Novel Imaging Technique Reveals Brain Abnormalities in Children With ADHD

Novel Imaging Technique Reveals Brain Abnormalities in Children With ADHD

BALTIMORE, Md -- November 17, 2008 -- A study published early online in the American Journal of Psychiatry for the first time reveals shape differences in the brains of children with attention deficit hyperactivity disorder (ADHD), which could help pinpoint the specific neural circuits involved in the disorder.

Researchers used large deformation diffeomorphic mapping (LDDMM), which allowed them to examine the precise shape of the basal ganglia.

The study found that boys with ADHD had significant shape differences and decreases in overall volume of the basal ganglia compared to their typically developing peers. Girls with ADHD did not have volume or shape differences, suggesting sex strongly influences the disorder's expression.

Previous studies examining the basal ganglia in children with ADHD were limited to volume analysis and had conflicting results, with some reporting a smaller volume and some reporting no difference in volume.

LDDMM provides detailed analysis of the shape of specific brain regions, allowing for precise examination of brain structures well beyond what has been examined in previous MRI studies of ADHD.

In the study, LDDMM was used to map the brains of typically developing children in order to generate a basal ganglia template. After creating LDDMM mappings of the basal ganglia of each child with ADHD, statistical analysis was conducted to compare them to the template.

Initial volume analysis revealed that boys with ADHD had significantly smaller basal ganglia volumes compared with typically developing boys. Moving beyond the standard volume analysis, the LDDMM revealed shape abnormalities in several regions of the basal ganglia. Comparison of the standard volume and LDDMM analysis of girls with ADHD and their typically developing peers failed to reveal any significant volume or shape differences.

The multiple shape differences found in boys with ADHD suggest that the disorder may not be associated with abnormalities in 1 specific neural circuit. Rather, it appears the disorder involves abnormalities in parallel circuits, including circuits important for the control of complex behaviour and more basic motor responses. Findings revealing abnormalities in circuits important for basic motor response control may be crucial to understanding why children with ADHD have difficulty suppressing impulsive actions.

"This study represents a major advancement in our ability to examine the neuroanatomic features of ADHD and other developmental disorders," said senior author Stewart H. Mostofsky, MD, Department of Developmental Cognitive Neurology, Kennedy Krieger Institute, Baltimore, Maryland.

"Using LDDMM, we can more accurately measure the impact of ADHD on brain development, which will not only bring us closer to unlocking the biological basis of the disorder, but help us better diagnose and treat patients."

SOURCE: Kennedy Krieger Institute