Subject characteristics
| Characteristics | Instrumentals (n = 15) | Controls (n = 16) |
|---|---|---|
| Age at start of study (SD) | 6.32 (0.82) years | 5.90 (0.54) years |
| Time from MRI scan 1 to scan 2 (SD) | 15.60 (3.30) months | 14.80 (3.80) months |
| Socioeconomic standard* | 5.10 (0.60) | 4.60 (0.80) |
| Gender | 9 females; 6 males | 7 females; 9 males |
↵*Socioeconomic standard was defined on a six-point scale, with a score of 1, reflecting that the children's parents had some high school education, to a score of 6, reflecting that parents had a doctoral degree (Norton et al., 2005).