The Long-Term Effects of Sport-related Concussions on Cognition in Interscholastic and Collegiate Athletes: A Meta-analysis of Cross-Sectional Studies

Background Over the past twenty years researchers have conducted cross sectional and longitudinal studies to examine how concussions could impact cognitive functions. Previous meta-analysis exploring the effect of a sport-related concussion on cognition lacked matched control groups and only assessed short-term effects ranging 7-14 days. There is increasing evidence and interest in examining the long term cognitive effects of concussions spanning over several weeks to months following the injury. Objective The purpose of this meta-analysis was to synthesize this concussion-cognition literature and determine the long term effects of concussion spanning 7 days up to 1 year post-injury. Methods A literature search was conducted to locate published cross-sectional studies on concussion and cognition in interscholastic and intercollegiate athletes. A total of eight studies published between August 2006 and May 2017 were included encompassing 915 athletes from 17 different sports. Neuropsychological assessments were conducted with these athletes after 7 days up to a year. Results We found 8 studies examining the effects of concussions on cognition in athletes. Using the CMA software the overall effect of concussion on cognition was significant when compared to athletes without a history of concussions (g = -0.413, p < 0.014). More specifically of the three cognitive domains, executive function (g = -0.645, p < 0.033) and attention and processing speed (g = -0.429, p < 0.006) showed significant effect sizes while memory (g = -0.314, p < 0.128) was not significant. Conclusion Our findings suggest that concussions not only have an acute negative impact on cognitive functions, but these effects can last up to a year post-injury affecting the executive function, attention and processing speed domains. We discuss the limitations of studies and implications for future research.