OBJECTIVE: Determine whether repetitive hits to the head at a subclinical level are associated with structural and functional brain abnormalities and if these effects are influenced by high levels of fitness associated with intense physical activity.
METHODS: Seventy-two college students were recruited: 24 non-athletes, 24 athletes practicing a varsity contact sport, and 24 athletes practicing a varsity non-contact sport. They were recruited for a neuropsychological evaluation and a magnetic resonance imaging session that included magnetic resonance spectroscopy of primary motor cortex (M1) and prefrontal cortex and susceptibility-weighted imaging.
RESULTS: There was no evidence for reduced cognitive performance or presence of microbleeds in contact sports athletes. Abnormalities in contact sports athletes were found for myo-inositol concentration (mIns) in M1, where levels were significantly higher compared to non-contact sports athletes (p = 0.016) and non-athletes (p = 0.029). In prefrontal cortex, glutamate+glutamine (Glx) was significantly reduced in contact sports athletes compared to non-contact sports athletes (p = 0.016) and a similar reduction was observed for gamma-Aminobutyric acid (GABA) levels (p = 0.005).
CONCLUSION: Varsity contact sports are associated with area-specific alterations in mINS concentration in primary motor cortex. In prefrontal cortex, high levels of fitness could modulate the effects of head impact exposure on prefrontal metabolite concentration. Indeed, although contact- and non-contact sports athletes show different neurometabolic profiles, they do not differ from sedentary controls.