Summary of findings from studies of former professional American football players
| Study | Country | N | Group | Age | Exposure | Topic/Outcome | Significant findings/risk |
| Kerr et al94 | USA | 2001 cohort=3729 of which 2536 completed the survey; 1044 with complete data in 2010 | Football (NFL) | NR | Concussions | Between 2001 and 2010, 10.2% reported a diagnosis of depression. Greater concussion history associated with greater risk for depression (eg, 3.0% in those with no prior concussions and 26.8% in those with 10+ prior concussions). | Yes/Greater |
| Brett et al114 | USA | 2001 cohort=3729 of which 2536 completed the survey; 333 had results in 2019 | Football (NFL) | Age in 2001: M=48.95, SD=9.37; Approx. average age in 2019=67 | Self-reported concussions and years of participation | Depression not greater than general population. Physical functioning rated worse than general population and decline in physical function associated with depression. Symptoms of depression associated with greater concussion history, but not years of participation. | Yes/Greater |
| Daneshvar et al115 | USA | 19 423; 38 ALS cases | Football (NFL) | Cohort range=23–78 ALS age of diagnosis M=51.0, SD=13.8 | Sports participation | ALS more common in former NFL players than general population and associated with a longer career. | Yes/Greater |
| Kmush et al116 | USA | 14 366; 763 deaths | Football (NFL) | Age at death: M=53.3, SD=14.6 | Repetitive head impacts derived from playing position and career duration | Repetitive head impacts (ie, player position) associated with greater all-cause mortality. | Yes/Greater |
| Nguyen et al117 | USA | NFL=3419, 517 deaths; MLB=2708, 431 deaths | Football (NFL) | Age at death: NFL M=59.6, SD=13.2; MLB M=66.7, SD=12.3 | Sports participation | Former NFL players had greater neurodegenerative disease mortality (7.5% of former NFL players (39/517) and 3.7% of former MLB players (16/431). Suicide was not significantly greater in former NFL players (11/517; 2.1%) compared with former MLB players (5/431; 1.2%). | Yes/Greater |
| Baron et al126 | USA | 3439, 334 deaths | Football (NFL) | At death: Md=54, Range=27–81 | Sports participation | Lower risk of mortality from mental disorders and suicide in former NFL players compared with men in the general population. No difference in diseases of the nervous system and sense organs. | No Yes/Lesser |
| Lincoln et al127 | USA | 9778; 227 deaths | Football (NFL) | At death: Md=38, Range=23–61 | Sports participation | Lower risk of mortality from mental disorders and suicide in retired NFL players; No difference in diseases of the nervous system and sense organs. | No Yes/Lesser |
| Lehman et al118 | USA | 3439; 537 deaths | Football (NFL) | NR | Sports participation | Former NFL players less likely to have suicide as manner of death than men from the general population. | Yes/Lesser |
| Lehman et al119 | USA | 3439; 334 deaths | Football (NFL) | Md=54 at death | Sports participation | Neurodegenerative disease mortality (17/334 deaths, 5.1%), primarily dementia and ALS, greater in former NFL players than the general population. | Yes/Greater |
ALS, amyotrophic lateral sclerosis; M, mean; MCI, mild cognitive impairment; Md, median; MLB, Major League Baseball; NA, not available; NFL, National Football League; NR, not reported.