Number of individuals | 328 | 319 | |
Handedness, n | | | n.s |
Right | 282 | 275 | |
Non-right | 46 | 44 | |
Race, n | | | n.s |
Caucasian | 270 | 269 | |
African-American | 32 | 27 | |
Asian | 8 | 6 | |
Hispanic | 8 | 12 | |
Other | 10 | 5 | |
Singleton, n | 208 | 198 | n.s |
Member of twin pair, n | 120 | 121 | |
Dizygotic | 59 | 62 | |
Monozygotic | 61 | 59 | |
IQ, mean (SD) | 113 (12.7) | 112 (12.3) | n.s |
SES (SD) | 43 (19.5) | 43 (18.9) | n.s |
Total number of scans | 667 | 607 | |
Number of scans, n | | | n.s |
1 | 133 | 138 | |
2 | 103 | 113 | |
≥3 | 92 | 68 | |
Age at each scan in years, mean (SD) | | | |
First scan | 11.6 (4.7) | 11.7 (5.1) | n.s |
Second scan | 13.5 (4.4) | 13.2 (4.2) | n.s |
Third scan | 15.5 (3.9) | 14.5 (4.0) | n.s |
Age distribution of scans, years | | | |
Mean (SD) | 12.8 (4.9) | 13.2 (5.1) | |
Range | 3.3–31 | 3.7–30.3 | |