In‐season docosahexaenoic acid supplementation does not prevent white matter damage during a single American football season: Implications for neurodegeneration prevention

Background Repetitive sub‐concussive head impacts (RSHIs) are common in American football, result in changes to white matter microstructural integrity, and are suggested as a potential risk factor for neurodegenerative diseases, including Alzheimer’s disease. RSHI‐induced white matter degradation may accelerate neurodegenerative processes, necessitating effective preventative and therapeutic approaches in this population. Prior studies indicate potential neuroprotective and remyelinating effects of docosahexaenoic acid (DHA). Here, we conducted a double‐blind, randomized, placebo‐controlled trial to assess the effects DHA supplementation during a National Collegiate Athletic Association football season on neuroimaging measures of white matter integrity. Method Thirty‐eight participants were randomized to treatment (6g DHA/EPA) or placebo (6g oleic/linoleic acid) group for seven months of five‐times‐per‐week supplementation. 27 participants completed the trial and had complete neuroimaging datasets ( n = 16 placebo; n = 11 treatment). White matter integrity changes from preseason to immediately post‐season were quantified using voxel‐wise fractional anisotropy and diffusivity (mean, axial, radial) as well as deterministic tractography using quantitative anisotropy (QA). Gray matter volume as well as intra‐regional, edge‐wise, and network level functional connectivity were obtained as secondary measures along with serum neurofilament light (NfL) as a peripheral biomarker of axonal damage. Result There were no voxel‐wise, between‐group differences in voxel‐wise DTI analyses. Compared to placebo, the treatment group had increased QA in ascending corticostriatal fibers and decreased QA in long association and commissural fibers. Increased mean (ρ = 0.47), axial (ρ = 0.44), and radial (ρ = 0.51) diffusivity and decreased QA (ρ = ‐0.52) in the corpus callosum and bilateral corona radiata were correlated with increasing NfL levels during the season irrespective of treatment group. Default mode/frontoparietal network connectivity ( g = 0.96, p = 0.024) was greater in the treatment group. Conclusion In‐season DHA supplementation was insufficient to prevent or protect against axonal damage as it occurred during the season. However, there may be neuroprotective effects on functional connectivity despite structural damage. If RSHIs are a risk factor for future neurodegeneration, then alternative therapeutic merit further investigation. These present outcomes do not support the use of in‐season DHA supplementation as a preventive strategy to reduce brain injury resulting from collegiate football. Acknowledgement Study funded by the Center for Innovation in Brain Science, University of Arizona. DHA provided by Pharmavite