Concussions may contribute to a unique form of ADHD in children
Children and adults with a history of brain injury have been shown to be at a heightened risk for developing attention-deficit hyperactivity disorder compared to the average person, but new research suggests they aren’t developing your typical case of ADHD.
According to a study published in the journal Biological Psychiatry, children with a history of brain injury develop a unique form of ADHD distinct from the genetically-rooted variation seen in individuals with no history of brain injury.
The researchers found that those with both ADHD symptoms and a history of mild TBI showed no increased genetic risk for ADHD, while developmental ADHD is partially attributed to abnormalities in a set of genes.
“This article suggests that there are at least two forms of ADHD. One that is an expression of a risk inherited within families and the other which develops after traumatic brain injury,” said John Krystal, MD, Editor of Biological Psychiatry. “The latter is of particular interest in light of the growing evidence that contact sports and combat are associated with higher rates of traumatic brain injury than we previously recognized.”
“Mild traumatic brain injury (which includes concussion) is very common in adolescents; epidemiological data show that approximately 1 in 5 report a previous mild traumatic brain injury,” said senior author Anne Wheeler, Ph.D., of SickKids Research Institute and University of Toronto, Canada.
This is particularly concerning considering some studies indicate up to 50% of children who experience TBI develop ADHD symptoms not long after the injury. It should be noted that the majority of these symptoms resolve over time, though some progress to a clinical diagnosis of ADHD.
For the study, a team of researchers led by Sonja Stojanovski, a doctoral student in Dr. Wheeler’s laboratory, compared the genetic risk and origins of ADHD in 418 youth with a history of TBI and 3,193 with no brain injury history. All participants were between 8- and 22-years-old.
Based on their findings, there was no link in those with a history of TBI, indicating these children did not share a genetic link making them more vulnerable to ADHD after brain injury.
The team also searched for signs of the abnormalities in brain structure associated with ADHD. At first, it appeared the group with TBI shared similar signs of abnormalities, but when the team investigated further they found these changes were actually distinct.
“When thinking about treating youth with ADHD it is important to understand what the underlying causes are and how they may differ from person to person to move towards a personalized medicine approach,” said Dr. Wheeler.