Table 3.
GEE model estimating the mean difference in NP test scores by heading exposure quartiles and by number of unintentional head impacts reported in a 2-week recall period.
| Exposure | Median value | Mean difference in Neuropsychological Test Score | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Includes all 2-week episodes | Excludes episodes with reported probable or certain concussion | ||||||||
| Na | Aa mean difference (95% CI) | Wald chi-square (p-value) | Bb mean difference (95% CI) | Wald chi-square (p-value) | Na | CB mean difference (95% CI) | Wald chi-square (p-value) | ||
| N = 741 | Verbal learning: higher score = better performancec International shopping list—immediate recall (ISL) |
N = 719 | |||||||
| Heading | 2 | 177 | – | 4.20 (0.24) | – | 3.11 (0.37) | 173 | – | 3.49 (0.32) |
| 9 | 191 | 0.34 (−0.40, 1.07) | 0.35 (−0.39, 1.10) | 186 | 0.36 (−0.39, 1.10) | ||||
| 25 | 187 | −0.29 (−1.15, 0.57) | −0.22 (−1.10, 0.67) | 181 | −0.27 (−1.16, 0.63) | ||||
| 101 | 186 | −0.54 (−1.49, 0.42) | −0.40 (−1.44, 0.64) | 179 | −0.43 (−1.47, 0.61) | ||||
| Unintentional head impacts | 0 | 484 | – | 2.38 (0.31) | – | 1.30 (0.52) | 472 | – | 1.50 (0.47) |
| 1 | 140 | −0.08 (−0.82, 0.65) | −0.02 (−0.79, 0.75) | 135 | −0.05 (−0.83, 0.74) | ||||
| 2 + | 117 | −0.73 (−1.67, 0.21) | −0.56 (−1.58, 0.46) | 112 | −0.62 (−1.65, 0.42) | ||||
| N = 735 |
Psychomotor speed: higher score = better performanced Groton Maze Chase Task |
N = 713 | |||||||
| Heading | 2 | 174 | – | 24.50 | – | 22.90 | 170 | – | 23.30 |
| 9 | 191 | 0.07 (0.00, 0.15) | (0.00) | 0.08 (0.01, 0.15) | (0.00) | 186 | 0.08 (0.01, 0.16) | (0.00) | |
| 25 | 186 | −0.01 (−0.09, 0.08) | −0.00 (−0.09, 0.10) | 180 | −0.01 (−0.08, 0.10) | ||||
| 101 | 184 | −0.12 (−0.21, −0.03) | −0.11 (−0.20, −0.01) | 177 | −0.10 (−0.20, −0.00) | ||||
| Unintentional head impacts | 0 | 480 | – | 4.08 (0.13) | – | 1.77 (0.41) | 468 | – | 1.85 |
| 1 | 138 | −0.07 (−0.15, 0.01) | −0.05 (−0.12, 0.03) | 133 | −0.06 (−0.13, 0.02) | (0.40) | |||
| 2+ | 117 | −0.08 (−0.18, 0.02) | −0.05 (−0.15, 0.06) | 112 | −0.03 (−0.13, 0.08) | ||||
| N = 732 |
Attention: lower score = better performancee Identification task (IDN) |
N = 711 | |||||||
| Heading | 2 | 176 | – | 6.00 (0.11) | – | 2.54 (0.47) | 172 | – | 3.29 |
| 9 | 189 | −0.01 (−0.02, 0.01) | −0.00 (−0.02, 0.02) | 184 | 0.00 (−0.02, 0.02) | (0.35) | |||
| 25 | 185 | 0.00 (−0.2, 0.02) | 0.00 (−0.02, 0.02) | 179 | 0.00 (−0.02, 0.02) | ||||
| 101 | 182 | 0.02 (−0.01, 0.04) | 0.01 (−0.01, 0.04) | 176 | 0.02 (−0.01, 0.04) | ||||
| Unintentional head impacts | 0 | 479 | – | 0.95 (0.62) | – | 1.53 (0.47) | 468 | – | 2.10 |
| 1 | 136 | 0.00 (−0.02, 0.02) | −0.01 (−0.03, 0.01) | 131 | −0.01 (−0.03, 0.01) | (0.35) | |||
| 2+ | 117 | −0.01 (−0.04, 0.01) | −0.01 (−0.03, 0.01) | 112 | −0.02 (−0.04, 0.01) | ||||
