High school and college athletes with a history of developmental disorders such as attention deficit-hyperactivity disorder (ADHD) and learning disability (LD) are 2 to 3 times more likely to self-report having experienced multiple concussions than those without such history, a first-of-its-kind study (Nelson et al 2015) finds.

The study was published online ahead of print in the Clinical Journal of Sports Medicine. 

Aggregating and using data from two previous studies of predominantly male football players, researchers also found that, even in players without history of concussion, individuals with ADHD reported more baseline symptoms (34% reported difficulty concentrating versus 10% in the control group), and that ADHD and LD were associated with poorer performance on paper-and-pencil baseline neurocognitive tests. They also found that athletes with ADHD and history of multiple concussions reported higher symptom levels at baseline than those with ADHD and fewer prior injuries.

The results of the study were consistent with prior studies suggesting that athletes with ADHD and/or LD are at increased risk for repetitive concussive injuries, and complement recent findings from a study in which NCAA Division I athletes with self-reported ADHD more commonly reported a history of concussion than those without.  

The findings, said lead author Lindsay Nelson of the Departments of Neurology and Neurosurgery at the Medical College of Wisconsin, made intuitive sense, and suggested that "caution is warranted in managing concussion" in these athletes, "given their elevated history of repeat injury (and possible increased risk for future reinjury)." 

"These findings imply that athletes with ADHD and/or LD may represent at-risk groups and may require tailored assessment and management strategies," said Nelson. The findings "underscore the potential importance of baseline [neurocognitive] testing in such special populations." (current concussion management guidelines do not advocate for routine baseline testing)

Areas for future study 

The study identified three areas for future study: (1) exploring how developmental disorders may affect response to concussions in the first few days or week after injury in order to determine the extent to which ADHD and LD alter the course of recovery; (2) exploring the chicken-or-egg question of whether the neurocognitive underpinnings of ADHD and LD, such as disinhibition, impaired self-monitoring, or increased reaction time during cognitively demanding tasks) lead these athletes to engage in high-risk behavior on the field, or instead whether ADHD/LD create a lower threshold for the occurrence of concussion and concussion signs; and (3)  to determine whether the finding that athletes with both ADHD and concussive histories reported more baseline symptoms was a reflection of lingering symptoms suggesting incomplete recovery from concussions or was because such athletes have more severe ADHD, which could jointly cause more symptoms and injury proneness. 

"The advent of new accelerometer technologies to enable the recording of head impacts in real time and correlation of biomechanical data with clinical measures may be especially informative" in understanding the factors predicting individual thresholds for concussive injury in ADHD/LD populations," Nelson said.

Should kids with ADHD avoid contact sports? 

The findings of the study support those of a recent study by researchers at Children's Hospital of Pittsburgh and the University of Chicago (Bonfield, et al 2013) finding that children with ADHD who sustain mild traumatic brain injury (mTBI) such as concussion are more likely to be moderately disabled after injury than those who sustain mTBI without ADHD.

The takeaway message for parents of these studies, says Rosemarie Scolaro Moser, Ph D, MomsTEAM's expert sports concussion neuropsychologist and Director of the Sports Concussion Center of New Jersey, is "that ADHD is another risk factor that should be considered in contact/collision sports. All kids need exercise, all kids benefit from sports, all kids are at risk for concussion. The parent's job is to minimize that risk."

"There is no clear evidence that says a child with ADHD should not play hockey, football, lacrosse or skateboard, ski, or play any other sport. But parents should be wise in considering all risk factors, whether ADHD, gender, history of headaches, number of previous head injuries/concussions, age and any other modifying factors when making decisions about starting or returning to a high-risk sport," says Dr. Moser. 

Bonfield CM, Lam S, Lin Y, Greene S. The impact of attention deficit hyperactivity disorder on recovery from mild traumatic brain injury. J Neurosurg: Pediatrics 2013. DOI:10.3171/2013/5.PEDS12424 (published online ahead of print, June 25, 2013) 

Nelson LD, Guskiewicz KM, Marshall SW, et al. Multiple Self-Reported Concussions Are More Prevelant in Athletes With ADHD and Learning Disability.  Clin J Sport Med. 2015 (published online ahead of print, April 24, 2015) 

Posted May 4, 2015