ADHD News & Research

Boys and Girls with ADHD: Cerebellum Size Matters

Brain differences between boys and girls with ADHD may offer further explanation of gender-related symptom patterns.

April 25, 2017

Every child with ADHD is different, but experts agree that certain symptoms tend to fall along gender lines. Boys with ADHD are more hyperactive and impulsive, while girls with ADHD often demonstrate more inattentive symptoms. It’s long been debated whether biological sex or societal gender roles contributes to this symptom disparity. Now, a small new study may provide the next piece of the puzzle, finding that boys and girls with ADHD had different-sized cerebellums — the area of the brain responsible for coordination and linked to cognitive functions like attention.

The study, presented March 25 at the annual meeting of the Cognitive Neuroscience Society, looked at 90 children between the ages of nine and 12. The children were closely split along gender lines — 50 girls and 40 boys — and a little over half of them had been formerly diagnosed with ADHD. MRI scans of each child found that both boys and girls with ADHD had significantly smaller cerebellum volumes than their counterparts without ADHD.

But the boys and girls with ADHD differed in where their cerebellums were smaller, with boys demonstrating more severe differences in the areas responsible for higher-order motor functions like planning behavior and regulating attention. Girls’ brains were weaker in the areas that direct more basic motor functions, like hand-eye coordination, precision, and timing.

Past studies on boys’ and girls’ brains have found other key differences in the brain, particularly in the premotor and primary motor cortexes. Boys with ADHD are more likely than girls to display abnormalities in these regions, which — like the cerebellum — are involved in planning and self-control.

The study was small, but it adds to the body of work about brain differences among those who have ADHD, says lead author Stewart Mostofsky — possibly helping to explain why girls with ADHD behave differently than boys. Mostofsky and his team say they plan to look at more than 400 children in the next few months, to see if their findings hold up to further scrutiny.