ADHD linked with smaller brain volumes not bad parenting: research

Children with attention-deficit hyperactivity disorder have several brain regions that are slightly smaller than usual, more evidence that the disorder should be considered a neurological condition, a new study says.

All 3,242 people had an MRI scan to measure their overall brain volume, as well as the size in seven regions thought to be linked to ADHD.

The study, which was funded by the National Institutes of Health, appeared in the Wednesday (Feb. 15th) edition of the journal Lancet Psychiatry. The researchers also looked at the effect of age, gender, medication and other psychiatric disorders.

According to them, the amygdala's connection to ADHD is through the brain region's role in emotion regulation while the nucleus accumbens is related to emotional and motivational problems with the condition because of the role it plays in reward processing.

She says that the "unprecedented size" of their study is crucial because it helped to identify the "very small - in the range of a few percent" differences in brain region sizes.

Despite the large numbers of participants of all ages, the study was not created to investigate how ADHD might develop over a person's lifetime. A new study reveals information that suggests that ADHD might be a brain disorder.

The differences observed in their study were most prominent in children, but also present in adults with the condition. The hippocampus' role in ADHD is believed to have something to do with emotion and motivation as well.

Notably, no differences were found in the brain size of people who took ADHD drugs and those who did not.

Further, these differences were most prominent in the brains of children with ADHD, and less obvious in adults with the disorder, a finding that might be important in challenging beliefs that ADHD is a label for hard children or the result of poor parenting, the researchers said.

'This is a disorder of the brain just like clinical depression, schizophrenia and bipolar disorder - also associated with abnormal brain volumes. "This is definitely not the case, and we hope that this work will contribute to a better understanding of the disorder", said study author Martine Hoogman. Evidence has been revealed in scans that show structural differences in the brains of sufferers.

The research was praised by Columbia University's Jonathan Posner as "an important contribution" to the study of the condition. 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.