Cohort studies of former American football players using medical record linkage or death certificates
| Psychiatric illness | Suicide | Alzheimer’s disease or dementia | Mild cognitive impairment | Parkinson’s disease/ parkinsonism | ALS | Any neurodegenerative disease | ||||
| First author/ref | Sample | Sample size | Years played | % (n) | % (n) | % (n) | % (n) | % (n) | % (n) | % (n) |
| Janssen 45 | Former American varsity high school football | 296 | 1956–1970 | NR | NR | 0.7 (2) | 1.7 (5) | 1.0 (3) | 0 (0) | 3 (10) |
| Former high school athlete controls* | 190 | 1956–1970 | NR | NR | 0.5 (1) | 2.1 (4) | 1.6 (3) | 0 (0) | 4 (8) | |
| Savica 44 | High school football | 438 | 1946–1956 | NR | NR | 3.0 (13) | NR | 2.3 (10) | 0.5 (2) | 5.7 (25) |
| Non-athlete controls† | 140 | – | NR | NR | 1.4 (2) | NR | 3.6 (5) | 0.7 (1) | 5.7 (8) | |
| Baron 42 | Deceased former NFL players | 334 | 1959–1988 | 1.2 (4) | 2.7 (9) | NR | NR | NR | NR | 3.6 (12)‡ |
| Men in general population | – | – | 3.5 (11.7) | 6.5 (21.8) | NR | NR | NR | NR | 2.9 (9.7) | |
| Lehman 43 | Deceased former NFL players | 334 | 1959–1988 | NR | NR | 2.1 (7) | NR | 0.9 (3) | 2.1 (7) | 5.1 (17) |
| Men in general population | – | – | NR | NR | NR | NR | NR | NR | NR | |
| Lehman 41 | Deceased former NFL players | 537 | 1959–1988 | NR | 2.2 (12) | NR | NR | NR | NR | NR |
| Men in general population | – | – | NR | 4.8 (25.6) | NR | NR | NR | NR | NR |
The two studies of high school football players are medical record linkage studies and illustrate the rates of diagnoses present in those records. The three studies of former NFL players are based on reviewing death certificates and address underlying or contributing causes of death. There were 3439 former NFL players, of whom 334 died between 1960 and 200742 ,43, and 537 died between 1960 and 2013.41 The differing methodologies do not allow a direct comparison between high school and former NFL athletes. *Controls were non-football-playing male varsity athletes, such as swimmers, wrestlers and basketball players.
†Controls were non-football-playing male students in the glee club, band or choir.
‡Defined by Baron et al as any disease of nervous system and sense organs. From Baron et al 42: mental, psychoneurotic and personality disorders=4 (expected=11.7; standardised mortality ratio (SMR)=0.34, 95% CI 0.09 to 0.87). Intentional self-harm=9 (expected=21.8, SMR=0.41, 95% CI 0.19 to 0.78). Diseases of the nervous system and sense organs=12 (expected=9.7; SMR=1.24, 95% CI 0.64 to 2.16). For Lehman et al 43 , the number of times neurodegenerative diseases were listed as an underlying or contributing cause of death is reported. From Lehman et al 41 : suicide=12 (expected=25.6, SMR=0.47, 95% CI 0.24 to 0.82).
ALS, amyotrophic lateral sclerosis; n, frequency; NR, not report.