Attention-Deficit/Hyperactivity Disorder and Outcome After Concussion: A Systematic Review

Objective: To synthesize the literature and conduct a gap analysis on the association between attention-deficit/hyperactivity disorder (ADHD) and clinical outcome from sport-related concussion. Method: The electronic search for this systematic review (PROSPERO ID: CRD42019128281) was conducted in February 2019 using terms related to concussion, sports/athletics, and predictors/modifiers of outcome to search the PubMed, PsycINFO, MEDLINE, CINAHL, Cochrane Library, EMBASE, SPORTDiscus, Scopus, and Web of Science databases. Eligible studies evaluated the association between ADHD and outcome from sport-related concussion. Of 4014 studies screened, 359 full-text articles were reviewed, with 14 studies ultimately included, involving 3623 participants (n = 359 [9.9%] with ADHD). Results: Study samples were primarily from specialty medical clinics (57.1%) and high school or college athletic groups (28.6%). Only 2 studies reported a statistically significant association between ADHD and worse clinical outcome. Of these, 1 included 13 participants with ADHD and the other included only 8 participants with ADHD. Only 1 previous study in this review was designed specifically to examine ADHD and prolonged concussion recovery, and that study did not report a statistically significant association. Conclusion: There is not a clear association between ADHD and worse clinical outcome from concussion. However, eligible studies had limitations in research design, and nearly all studies were underpowered and evaluated the association between ADHD and concussion outcome as a secondary focus rather than the primary research question, precluding definitive conclusions. The association between ADHD and clinical outcomes remains unclear, and future research specifically examining ADHD and concussion recovery is needed.