Largest NFL study finds players nearly four times more likely to die from neurodegenerative disease
A new study of 19,824 National Football League (American football) players found neurodegenerative mortality was nearly four times higher than expected. Among players who died before 60, it was more than 12 times higher. The clearest warning, however, lies in the relationship between longer playing periods and greater risk. It underscores what Rezon has been saying for years: cumulative exposure to repeated sub-concussive head impacts in sport matters.
The largest study of NFL mortality to date has removed another excuse for delay.
This was not a small clinical sample. It was not a selection of symptomatic players or donated brains. It was a fully enumerated cohort of almost 20,000 athletes, linked with US National Death Index records.
NFL players have nearly four times the neurodegenerative mortality
Of the 1,994 players who had died during the study period, 178 had a neurodegenerative disease recorded as the underlying cause of death.
Compared with an age-, sex-, race- and calendar-year-standardised general population, NFL players experienced:
- 3.94 times the overall neurodegenerative mortality;
- 3.80 times the mortality from all-cause dementia;
- 3.88 times the mortality from Parkinson’s disease; and
- 4.55 times the mortality from amyotrophic lateral sclerosis, or ALS (the most common form of motor neurone disease) [1].
These are mortality figures. This means that they do not tell us how many former players are also currently living with neurological disease, cognitive impairment or progressive symptoms.
What these figures do tell us is something clear and final: NFL players are dying due to neurodegenerative disease at substantially higher rates than expected.
Players were less likely to die from other causes
The contrast within the results is also particularly striking. NFL players had 30% lower all-cause mortality than the comparison population. They were also less likely to die from cancer, cardiovascular disease, injury and suicide [1].
This was a population with a clear survival advantage across most major causes of death. These athletes were less likely to die overall. But there was one clear exception to this: brain disease. Their brain died before their body.
It is therefore unreasonable to dismiss the neurodegenerative finding as the result of comparing an unusually unhealthy group of former athletes with the wider population. By the measures reported in the study, the NFL cohort was surviving at higher rates. But neurodegenerative mortality moved sharply in the opposite direction.
The researchers also tested whether that apparent survival advantage could itself distort the result. Because NFL players were less likely to die from other causes, more might survive long enough to develop a neurodegenerative disease.
After accounting for this competing-risk effect, neurodegenerative mortality remained approximately three times higher [1].
Living longer did not explain away the result that neurodegeneration was disproportionately causing mortality in former NFL players.
NFL players had more than 12 times the expected rate of neurodegenerative mortality before 60
The study also identified a profound difference among players who died before the age of 60.
In this group, neurodegenerative mortality was 12.43 times higher than expected. ALS mortality was more than 15 times higher, while dementia mortality was more than seven times higher [1].
The implication of this is deeply concerning. The association was not confined to diseases emerging at the end of a normal lifespan. NFL players are dying from neurodegenerative disease at much younger ages than would be expected in the general population.
Longer careers were associated with greater risk
The most important finding is the relationship between career duration and neurodegenerative mortality. The period from starting to play in youth and progressing over the years into a professional career was linked to an increase in risk: the longer a player trained and competed, the greater the risk.
Players who competed in the NFL for five seasons or more had an 86% higher rate of neurodegenerative mortality than players whose careers lasted between one and four seasons [1].
Dementia mortality was almost twice as high in the longer-career group. Parkinson’s disease mortality was more than twice as high [1].
Career duration is not a direct measurement of the number of head impacts sustained. It cannot tell us the precise frequency, severity or rotational force characteristics of those impacts. But it is a meaningful proxy indicator of time spent exposed to repetitive sub-concussive head impacts and rotational forces.
The pattern is clear: the longer the period of exposure, the greater the risk.
Governing bodies cannot continue to treat repeated head impacts as harmless simply because they do not produce concussion symptoms. This dose-response relationship is consistent with wider research linking cumulative exposure to repeated sub-concussive head impacts with chronic traumatic encephalopathy (CTE) and other forms of neurological damage [4].
Cumulative brain injury is the risk sport must address
The damage from repeated sub-concussions is both tangible and cumulative [3].
Across training and competition from early years, players can experience hundreds or thousands of smaller-force, sub-concussive head impacts. These impacts may cause no loss of consciousness, no obvious disorientation and no symptoms. The player remains on the field. The impact is rarely recorded.
That does not make it neurologically irrelevant.
