Table 2. Sample Characteristics of the Deceased US Football Players.
| Characteristic | Patients, No. (%) |
|---|---|
| Total, No. | 180a |
| Demographic Factors | |
| Age at death, mean (SD), y | 67.9 (12.7) |
| African American | 34 (18.9) |
| Education level | |
| Less than high school or some high school | 1 (0.6) |
| High school or graduate equivalency diploma | 2 (1.1) |
| Some college | 34 (18.9) |
| College degree | 94 (52.2) |
| More than college | 10 (5.6) |
| Graduate degree | 39 (21.7) |
| Athletic participation time variables, mean (SD), y | |
| Football play | 14.9 (5.7) |
| Since retirement | 40.9 (12.7) |
| Age at first exposure to football | 12.1 (2.8) |
| Highest level played | |
| Youth or high school | 7 (3.9) |
| College | 45 (25.0) |
| Semiprofessional | 7 (3.9) |
| Professional | 121 (67.2) |
| Football primary position | |
| Lineman (offensive or defensive) | 83 (46.1) |
| Linebacker | 22 (12.2) |
| Defensive back or safety | 18 (10.0) |
| Running back | 27 (15.0) |
| Quarterback | 13 (7.2) |
| Special teams | 1 (0.6) |
| Other or multiple | 9 (5.0) |
| Wide receiver | 2 (1.1) |
| Unknown | 5 (2.8) |
| Any other contact sport history | 28 (15.6) |
| Military historyb | 53 (29.4) |
| Combat exposure | 7 (3.9) |
| Neuropathologic Factors | |
| Chronic traumatic encephalopathy | |
| I | 12 (6.7) |
| II | 23 (12.8) |
| III | 86 (47.8) |
| IV | 59 (32.8) |
| Dorsolateral frontal cortex neurofibrillary tangles density rating | |
| None | 5 (2.8) |
| Mild | 45 (25.0) |
| Moderate | 40 (22.2) |
| Severe | 90 (50.0) |
| Lewy body disease | |
| Brainstem predominant | 9 (5.0) |
| Limbic or neocortical | 29 (16.1) |
| Frontotemporal lobar degeneration | |
| Tau | 8 (4.4) |
| TDP-43 | 8 (4.4) |
| Motor neuron disease | 10 (5.6) |
| Prion disease | 2 (1.1) |
| Alzheimer disease neuropathologic changes | |
| Not Alzheimer disease | 90 (50.0) |
| Alzheimer disease neuropathologic change severity | |
| Low | 25 (13.9) |
| Intermediate | 41 (22.8) |
| High | 24 (13.3) |
| Consortium to Establish a Registry for Alzheimer Disease neuritic plaque score | |
| None | 101 (56.1) |
| Sparse | 50 (27.8) |
| Moderate | 17 (9.4) |
| Frequent | 12 (6.7) |
| Braak stage | |
| 0-III | 142 (80.2) |
| IV-VI | 35 (19.8) |
Abbreviation: TDP-43, transactive response DNA-binding protein 43 kDa.
a
Of the 180 participants, samples sizes were reduced to 179 individuals for combat history and 177 individuals for Braak stage because of missing data.
b
Military history refers to any history of service in the military, regardless of combat exposure.