A study of children and adults with attention deficit disorders suggests their brains may have structural differences, which could change the way the condition is understood.
The researchers looked at the brain volume of 1,713 people with ADHD and 1,529 people with out ADHD aged between 4 and 63 years.
The results of the study, which involved 1,713 people with ADHD and 1,529 people without the condition, were published in The Lancet Psychiatry. "Future meta-analyses and mega-analyses will need to investigate medication effects as well as the developmental course of volumetric differences in this disorder".
The regions affected included the amygdala, which is involved in the regulation of emotion.
But the differences are also really hard to spot, according to Hoogman, who says the brains of one group only differed by "a few percent - so the unprecedented size of our study was crucial to help identify these". Its ADHD project was four times the size of the previously largest study and was conducted at 23 locations in nine countries by 80 researchers, primarily psychiatrists and neuroscientists.
A new study confirms that ADHD, especially in children, such as this Maryland adolescent negotiating a laser maze, is a brain disorder.
Based on their findings, the researchers found that five of the seven brain regions were smaller in those diagnosed with ADHD.
The researchers speculate that the amygdala is linked to ADHD through the part it plays in controlling emotion, and the nucleus accumbens through the role it plays in reward processing.
Notably, no differences were found in the brain size of people who took ADHD drugs and those who did not. "This is definitely not the case, and we hope that this work will contribute to a better understanding of the disorder".
Other experts described the findings as interesting but said there wasn't enough information to link the brain differences to behavioural problems seen in people with ADHD.
New findings show that ADHD might be a brain disorder.
A new study, the largest ever of its kind, may shed light.
"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.
In a comment on the study, Jonathan Posner of Columbia University said it was an "important contribution" to the field of ADHD science. He also calls for further studies to track brain differences in the development of ADHD, and suggests that there should also be an investigation of any medication effects.