CTE in 2018: Understanding Football Brain Damage in 5 Charts

By Charles Li MD

  • For decades, we thought getting your head hit in the field was mostly harmless, e.g. "Getting your bell rung"
  • It turns out, for professional football players, these hits may be causing brain damage.
  • Because the symptoms can take years or decades to show up, we haven't begun studying the full extent of this damage, termed CTE, until recently.

Dementia in Retired NFL Players

  • We've known for years that retired NFL players have a higher risk of dementia, including Alzheimer's Disease.
  • A 2012 study of 3,439 retired NFL players found that while they had a lower death rates than the average American man:
Total Mortality
  • They were much more likely to die from neurodegenerative disease (All ND), including Alzheimers (Dementia/AD) and ALS:
Relative rates of neurodegenerative disease for Retired NFL players vs Average Men
All ND

Neurodegenerative Disease by Position

  • Players at risk of getting tackled at high speeds repetitively were even more likely to get these diseases than other players.
  • "Speed Players" include Fullbacks, Halfbacks, Defensive Backs, Quarterbacks, and other positions at risk of high speed impact.
Relative rates of neurodegenerative disease for Speed players vs Linemen
ND by Position

The Cause: Long Term Brain Damage

  • A recent study from 2018 has shown that this is likely far more widespread than we had previously believed
  • Out of 111 NFL players who donated their brains to research, 110 were found to have brain damage.
  • CTE was also found in former college players, semipro players, and even former high school players.
Percent of Patients Studied with CTE

Most Common Symptoms of CTE

  • 111 CTE patients from the same study also reported on their symptoms. Nearly all patients had significant neurological and/or psychological symptoms.
  • These data shed light on the symptoms associated with CTE brain damage.
  • 86% of patients reported that their symptoms got worse over time.
  • However, these were a self-selected group of individuals, as more symptomatic individuals may be more likely to have donated.
Most Common Symptoms in Patients with CTE

Cognitive Symptoms



Motor Difficulties

CTE in High School Football

  • Fortunately, the vast majority of high school football players appear to be just fine.
  • 296 Varsity Football players who had played from 1956-1970 were studied by the Mayo Clinic, and compared to 190 athletes from other sports.
  • Despite having more medically documented head trauma (e.g. hits to the head on the field), there was no significant increase in neurodegenerative disease detected.
  • The chart below shows the estimated relative rates of diagnoses between football players and other athletes.
  • The bars represent the confidence intervals (margins of error), blue bars represent no significant differences.
Neurodegenerative Disease in Former High School Football Players
More Visualizations to Explore:


1) Lehman EJ, Hein MJ, Baron SL, Gersic CM. Neurodegenerative causes of death among retired National Football League players. Neurology. 2012;79(19):1970-1974. doi:10.1212/WNL.0b013e31826daf50.

2) Mez J, Daneshvar DH, Kiernan PT, et al. Clinicopathological Evaluation of Chronic Traumatic Encephalopathy in Players of American Football. JAMA. 2017;318(4):360–370. doi:10.1001/jama.2017.8334

3) Janssen PH, Mandrekar J, Mielke MM, et al. High-school football and late-life risk of neurodegenerative syndromes, 1956–1970. Mayo Clinic proceedings. 2017;92(1):66-71. doi:10.1016/j.mayocp.2016.09.004.