The study of epigenetic clocks in former professional contact sports athletes with repetitive head impacts

BACKGROUND: Repetitive head impacts in former contact sport athletes are associated with cognitive impairment, accelerated cerebral atrophy and risk of neurodegenerative disease. Epigenetic clocks derived from age-associated DNA methylation (DNAm) profiles may capture accelerated biological ageing in neurodegenerative conditions; however, their application in former athletes remains unexplored. Here we aim to explore the application of epigenetic clocks as a measure of accelerated biological ageing in a cohort of former athletes. METHODS: In 126 former athletes (96% male; mean age: 54.5±14.4 years; mean concussions: 6.8±6.7), we examined associations of brain volumes, plasma neurofilament light levels and cognitive/behavioural scores with DNAmAge-acceleration, AgeAccelResidual and DNAmFitAge-acceleration. RESULTS: We only found an association between the number of concussions and DNAmFitAge-acceleration (p=0.003, B=0.46, R²=0.063), indicating that every two additional concussions were associated with a 5-year increase in DNAmFitAge-acceleration. There was also a trend towards an association between years of play and DNAmAge-acceleration in older athletes. CONCLUSIONS: These preliminary findings suggest that specific epigenetic clock measures may serve as early markers of biological ageing related to repetitive head impacts.