The relationship between brain atrophy and cognitive-behavioural symptoms in retired Canadian football players with multiple concussions

Abstract

Multiple concussions, particularly in contact sports, have been associated with cognitive deficits, psychiatric impairment and neurodegenerative diseases like chronic traumatic encephalopathy. We used volumetric and deformation-based morphometric analyses to test the hypothesis that repeated concussions may be associated with smaller regional brain volumes, poorer cognitive performance and behavioural symptoms among former professional football players compared to healthy controls. This study included fifty-three retired Canadian Football League players, 25 age- and education-matched healthy controls, and controls from the Cambridge Centre for Aging and Neuroscience database for validation. Volumetric analyses revealed greater hippocampal atrophy than expected for age in former athletes with multiple concussions than controls and smaller left hippocampal volume was associated with poorer verbal memory performance in the former athletes. Deformation-based morphometry confirmed smaller bilateral hippocampal volume that was associated with poorer verbal memory performance in athletes. Repeated concussions may lead to greater regional atrophy than expected for age.

Keywords: Aging; Deformation based morphometry; Mild traumatic brain injury; Sport-related concussion.

Fig. 1

Linear regression model results showing the relationship between left and right hippocampal volumes and age in ex-CFL players, study controls and Cam-CAN controls. Modelling of age and left and right hippocampal volumes show a much steeper effect of age on hippocampal volumes in the former CFL players compared to both study controls and Cam-CAN controls. Dots represent the data points for each subject, and lines represent the linear regression model estimates for these data points.

Fig. 2

Pearson correlation graphs in ex-CFL and controls between left and right hippocampal volumes and the RAVLT short delay total score, the RAVLT long delay total score and the RVDLT long delay total score. Significant relationships were found between left and right hippocampal (HC) volumes and RAVLT short and long delay scores in the ex-CFL but not in the study controls.

Fig. 3

Deformation-based morphometry showing regions associated with RAVLT short delay scores in ex-CFL players. FDR (q = 0.05) corrected p value map for regions associated with RAVLT short delay scores in ex-CFL players. Colours represent p-values and indicate the left medial temporal lobe, including primarily the hippocampus, parahippocampus, and entorhinal cortex.