A Recent Study

A study in The BMJ by Daneshvar and colleagues identified 1,712 former NFL players who died between 2008 and 2021. Of the 338 who underwent neuropathological examination, 315 (93.2%) had chronic traumatic encephalopathy (CTE). However, that percentage cannot be interpreted as the prevalence among all former NFL players. Families of players with cognitive, behavioral, or neurological problems may be more likely to donate their brains, potentially inflating donor-based estimates. Conversely, counting only confirmed cases among all deceased players misses disease in unexamined brains. The true population prevalence therefore remains uncertain.¹

The Number That Deserves Our Attention

Consider the 2016 to 2021 period. Approximately one in four documented former NFL players who died during this period had neuropathologically confirmed CTE. The 24.5% figure represents a minimum observed prevalence, because additional cases may have been present among players whose brains were not examined.¹

New Evidence Addressing Selection Bias

Gallini and colleagues addressed this uncertainty in a 2026 JAMA Network Open study of 2,362 former NFL players who died between 2008 and 2023. Among 387 brain donors evaluated for CTE, 362 (93.5%) had the neuropathology. After modeling differences in brain donation associated with cognitive symptoms, the estimated prevalence among all deceased players was 74.5% (95% confidence interval, 69.6%–78.3%); a conservative sensitivity analysis yielded 63.7%.

The authors concluded that selection bias inflates donor-based estimates but is unlikely to fully explain the substantial burden of CTE neuropathology. These are model-based estimates dependent on assumptions about cognitive symptoms and donation patterns, rather than confirmation in every player. They apply to deceased NFL players and should not be extrapolated to living players, less-exposed athletes, or our general patient population. Furthermore, CTE neuropathology does not necessarily indicate symptomatic disease or dementia.²

Why This Matters in Our Offices

Chiropractors regularly evaluate patients who have sustained head and neck trauma. Many present with headaches, neck pain, dizziness, balance problems, cognitive complaints, sleep disturbances, and persistent symptoms. These complaints warrant careful assessment because they may reflect overlapping neurological, vestibular, musculoskeletal, or other conditions. The NFL studies do not establish the prevalence of CTE or brain injury among patients presenting to chiropractic offices.

I previously wrote a PostGradDC Clinical Pearl, “Imaging Traumatic Brain Injury,” discussing diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT). These techniques are relevant to research on white matter injury, but their potential should not be confused with an established ability to diagnose CTE in an individual patient. Imaging and biomarker testing should be selected for a specific clinical indication. The American College of Radiology offer imaging appropriateness criteria for traumatic brain injury.³

We Need to Ask Better Questions

For years we asked, “How many concussions have you had?” That question is no longer enough. Consider asking:

• What sports did you play?
• For how many years?
• What position?
• Have you had diagnosed concussions or other traumatic brain injuries?
• What about repetitive head impacts that were never diagnosed as concussions?
• Have your symptoms persisted, progressed, or affected work and daily activities?
• What neurological assessments, imaging, or other testing have you undergone, and what did they show?

What We Can Do, and What We Can’t

Our job is not to diagnose CTE. It remains a neuropathological diagnosis that can currently be confirmed only after death. However, it is vital to conduct careful histories and examinations. We must understand the indications and limitations of neurological assessments, imaging, and biomarkers, and use appropriate referral pathways to investigate persistent or progressive symptoms.

Our Job Is to Recognize, Evaluate, Differentiate, Treat, and Refer When Appropriate

• Don’t dismiss. When a patient with a head injury history presents with progressive cognitive changes, balance problems, behavioral changes, persistent headaches, dizziness, sleep disturbances, or neurological abnormalities, don’t simply attribute the findings to aging, cervical dysfunction, or an old concussion.
• Examine carefully. Assess cognition, gait, balance, coordination, cranial nerves, sensory function, and motor function.
• Build a real differential. Consider neurodegenerative disease, cerebrovascular disease, vestibular disorders, metabolic abnormalities, medications, structural pathology, and other causes.
• Escalate when appropriate. Obtain clinically indicated imaging or refer to neurology, neuropsychology, neuroradiology, vestibular specialists, or other qualified providers. Acute or rapidly worsening neurological findings require urgent evaluation.
• Keep helping. Manage appropriate musculoskeletal, cervicogenic, headache, and functional complaints within our scope, while staying alert to findings that require further investigation.

Final Thoughts

Chiropractic physicians are often sought out by patients with symptoms following head and neck trauma. Our training supports the evaluation and management of associated neuromusculoskeletal conditions within our scope of practice. Continuing education helps us recognize emerging evidence, understand the limitations of available tests, and coordinate appropriate care to improve patient outcomes.

References

1. Daneshvar DH, et al. Prevalence of chronic traumatic encephalopathy at death in National Football League players: retrospective population based cohort study, 2008-21. BMJ. 2026;394. doi:10.1136/bmj-2026-100418.
2. Gallini J, Alosco ML, Abdolmohammadi B, et al. Bias-adjusted prevalence of chronic traumatic encephalopathy among deceased National Football League players. JAMA Network Open. 2026;9(10). doi:10.1001/jamanetworkopen.2026.40884.
3. ACR Criteria. https://acsearch.acr.org/docs/69481/Narrative/

PostGradDC offers advanced postgraduate chiropractic continuing education. Our founder, Dr. James Demetrious, is a distinguished board-certified chiropractic orthopedist, educator, author, and editor.

© 2026 James Demetrious, DC, DABCO. Open Access. Unrestricted use, distribution, and reproduction are allowed in any medium, provided appropriate credit is given by citing the original author and source: Demetrious J. Former NFL Players, CTE, and the Questions We Should Be Asking. PostGradDC.com; 2026.