Study finds children with brain injuries may have higher ADHD risk

Young children who are hospitalised with head injuries may be at higher than average risk for developing attention deficit hyperactivity disorder (ADHD) later on, a small study suggests.

US researchers examined data on 187 children, including 81 who were hospitalised  overnight for a traumatic brain injury (TBI) at some point from age 3 to 7, and 106 who were hospitalised with other injuries. None of the kids had ADHD at the start.

Altogether, over the next seven years, 48 children, or 26 per cent, developed symptoms of ADHD. Children with TBI were more than three times as likely to develop ADHD as kids with other kinds of injuries.

“Children with a history of traumatic brain injury, even those with less severe injuries, have an increased risk for the development of new-onset attention problems, potentially many years after injury,” said lead study author Megan Narad of Cincinnati Children’s Hospital Medical Center in Ohio.

 “The exact brain changes that lead to attention problems after brain injury are incompletely understood,” Narad said. “It is believed that there may be changes that occur at the cellular and structural levels in the brain, which affect how the different areas of the brain communicate with each other, but there is still a lot to learn about how brain development may be altered after an injury, especially in early childhood.”

ADHD, which is characterized by social and behavioral problems as well as challenges in school, is the most common psychiatric disorder among children with a history of traumatic brain injuries, researchers note in JAMA Pediatrics.

Up to about one in five kids with a TBI develops ADHD, roughly twice the diagnosis rate among typically developing school age children.

All of the kids in the current study were treated at hospitals in Ohio. Researchers surveyed the kids’ parents six times over the course of about seven years.

Among kids who developed symptoms meeting the definition of ADHD during the study, 13 had severe brain injuries, 6 had moderate brain injuries, 13 had complicated mild brain injuries, and 16 had been hospitalised  for injuries to other parts of the body.

With severe brain injuries, 62 per cent of kids who developed ADHD did so within the first year after injury.

At least half of the children with less severe brain injuries or injuries to other parts of the body who developed ADHD did so more than a year afterwards.

Children were more likely to develop symptoms of ADHD when their mothers had limited education, and kids with brain injuries also had a higher risk of ADHD when they lived in dysfunctional families.

The study wasn’t a controlled experiment designed to prove whether or how brain injuries might directly cause ADHD.

Another limitation is that it focused only on hospitalised  children, leaving out the majority of kids who get concussions or brain injuries that aren’t serious enough to warrant a hospital admission, the authors note.

Even so, the results add to the evidence linking traumatic brain injuries to ADHD, said Jack Tsao, a researcher at the University of Tennessee Health Science Center and the Memphis Veterans Affairs Medical Center. Much of the previous work in this area has focused on short-term outcomes, and the current paper provides fresh evidence of the longer-term impact of these brain injuries, Tsao, who wasn’t involved in the study, said by email.

 “Parents and the children’s physicians or other medical professions and teachers need to be aware of this and look for signs even many years after recovery may appear to be complete,” Tsao said.

While it’s not known exactly what causes ADHD to emerge, parents can provide children support after brain injuries that may help minimize the risk, Tsao added.

 “The recommendation for rehabilitation of children is to get them back into the classroom as soon as they are able to return to school/play even if only in a gradual fashion (half days early on for example),” Tsao said.