ADHD, Dyslexia May Affect Evaluation of Concussion

August 18, 2020

Young people with certain learning disorders, such as attention-deficit disorder/attention-deficit/hyperactivity disorder (ADD/ADHD) and dyslexia, can perform worse on commonly used concussion tests, a new study shows.

"Our results suggest kids with certain learning disorders may respond differently to concussion tests, and this needs to be taken into account when advising on recovery times and when they can return to sport," lead author Matthew Stokes, MD, told Medscape Medical News.

Stokes is assistant professor of pediatrics and neurology/neurotherapeutics at the University of Texas–Southwestern Medical Center, Sports Medicine, Dallas, Texas.

The study was presented at the American Academy of Neurology Sports Concussion Virtual Conference, held July 31 to August 1.

The researchers analyzed data from participants aged 10 to 18 years who were enrolled in the North Texas Concussion Registry (ConTex). Participants had been diagnosed with a concussion that was sustained within 30 days of enrollment. The researchers investigated whether there were differences between patients who had no history of learning disorders and those with a history of dyslexia and/or ADD/ADHD with regard to results of clinical testing following concussion.

Of the 1298 individuals in the study, 58 had been diagnosed with dyslexia, 158 had been diagnosed with ADD/ADHD, and 35 had been diagnosed with both conditions. There was no difference in age, time since injury, or history of concussion between those with learning disorders and those without, but there were more male patients in the ADD/ADHD group.

Results showed that in the dyslexia group, mean time was slower (P = .011), and there was an increase in error scores on the King-Devick (KD) test (P = .028). That test assesses eye movements and involves the rapid naming of numbers that are spaced differently.

In addition, those with ADD/ADHD had significantly higher impulse control scores (P = .007) on the ImPACT series of tests, which are commonly used in the evaluation of concussion.

Participants with both dyslexia and ADHD demonstrated slower KD times (P = .009) and had higher depression scores and anxiety scores.

Stokes noted that a limiting factor of the study was that baseline scores were not available.

"It is possible that kids with ADD have less impulse control even at baseline, and this would need to be taken into account," he said. "You may perhaps also expect someone with dyslexia to have a worse score on the KD tests, so we need more data on how these scores are affected from baseline in these individuals. But our results show that when evaluating kids pre- or post concussion, it is important to know about learning disorders, as this will affect how we interpret the data."

At 3-month follow-up, there were no longer significant differences in anxiety and depression scores for those with and those without learning disorders.

"This suggests anxiety and depression may well be worse temporarily after concussion for those with ADD/ADHD but gets better with time," Stokes said.

Follow-up data were not available for the other cognitive tests.

Asked whether young people with these learning disorders needed a longer time to recover after concussion, Stokes said: "That is a million-dollar question. Studies so far on this have shown conflicting results. Our results add to a growing body of literature on this."

He stressed that it is important to include anxiety and depression scores on both baseline and post-concussion tests. "People don't tend to think of these symptoms as being associated with concussion, but they are actually very prominent in this situation," he noted. "Our results suggest that individuals with ADHD may be more prone to anxiety and depression, and a blow to the head may tip them more into these symptoms."

Discussing the study at a virtual press conference as part of the AAN Sports Concussion meeting, the co-director of the meeting, David Dodick, MD, Mayo Clinic, Scottsdale, Arizona, said: "This is a very interesting and important study which suggests there are differences between adolescents with a history of dyslexia/ADHD and those without these conditions in performance in concussion tests. Understanding the differences in these groups will help healthcare providers in evaluating these athletes and assisting in counseling them and their families with regard to their risk of injury.

"It is important to recognize that athletes with ADHD, whether or not they are on medication, may take longer to recover from a concussion," Dodick added. They also exhibit greater reductions in cognitive skills and visual motor speed regarding hand-eye coordination, he said. There is also an increase in the severity of symptoms. "Symptoms that exist in both groups tend to more severe in those individuals with ADHD," he noted.

"Ascertaining the presence or absence of ADHD or dyslexia in those who are participating in sport is important, especially when trying to interpret the results of baseline testing, the results of post-injury testing, decisions on when to return to play, and assessing for individuals and their families the risk of long-term repeat concussions and adverse outcomes," he concluded.

The other co-director of the AAN meeting, Brian Hainline, MD, chief medical officer of the National Collegiate Athletic Association, added: "It appears that athletes with ADHD may suffer more with concussion and have a longer recovery time. This can inform our decision making and help these individuals to understand that they are at higher risk."

Hainline said this raises another important point: "Concussion is not a homogeneous entity. It is a brain injury that can manifest in multiple parts of the brain, and the way the brain is from a premorbid or comorbid point of view can influence the manifestation of concussion as well," he said. "All these things need to be taken into account."

Attentional deficit may itself make an individual more susceptible to sustaining an injury in the first place, he said. "All of this is an evolving body of research which is helping clinicians to make better-informed decisions for athletes who may manifest differently.'

American Academy of Neurology Sports Concussion Virtual Conference.

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