Abstract:
Objective: There is concern that sustaining multiple concussions will result in cumulative negative effects on neurocognition. However, the existing literature is mixed, primarily adult focused, and there is no clear answer for patients, clinicians, researchers, or policy makers. The purpose of this study was to examine whether there are cumulative effects with objective and subjective abilities from concussions in adolescents. Methods: Participants included 751 top tier hockey players between 12 and 17 years (mean age ¼ 15.0, SD ¼ 1.2) in Alberta, Canada, who reported on a previously validated pre-season questionnaire to have had zero (n ¼ 371), one (n ¼ 172), and two or more (n ¼ 43) past concussions. Players with self-reported attention (n ¼ 23) or learning (n ¼ 2) disorders, a concussion within 3 months of baseline testing (n ¼ 27), missing pre-season information (n ¼ 76), as well as those with suspected invalid test profiles (n ¼ 37) were excluded. Baseline testing included ImPACT. Age- and gender-adjusted composite percentile scores were examined. Results: Those with one prior concussion had worse visual memory than those with zero concussions (Mann–Whitney U ¼ 2.52, p ¼ .012, Cohen’s effect size d ¼ 0.23) and those with two or more prior concussions (U ¼ 2.91, p ¼ .004, d ¼ 0.51). No differences in self-reported symptoms were found between zero and one concussion (U ¼ 1.48, p ¼ .14, d ¼ 0.16), but there were significantly more symptoms in those with two or more prior concussions compared with those with zero (U ¼ 3.54, p , .001, d ¼ 0.82) or one (U ¼ 2.58, p ¼ .010, d ¼ 0.57) prior concussion. Conclusions: There is a small effect of having one, but not two or more, previous concussions only on visual memory (no other cognitive domains). Increased self-reported symptoms were found with two or more prior concussions.