Study claims people with ADHD have slightly smaller brains

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Child with ADHD during activity therapy. Image: tomorn pukesorn/Shutterstock

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Despite societal reasons being given for the significant rise in ADHD diagnoses in recent years, new research is claiming that those with the condition have physically smaller brains.

ADHD, or attention deficit hyperactivity disorder, is a condition that results in selective inattentiveness, particularly during childhood.

US figures cited last year showed that in 2003, 7.8pc of children in a certain age group were diagnosed with ADHD, but by 2011, this had risen to 11pc.

Several regions affected

A group of Dutch researchers from Radboud University Nijmegen Medical Centre has conducted the largest analysis of brain scans of people with ADHD, finding that those with the disorder actually have a physical difference in their brains.

Describing these organs as having “structural differences”, the team said that seven regions – and the overall brain volume – were found to be smaller than those in people who do not have ADHD.

The affected regions include the amygdala, which is involved in the regulation of emotion. The differences were most prominent in children.

Only a small difference

The findings were calculated from a survey of of 1,713 people with ADHD and 1,529 people without, and has now been published in the journal The Lancet Psychiatry.

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

“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,” she said.

“Similar differences in brain volume are also seen in other psychiatric disorders, especially major depressive disorder.”

Attempting to reduce stigma

The study also took into account people who had taken medication to treat ADHD, such as methylphenidate, more commonly known as Ritalin.

Based on the findings of Hoogman and her team, there appeared to be no noticeable difference in brain size or volume, suggesting that the brain changes were not caused by psychostimulants.

Hoogman said: “We hope that this will help to reduce stigma that ADHD is ‘just a label’ for difficult children, or caused by poor parenting.”

Commenting on the study from an independent perspective, Jonathan Posner of Columbia University, who works in the field of ADHD science, described these findings as an “important contribution”.

This study follows a recently released research paper from Trinity College Dublin, which said it was honing in on the genes that propagate disorders such as ADHD, as well as autism, schizophrenia and epilepsy.

Colm Gorey is a journalist with Siliconrepublic.com

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