Non-stratified analysis of associations with each of the four scholastic tests, for laterality and the hand motor function tests
| Test score | Unadjusted | Adjusted* | |||
| Mean value (SD) | Coefficient (95% CI) | p Value | Coefficient (95% CI) | p Value | |
| Verbal score | |||||
| Laterality† | |||||
| Left | 21.63 (9.46) | −1.19 (−1.77 to −0.62) | <0.001 | −0.91 (−1.46 to −0.36) | 0.001 |
| Mixed | 21.39 (9.19) | −1.43 (−2.12 to −0.74) | <0.001 | −1.03 (−1.69 to −0.38) | 0.002 |
| Left-hand motor score‡ | |||||
| Lowest third | 21.36 (9.29) | −2.19 (−2.62 to −1.75) | <0.001 | −1.21 (−1.73 to −0.68) | <0.001 |
| Middle third | 22.92 (9.11) | −0.62 (−1.04 to −0.19) | 0.004 | −0.12 (−0.56 to 0.33) | 0.610 |
| Right-hand motor score‡ | |||||
| Lowest third | 21.51 (9.35) | −2.10 (−2.52 to −1.68) | <0.001 | −0.84 (−1.35 to −0.32) | 0.001 |
| Middle third | 22.73 (9.08) | −0.88 (−1.31 to −0.46) | <0.001 | −0.30 (−0.75 to 0.15) | 0.192 |
| Non-verbal score | |||||
| Laterality† | |||||
| Left | 20.61 (7.61) | −0.84 (−1.31 to −0.38) | <0.001 | −0.70 (−1.15 to −0.25) | 0.002 |
| Mixed | 20.67 (7.62) | −0.78 (−1.34 to −0.22) | 0.006 | −0.60 (−1.13 to −0.07) | 0.027 |
| Left-hand motor score‡ | |||||
| Lowest third | 20.39 (7.58) | −1.62 (−1.97 to −1.27) | <0.001 | −0.72 (−1.14 to −0.29) | 0.001 |
| Middle third | 21.55 (7.37) | −0.46 (−0.80 to −0.11) | 0.009 | 0.05 (-0.32 to 0.41) | 0.799 |
| Right-hand motor score‡ | |||||
| Lowest third | 20.48 (7.62) | −1.67 (−2.01 to −1.33) | <0.001 | −0.91 (−1.33 to −0.49) | <0.001 |
| Middle third | 21.33 (7.38) | −0.82 (−1.17 to −0.47) | <0.001 | −0.47 (−0.84 to −0.10) | 0.012 |
| Reading ability score | |||||
| Laterality† | |||||
| Left | 15.94 (6.42) | −0.44 (−0.83 to −0.05) | 0.027 | −0.33 (−0.70 to 0.04) | 0.078 |
| Mixed | 15.96 (6.47) | −0.42 (−0.88 to 0.05) | 0.079 | −0.27 (−0.71 to −0.16) | 0.221 |
| Left-hand motor score‡ | |||||
| Lowest third | 15.59 (6.40) | −1.27 (−1.56 to −0.98) | <0.001 | −0.70 (−1.06 to −0.35) | <0.001 |
| Middle third | 16.46 (6.17) | −0.40 (−0.69 to −0.12) | 0.006 | −0.09 (−0.39 to 0.21) | 0.544 |
| Right-hand motor score‡ | |||||
| Lowest third | 15.74 (6.48) | −1.12 (−1.41 to −0.84) | <0.001 | −0.41 (−0.76 to −0.07) | 0.019 |
| Middle third | 16.33 (6.10) | −0.53 (−0.82 to −0.24) | <0.001 | −0.18 (−0.48 to 0.13) | 0.256 |
| Mathematics test score | |||||
| Laterality† | |||||
| Left | 16.56 (10.33) | −0.83 (−1.48 to −0.19) | 0.011 | −0.70 (−1.31 to −0.10) | 0.023 |
| Mixed | 16.33 (10.31) | −1.06 (−1.83 to −0.29) | 0.007 | −0.87 (−1.60 to −0.15) | 0.018 |
| Left-hand motor score‡ | |||||
| Lowest third | 15.91 (10.20) | −2.36 (−2.85 to −1.88) | <0.001 | −1.32 (−1.90 to −0.73) | <0.001 |
| Middle third | 17.55 (10.24) | −0.72 (−1.19 to −0.25) | 0.003 | −0.17 (−0.67 to 0.32) | 0.499 |
| Right-hand motor score‡ | |||||
| Lowest third | 16.13 (10.30) | −2.13 (−2.60 to −1.66) | <0.001 | −0.88 (−1.45 to −0.32) | 0.002 |
| Middle third | 17.37 (10.18) | −0.90 (−1.38 to −0.42) | <0.001 | −0.28 (−0.78 to 0.22) | 0.275 |
↵* Adjusted for laterality, left-hand motor score, right-hand motor score, sex and parental social class.
↵† Right-handed as the reference category.
↵‡ The lowest third of the motor function tests indicates poorest performance (longest time to pick up 20 matches). The highest third is used as the reference category.