cautions against jumping to the conclusion that the study shows stimulants can reverse, or partially correct, the brain abnormalities seen in ADHD.
“Other studies into the effect of medication have shown that the white matter of the brain increases to close to normal in medicated children. But medicated children also are usually older.
“So could the improvement be just an effect of age–as the brain grows?” she said in an interview.
“The more conclusive study will be to follow drug-naïve children prospectively and then see what happens when you medicate them,” she said.
Dr. Ashtari added that her team has received funding to start such a study of drug-naïve children.
While brain imaging using MRI has mostly revealed macroscopic findings, DTI shows a more microscopic view.
DTI shows frontal cortex and cerebellum abnormalities in an ADHD patient. Photos courtesy Dr. Manzar Ashtari