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ADHD affects white matter differently in boys, girls

Attention-deficit/hyperactivity disorder affects white matter differently in boys and girls, according to study findings in the Journal of the American Academy of Child and Adolescent Psychiatry.

“Sexual dimorphism is evident in attention-deficit/hyperactivity disorder (ADHD), including subtype prevalence, adverse outcomes, and neural phenotype. Neurobiological studies of ADHD suggest that boys show more abnormalities in motor and premotor structure and function, whereas girls differ from typically developing peers in prefrontal circuitry,” Lisa A. Jacobson, PhD, of Kennedy Krieger Institute, Johns Hopkins Hospital, Baltimore, and colleagues wrote.

To identify sex-specific differences in motor and premotor and prefrontal white matter microstructure related to ADHD, researchers applied diffusion tensor imaging to 120 children aged 8 to 12 years. Study participants included 60 children with ADHD and 60 typically developing children matched for age, IQ and handedness.

Researchers found sex-by-diagnosis interactions for fractional anisotropy in primary motor and medial orbitofrontal cortex.

Compared with typically developing children, boys with ADHD exhibited bilateral reductions in fractional anisotropy within primary motor while girls with ADHD showed higher fractional anisotropy in the medial orbitofrontal cortex.

Decreased fractional anisotropy within primary motor was associated with higher reaction time variability among boys and higher commission error rates among girls.

Decreased fractional anisotropy within the medial orbitofrontal cortex was associated with greater reaction time variability and commission error rates among all children with ADHD.

Based on the study findings, the researchers concluded that ADHD affects white matter differently in boys and girls. Boys appeared more affected in regions responsible for basic actions while girls exhibited more abnormalities in regions responsible for higher-level, top-down control. – by Amanda Oldt

Disclosure: Please see the full study for a list of all authors’ relevant financial disclosures.