ADHD May Be a Risk Factor for Sport-related Concussion in Teens and Young Adults
Key findings
- Among 79 student athletes ages 12 to 24 who had had at least one sport-related concussion, 47 (59%) were determined to have full or subthreshold attention-deficit/hyperactivity disorder (ADHD)
- In all but one of those 47 patients, ADHD preceded the first concussive event
- Post-concussion patients with ADHD were more likely than those without to have sustained more than one head injury
- Post-concussion patients with ADHD were significantly more symptomatic than those without and had significantly worse deficits in executive function, suggesting that they may have a more complicated course of recovery
A pilot study at Massachusetts General Hospital published in 2015 suggested that attention-deficit/hyperactivity disorder (ADHD) is a risk factor for mild traumatic brain injury. The core deficits of ADHD, which include poor impulse control, inattention and distractibility, make that connection plausible.
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In a larger study, Mary Iaccarino, MD, a physical medicine and rehabilitation specialist with the Sports Concussion Clinic at MassGeneral Hospital for Children, Joseph Biederman, MD, chief of the Clinical and Research Program in Pediatric Psychopharmacology and Adult ADHD, and colleagues have confirmed ADHD as an antecedent risk factor for sport-related concussion among adolescents and young adults. In addition, as they report in Neurology: Clinical Practice, ADHD may complicate the course of recovery from concussion.
Patients and Assessments
Without mentioning ADHD, the researchers recruited 79 Mass General patients who had sustained a sport-related concussion in the last 10 years and were 12 to 24 years of age. Those <18 years old were accompanied by a parent or guardian. When possible, parents of patients 18 to 24 years old were contacted for an indirect report.
Participants completed a two-hour assessment battery included:
- For diagnosis of ADHD:
- The ADHD module from the Kiddie Schedule for Affective Disorders and Schizophrenia, epidemiologic version was used
- Full ADHD was diagnosed if all Diagnostic and Statistical Manual of Mental Disorders: Fourth Edition criteria were met
- Subthreshold ADHD was diagnosed if patients were ≥12 years old at ADHD symptom onset and/or had four or five symptoms of ADHD on at least one of the modules (inattention or hyperactivity)
- For assessment of post-concussion symptoms:
- The British Columbia Post-concussion Symptom Inventory (BC-PSI) was adapted to include questions about the mechanism of injury, details of the injury and duration and severity of symptoms for up to three concussions; the most severe concussion reported was used in the study
- The Immediate Post-concussion Assessment and Cognitive Testing (ImPACT) was used to assess post-concussive symptoms and cognitive function
- For assessment of executive function:
- Parents of patients <18 years old completed the Behavior Rating Inventory of Executive Function (BRIEF) Parent Report; patients ≥18 years old completed the BRIEF-Adult Self-Report
Prevalence of ADHD in Student-Athletes with Concussion
The researchers determined that 23 (29%) of the 79 patients had full ADHD, including 11 of the 22 (50%) patients who were ≤17 years old and 12 of the 57 (21%) who were >17 years old. They note that those rates are almost five times higher than in the general U.S. population. An additional 24 patients (30%) had subthreshold ADHD.
Clinical Correlates of Sport-related Concussion
In all but one of the 47 post-concussion patients who had ADHD, the age at onset of ADHD preceded the age at the time of the first concussion. The patient who was the exception had received a diagnosis of subthreshold ADHD at the same age as sustaining the concussion.
Furthermore, patients with ADHD were significantly more likely than those without ADHD to have sustained more than one head injury.
Concussion Symptoms and Severity
Compared with the post-concussion patients who did not have ADHD, those with ADHD reported more severe headaches, balance problems, sleeping more than usual, drowsiness, sensitivity to noise, irritability, nervousness, feeling "slowed down" and difficulty concentrating. The ImPACT Total Symptom composite score was significantly higher in patients with ADHD than in those without.
Post-concussion patients with ADHD were more likely than those without ADHD to have symptoms on the adapted BC-PSI, and they were nearly four times more likely to have more than five severe symptoms.
Executive Functioning
On the BRIEF, patients with ADHD had significantly more impaired scores than those without ADHD on all but one subscale (emotional control).
Clinical Implications
Whether there is a causal relationship between ADHD and sport-related concussion can be determined only in a prospective longitudinal study. If ADHD does prove to be an antecedent risk factor for concussion, student-athletes should be screened for the disorder, as treating ADHD may help prevent concussions and mitigate complications during recovery.
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