| N = 705 |
Attention: higher score = better performancef One back task (ONB) |
N = 684 | |||||||
| Heading | 2 | 170 | – | 11.80 | – | 9.94 (0.02) | 166 | – | 9.64 |
| 9 | 176 | 0.01 (−0.03, 0.05) | (0.01) | 0.01 (−0.03, 0.06) | 171 | −0.01 (−0.03, 0.06) | (0.02) | ||
| 25 | 178 | −0.04 (−0.09, 0.01) | −0.04 (−0.09, 0.01) | 172 | −0.04 (−0.09, 0.10) | ||||
| 101 | 181 | −0.07 (−0.12, −0.01) | −0.06 (−0.12, 0.00) | 175 | −0.06 (−0.12, 0.00) | ||||
| Unintentional head impacts | 0 | 459 | – | 3.89 (0.14) | – | 1.60 (0.45) | 447 | – | 1.78 |
| 1 | 133 | −0.04 (−0.08, 0.01) | −0.03 (−0.07, 0.02) | 128 | −0.03 (−0.08, 0.02) | (0.41) | |||
| 2+ | 113 | −0.03 (−0.08, 0.01) | −0.02 (−0.07, 0.03) | 109 | −0.02 (−0.07, 0.03) | ||||
| N = 741 |
Working memory: higher score = better performanceg Two back task (TWOB) |
N = 719 | |||||||
| Heading | 2 | 177 | – | 8.77 (0.03) | – | 7.46 (0.06) | 173 | – | 7.85 |
| 9 | 191 | 0.01 (−0.03, 0.04) | 0.08 (−0.03, 0.05) | 186 | −0.01 (−0.03, 0.05) | (0.05) | |||
| 25 | 187 | −0.04 (−0.09, 0.01) | −0.09 (−0.16, −0.01) | 181 | −0.04 (−0.09, 0.01) | ||||
| 101 | 186 | −0.07 (−0.13, −0.01) | −0.03 (−0.08, 0.02) | 179 | −0.07 (−0.13, −0.00) | ||||
| Unintentional head impacts | 0 | 484 | – | 3.17 (0.21) | – | 1.26 (0.53) | 472 | – | 1.40 |
| 1 | 140 | −0.40 (−0.09, 0.01) | −0.03 (−0.08, 0.02) | 135 | −0.03 (−0.08, 0.02) | (0.50) | |||
| 2+ | 117 | −0.03 (−0.08, 0.02) | −0.01 (−0.06, 0.04) | 173 | −0.01 (−0.06, 0.04) | ||||
| N = 741 |
Verbal memory: higher score = better performanceh International shopping list delayed recall (ISRL) |
N = 719 | |||||||
| Heading | 2 | 177 | – | 2.22 (0.53) | – | 2.03 (0.57) | 173 | – | 1.88 |
| 9 | 191 | 0.18 (−0.18, 0.54) | 0.19 (−0.17, 0.55) | 186 | 0.18 (−0.19, 0.55) | (0.60) | |||
| 25 | 187 | −0.06 (−0.46, 0.33) | −0.05 (−0.45, 0.35) | 181 | −0.06 (−0.47, 0.35) | ||||
| 101 | 186 | −0.09 (−0.52, 0.35) | −0.07 (−0.54, 0.40) | 179 | −0.06 (−0.53, 0.41) | ||||
| Unintentional head impacts | 0 | 484 | – | 0.24 (0.89) | – | 0.08 (0.96) | 472 | – | 0.16 |
| 1 | 140 | −0.04 (−0.37, 0.29) | −0.03 (−0.36, 0.31) | 135 | −0.05 (−0.40, 0.29) | (0.92) | |||
| 2+ | 117 | −0.12 (−0.54, 0.32) | −0.06 (−0.52, 0.40) | 173 | −0.08 (−0.55, 0.38) | ||||
aSeparate models were run for heading and for unintentional head impacts; N refers to the number of HeadCounts-2w used in the specific model 2.
bA single model was run that included both heading and unintentional head impacts.
cCovariates: gender, main position of soccer play, WRAT; and cigarette use.
dCovariates: age and WRAT.
eCovariates: gender, main position of soccer play, age and the WRAT.
fCovariates: main position of soccer play, cigarette use, and WRAT.
gCovariates: cigarette use and WRAT and unintended model added gender.
hCovariates: gender, cigarette use, WRAT, and amount of alcoholic drinks/week.