Table 2.
Descriptive statistics on intentional (heading) and unintentional head impacts and neuropsychological (NP) scores by demographic and other factors using data from the 741 HeadCounts-2w and the in-person NP assessments.
| Variable | Category | Percenta (N = 741) | Heading/2-weeks | Unintentional head impacts % | Mean scores | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean | Median | International shopping list | Groton maze chase task | Identification task | One back task | Two back task | International shopping list recall | ||||
| Total | 100 | 44.9 | 15 | 36.5 | 26.7 | 1.5 | 2.7 | 1.3 | 1.2 | 9.6 | |
| Gender | Male | 77.7 | 50.2b,c | 17 | 34.0 | 26.2 | 1.6 | 2.7 | 1.3 | 1.2 | 9.4 |
| Female | 22.3 | 26.2b,c | 7 | 37.0 | 28.5 | 1.6 | 2.7 | 1.3 | 1.3 | 10.4 | |
| Age | 18–20 | 23.8 | 63.5b,c | 24.5 | 40.9 | 26.6 | 1.6 | 2.7 | 1.3 | 1.2 | 9.4 |
| 21–23 | 25.1 | 58.2b,c | 24 | 38.2 | 26.4 | 1.6 | 2.7 | 1.3 | 1.3 | 9.5 | |
| 24–28 | 24.7 | 27.2b,c | 10 | 27.3 | 27.4 | 1.6 | 2.7 | 1.3 | 1.20 | 10 | |
| 29+ | 26.5 | 32.2b,c | 13 | 32.7 | 26.6 | 1.3 | 2.7 | 1.3 | 1.2 | 9.5 | |
| Years Playing Soccer at similar frequency | 0–8.9 | 33.6 | 40.7 | 12 | 34.9 | 27.2 | 1.6 | 2.7 | 1.3 | 1.2 | 9.8 |
| 9–14.9 | 32.7 | 58.3 | 21.5 | 39.3 | 26.5 | 1.6 | 2.7 | 1.3 | 1.2 | 9.4 | |
| 15–26.9 | 26.0 | 38.5 | 15 | 29.5 | 26.6 | 1.6 | 2.7 | 1.3 | 1.2 | 9.7 | |
| 27+ | 7.7 | 27.9 | 11 | 31.6 | 26.3 | 1.3 | 2.8 | 1.3 | 1.2 | 9.3 | |
| Position played most often | Forward | 19.8 | 56.1b,c | 22 | 45.2 | 25.8 | 1.5 | 2.7 | 1.3 | 1.2 | 9.2 |
| Midfield | 37.3 | 39.9b,c | 15 | 32.7 | 26.5 | 1.6 | 2.7 | 1.3 | 1.2 | 9.4 | |
| Defense | 36 | 48.6b,c | 15 | 29.3 | 27.4 | 1.5 | 2.7 | 1.3 | 1.2 | 9.9 | |
| Goaltender | 6.9 | 22.9b,c | 6 | 45.1 | 26.9 | 1.6 | 2.7 | 1.3 | 1.2 | 9.7 | |
| Concussions (all causes): lifetime | None | 79.8 | 50.4b | 16 | 34.2 | 26.5 | 1.6 | 2.7 | 1.3 | 1.2 | 9.5 |
| 1–2 | 16.6 | 25.8b | 12 | 35.8 | 27.1 | 1.5 | 2.7 | 1.3 | 1.2 | 9.7 | |
| 3–4 | 2.0 | 15.1b | 12 | 33.3 | 29.1 | 1.6 | 2.7 | 1.4 | 1.4 | 10.9 | |
| 5–6+ | 1.6 | 5.4b | 3.5 | 50 | 29.3 | 1.2 | 2.7 | 1.5 | 1.3 | 10.3 | |
| Cigarette smoking | Never | 71.3 | 49 | 16 | 35 | 26.3 | 1.5 | 2.7 | 1.3 | 1.2 | 9.4 |
| 1+ pack/day | 28.7 | 34.8 | 13 | 33.8 | 27.7 | 1.5 | 2.7 | 1.3 | 1.3 | 10.1 | |
| Drinks of Alcohol Per Week | Never | 29.8 | 80.3b,c | 36 | 40.7 | 25.9 | 1.5 | 2.7 | 1.2 | 1.2 | 9.1 |
| 1–2 | 35.8 | 33.7b,c | 15 | 32.5 | 26.7 | 1.5 | 2.7 | 1.3 | 1.2 | 9.7 | |
| 3–7 | 26.5 | 24.1b,c | 10 | 32.1 | 27.4 | 1.6 | 2.7 | 1.3 | 1.3 | 9.8 | |
| 8+ | 7.6 | 32.3b,c | 11.5 | 32.1 | 27.8 | 1.5 | 2.7 | 1.3 | 1.3 | 10.2 | |
| WRAT Scores |
0–96.9 | 23.2 | 71.6b | 31 | 37.2 | 24.9 | 1.5 | 2.7 | 1.2 | 1.2 | 8.9 |
| 97–104.9 | 25.6 | 41.4b | 16.5 | 34.7 | 26.8 | 1.6 | 2.7 | 1.3 | 1.2 | 9.6 | |
| 105–113.9 | 26 | 41.7b | 15 | 31.6 | 26.8 | 1.6 | 2.7 | 1.3 | 1.2 | 9.6 | |
| 114+ | 25.1 | 27.1b | 9 | 35.5 | 28.3 | 1.6 | 2.7 | 1.3 | 1.3 | 10.2 | |
aPercent of total HeadCounts-2w by covariates, not individual soccer players.
bSignificant difference (p < 0.05) in mean heading by category when tested alone.
cSignificant difference (p < 0.05) in mean heading by category after adjusting for other covariates.