Dear parents, take note. Pre-schoolers with ADHD symptoms may have reduced brain size

Pre-schoolers with symptoms of Attention-Deficit/Hyperactivity Disorder (ADHD) may have reduced brain volumes in regions essential for behavioural control, says a new study. ADHD is the most commonly diagnosed form of psychopathology during the pre-school years, and during early childhood it is associated with significant long-term health.

The study represents the first comprehensive examination of cortical brain volume in pre-school children with ADHD and provides an indication that anomalous brain structure is evident in the early stages of development. According to the researchers, the findings can help in determining new ways to predict which children are most at risk for developing ADHD.

“These findings confirm what parents have known for a while — even in very young children, ADHD is a real biological condition with pronounced physical and cognitive manifestations,” said lead author of the study, E. Mark Mahone from the Kennedy Krieger Institute. For the study, published in the Journal of the International Neuropsychological Society, researchers studied the brain development of 90 medication-naive pre-schoolers between the ages of four and five years. They used high-resolution anatomical MRI scans along with cognitive and behavioural measures.

“MRI research in children can be challenging — particularly so for young children with ADHD — as it requires them to lie still for periods up to 30-40 minutes,” said Mahone. “To address this challenge, we employed an individualised behavioural desensitisation procedure using a mock scanner to help prepare the children for the scans, leading to a nearly 90 per cent success rate.” The study found that pre-schoolers with ADHD showed significantly reduced brain volume across multiple regions of the cerebral cortex, including the frontal, temporal and parietal lobes. The brain regions showing greatest ADHD-related reductions included those known to be critical for cognitive and behavioural control and predictability of behavioural symptoms.