Table 2.
Phenotypic correlations between standardized scores (corrected for Age and Age2) for all cognitive and brain volume measures in all participants (n=142).†
| Tot Brain Vol | Neocortex | White Mat. | PFC | VIQ | PIQ | Reading | Proc. Speed | |
|---|---|---|---|---|---|---|---|---|
| Total Brain Volume | -- | |||||||
| Neocortex | .85** | -- | ||||||
| White Matter | .69** | .25* | -- | |||||
| Prefrontal Cortex | .65** | .79* | .21 | -- | ||||
| VIQ | .14 | .01 | .27** | .06 | -- | |||
| PIQ | .42** | .39* | .24* | .35** | .30** | -- | ||
| Reading Score | .22* | .15* | .18* | .09 | .42** | .31** | -- | |
| Processing Speed | .26* | .13 | .28** | .19 | .18* | .52** | .42** | -- |
†
Correlation coefficients presented are computed with all participants, however when both twins are included this violates the independence of the data points. Therefore, the twin pairs were also split randomly and the correlations were re-done in both halves of the split sample, and the significance of those split halves is presented here.
**
Indicates correlation is significant at the p < .05 level in both halves of split sample;
*
indicates significance at the p < .05 level in one of the two halves of the split sample.