BMJ (Clinical research ed.)
Prevalence of chronic traumatic encephalopathy at death in National Football League players: retrospective population based cohort study, 2008-21
Study Type: Retrospective population-based cohort study
Key Question: What is the plausible prevalence of chronic traumatic encephalopathy (CTE) among deceased former NFL players, and how does CTE severity relate to dementia risk?
Key Findings:
- Among all 1712 deceased NFL players (2008-21), possible CTE prevalence ranged widely (18.5%–98.7%); during 2016-21 (peak donation period), the range narrowed to 24.5%–97.7%, suggesting a true minimum of roughly one-quarter.
- Among 338 brain donors, 93.2% had CTE and 30.8% had stage IV disease; stage IV CTE was associated with a 44% higher risk of clinician-diagnosed dementia (RR 1.44, 95% CI 1.16–1.78, p<0.001).
- Neurodegenerative disease was recorded as cause of death in only 18.6% of donors and in just 40.6% of those with confirmed dementia, indicating substantial under-recognition on death certificates.
Clinical Relevance: Highlights that repetitive head impact-related neurodegeneration is likely underdiagnosed and under-certified, reinforcing the need for GPs to consider CTE/dementia risk when assessing cognitive symptoms in patients with significant contact-sport histories (relevant to UK rugby/football concussion pathways).
Limitations: Selection bias is substantial, as brain donation was voluntary and likely over-represents symptomatic players, limiting generalisability of prevalence estimates.
