Table 2. Childhood IQ at 8 years.
| ALSPAC cohort (N=13 566) |
Final sample (N=1881) |
P | |
|---|---|---|---|
| FSIQ, n (%) | |||
| >70 | 126 (2.3) | 10 (0.5) | 0.001* |
| 70–79 | 345 (6.3) | 51 (2.7) | |
| 80–89 | 759 (13.9) | 137 (7.3) | |
| 90–109 | 2461 (45.0) | 760 (40.4) | |
| 110–119 | 996 (18.2) | 437 (23.2) | |
| 120–129 | 434 (7.94) | 246 (13.1) | |
| ≥130 | 348 (6.36) | 240 (12.8) | |
| Missing | N=8095 | N=0 | |
| VIQ, n (%) | |||
| >69 | 88 (1.6) | 10 (0.5) | 0.001* |
| 70–79 | 227 (4.1) | 25 (1.3) | |
| 80–89 | 621 (11.3) | 121 (6.4) | |
| 90–109 | 2515 (45.7) | 707 (37.6) | |
| 110–119 | 879 (15.98) | 378 (20.1) | |
| 120–129 | 735 (13.4) | 369 (19.6) | |
| ≥130 | 435 (7.9) | 271 (14.4) | |
| Missing | N=8064 | N=0 | |
| PIQ, n (%) | |||
| >69 | 247 (4.5) | 28 (1.5) | 0.001* |
| 70–79 | 516 (9.4) | 98 (5.2) | |
| 80–89 | 875 (15.9) | 216 (11.5) | |
| 90–109 | 2452 (44.7) | 831 (44.2) | |
| 110–119 | 831 (15.1) | 365 (19.5) | |
| 120–129 | 334 (6.1) | 186 (9.9) | |
| ≥130 | 237 (4.3) | 157 (8.4) | |
| Missing | N=8072 | N=0 | |
| Mean FIQ (IQR) | 0.001 | ||
| 102 (91–113) | 109 (99–120) | ||
| Missing | N=8095 | N=0 | |
| Mean VIQ (IQR) | 0.001 | ||
| 104 (95–117) | 111 (101–123) | ||
| Missing | N=8064 | N=0 | |
| Mean PIQ (IQR) | 0.001 | ||
| 97 (86–110) | 104 (92–116) | ||
| Missing | N=8072 | N=0 | |
ALSPAC, Avon Longitudinal Study of Parents and Children; FSIQ, full-scale IQ; VIQ, verbal IQ; PIQ, performance IQ; IQR, interquartile range.
*
P-value was tested by test for trend, otherwise by Pearson’s chi-squared test or unpaired t-test.