Imaging Study Confirms Brain Differences in People With ADHD

The researchers say that the findings - from brain images of more than 3,200 people - provide strong evidence that ADHD is a disorder of the brain.

The condition is linked with inattention, hyperactivity and strong impulses and is thought to affect one in 20 under-18s. All study subjects underwent MRI scans to measure overall brain volume as well as the size of seven of the brain regions believed to be linked to the condition: the hippocampus, amygdala, nucleus accumbens, putamen, caudate nucleus, thalamus, and pallidum.

The people with ADHD showed slower development of five brain regions.

The brains of sufferers of attention deficit hyperactivity disorder (ADHD) are slightly smaller than those not suffering from the condition, according to a study.

"Worldwide cooperation is therefore an absolute must", Martine Hoogman, researcher at Radboud UMC and lead author on the study paper, said.

Based on their findings, the researchers found that five of the seven brain regions were smaller in those diagnosed with ADHD.

"We hope that this will help reduce stigma that ADHD is "just a label" for hard children or caused by poor parenting", said the study's leader author, Martine Hoogman of Radboud University Medical Center in the Netherlands, in a statement reported by AFP.

The study is the largest review of ADHD patients' brain scans ever conducted.

The global team of researchers measured the differences in the brain structure of 1,713 people with a diagnosis of ADHD and 1,529 without, all aged between four and 63-years-old.

"These differences are very small - in the range of a few percent - so the unprecedented size of our study was crucial to help identify these". The researchers also looked at the effect of age, gender, medication and other psychiatric disorders.

They found no difference between people who were taking or had taken ADHD drugs, and those who had never taken such medications - suggesting that the brain changes were not caused by psychostimulants. The link between ADHD and the hippocampus could perhaps arise from that region's involvement in motivation and emotion, they suggest.

This is not the first time that brain volumes have been linked to ADHD but previous studies had small sample sizes that rendered results inconclusive.

The differences between the two types of brain are not monumental however, according to the study's lead author, Martine Hoogman.

In a related commentary, Claudia Lugo-Candelas, Ph.D., and Jonathan E. Posner, M.D., praised the group's collaboration on such a large study.

People with ADHD have a part of their brains that is less developed. These areas are primarily involved in processing emotions and shed new light on some of the non-thinking aspects of ADHD.

  • Lila Blake