Sub-concussions transmit linear and rotational forces to the brain. Rotational motion is particularly significant because it causes the brain to rotate within the skull, producing shear strain across brain tissue. Rotational forces stretch and damage brain cells and the fine blood vessels surrounding them. They compromise the integrity of the blood-brain barrier and contribute to neuro-inflammatory processes.
A sub-concussion produces no symptoms. Repeated across training sessions, seasons and careers, however, the cumulative burden of damage to the brain accumulates and risks triggering longer-term neurodegenerative consequences.
Brain injury risk in sport is not defined by one big hit. It is shaped by the total number of small-force impacts, the rotational forces transmitted during each one, and the athlete’s cumulative lifetime exposure.
That risk begins as soon as a player is exposed to repeated head impacts, which is often in childhood when sports are first introduced.
Cumulative brain injury requires cumulative brain injury risk reduction
Sport must reduce the frequency of unnecessary head impacts. It must also reduce the rotational forces transmitted during the head impacts that remain part of training and competition.
That requires action across rules, coaching, contact loads, playing technique, enforcement, and the use of head-worn brain protection.
The objective must be to reduce exposure to the accumulated burden of sub-concussive brain injury and the triggering of longer-term neurodegenerative consequences.
This study examined professional American football, but its implications extend far beyond the NFL.
Rugby, football, hockey, lacrosse, combat sports and other contact and collision sports expose athletes to repeated concussive and sub-concussive head impacts. The specific impact profiles differ, but the central principle remains the same. Cumulative exposure over years to sub-concussive head impacts and rotational forces matters.
Every season without brain protection in sport means another season of avoidable exposure.
Why parents are choosing to protect their child’s brain in sport
Rezon Halos® is brain protection for sport.
Its purpose is to reduce the transmission of forces associated with the biomechanics of brain injury in concussive and sub-concussive head impacts, and reduce the accumulated damage from sub-concussions.
Rezon Halos® uses patented Rotection® technology and has been independently tested using Virginia Tech methodology.
Why Choose Halos®:
- reduces rotational force transmission by up to 61%;
- reduces linear force transmission by up to 64%;
- reduces concussion risk by 74%;
- achieved a Virginia Tech 5-Star safety rating;
- holds CE and UKCA Category II PPE certification;
- is the only non-helmeted head-worn protection to combine CE/UKCA Category II PPE certification with a Virginia Tech 5-Star safety rating [7].
This combination matters because the future of sports head protection is not only about padding the outside of the head. It is about protecting the brain by reducing the forces transmitted to the brain and the accumulated damage from sub-concussions.
- Neurodegenerative mortality among National Football League players. Luster CB, Abdolmohammadi B, Mastrodicasa MJ, et al. eClinicalMedicine. 2026.
- NFL players four times more likely to suffer neurodegenerative mortality. Mass General Brigham. 2026.
- Uncovering the hidden effects of repetitive subconcussive head impact exposure: a mega-analytic approach characterizing seasonal brain microstructural changes in contact and collision sports athletes. Kwiatkowski A, Weidler C, Habel U, et al. Hum Brain Mapp. 2024.
- Leveraging football accelerometer data to quantify associations between repetitive head impacts and chronic traumatic encephalopathy in males, Daneshvar DH, Nair ES, Baucom ZH, Rasch A, Abdolmohammadi B, Uretsky M, Saltiel N, Shah A, Jarnagin J, Baugh CM, Martin BM, Palmisano JN, Cherry JD, Alvarez VE, Huber BR, Weuve J, Nowinski CJ, Cantu RC, Zafonte RD, Dwyer B, Crary JF, Goldstein LE, Kowall NW, Katz DI, Stern RA, Tripodis Y, Stein TD, McClean MD, Alosco ML, McKee AC, Mez J, 2023.
- Subconcussive Head Impact Exposure and White Matter Tract Changes over a Single Season of Youth Football, Naeim Bahrami, Dev Sharma, Scott Rosenthal, Elizabeth M. Davenport, Jillian E. Urban, Benjamin Wagner, Youngkyoo Jung, Christopher G. Vaughan, Gerard A. Gioia, Joel D. Stitzel, Christopher T. Whitlow, and Joseph A. Maldjian, 2016.
- Blood-brain barrier disruption, traumatic encephalopathy, and repetitive head trauma in athletes. Greene, C. et al. Science Translational Medicine, 2026.
- Brain Protection Technology. Further Reading. Rezon.
Author: Judith McMinn
