Spatial working memory performance following acute sport-related concussion

Abstract

Introduction An important problem in the field of sport-related concussion is the lack of a ‘gold-standard’ clinical assessment tool. Currently, the diagnosis relies heavily on self-reporting of symptoms and observation of clinical signs by medical professionals. To address this, our group has been motivated to develop objective measures of neurological impairment following concussion. Spatial working memory is an important aspect of cognitive function that might be impaired following concussion. In the present study, we measured spatial working memory using a robotic spatial span task. We first assessed test–retest reliability in 82 healthy athletes who underwent baseline testing across two athletic seasons using intraclass correlation coefficients. We then assessed spatial span performance relative to baseline in 47 athletes acutely following sport-related concussion using a reliable change index with 80% confidence limits to define impairment on an individual basis. Results We found good test–retest reliability for the mean span (a measure of spatial working memory span length; intraclass correlation coefficient = 0.79), and moderate reliability for the response duration (time taken per spatial target; intraclass correlation coefficient = 0.64) in healthy athletes. However, only 19% of acutely concussed athletes showed evidence of impairment relative to baseline in mean span, and even fewer (9%) showed evidence of impairment in response duration. Analysis of serial position curves revealed primacy and recency effects for this task, but no group-level differences between concussed and healthy athletes. Analysis of specific types of errors showed a higher rate of substitution errors in the concussed group at baseline, suggesting possible malingering in a small number of athletes. Conclusion Overall, few athletes showed evidence of impaired spatial working memory acutely following concussion, suggesting either that spatial working memory is not commonly impaired acutely post-concussion, or that the present task is not sufficiently demanding.