Study: Brain differences found in children with ADHD
MelissaJenco, News Content Editor
As many as five brain regions may not be fully developed in children with attention-deficit/hyperactivity
disorder (ADHD), according to a new imaging study.
“The results from our study confirm that people with ADHD have differences in their
brain structure and therefore suggest that ADHD is a disorder of the brain,” lead
author Martine Hoogman, Ph.D., said in a news release. “We hope that this will help
to reduce stigma that ADHD is ‘just a label’ for difficult children or caused by poor
Worldwide, about 5.3% of children have ADHD, and symptoms persist into adulthood for
about two-thirds, according to the study “Subcortical brain volume differences in
participants with attention deficit hyperactivity disorder in children and adults:
a cross-sectional mega-analysis” (Hoogman M, et al. Lancet Psychiatry. Feb. 15, 2017, http://bit.ly/2knqMW5).
With funding from the National Institutes of Health, researchers from the international
ENIGMA ADHD Working Group embarked on what they said is the largest study performed
on brain differences in people with and without ADHD. They analyzed MRI data from
1,713 people with ADHD and 1,529 controls ranging in age from 4 to 63 years.
The team found those with ADHD had smaller brain volumes in the accumbens, amygdala,
caudate, hippocampus and putamen regions. Intracranial volume also was lower. They
dubbed ADHD a “disorder or brain maturation delay” and said structural differences
were greatest for children. In adults, there were no significant differences between
those with ADHD and the control group.
The research confirms previous findings on the caudate and putamen and shows the impact
is bilateral, the study said. The findings on the accumbens, amygdala and hippocampus
were new. The large impact seen in the amygdala, which regulates emotions, may change
the way ADHD is viewed.
“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,” Dr. Hoogman said. “Similar
differences in brain volume are also seen in other psychiatric disorders, especially
major depressive disorder.”
However, neither a comorbid psychiatric disorder nor psychostimulant medications appeared
to cause the brain differences of people in the study with ADHD, authors wrote.
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.
“This study represents an important contribution to the field by providing robust
evidence to support the notion of ADHD as a brain disorder with substantial effects
on the volumes of subcortical nuclei,” they wrote. “Future meta-analyses and mega-analyses
will need to investigate medication effects as well as the developmental course of
volumetric differences in this disorder.”