Table IV.
Univariate ACE model maximum likelihood parameter estimates and P values
| Variance components (95% CI) | Hypothesis test (P values) | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| a 2 | c 2 | e 2 | A | C | A and C | ||||
| ICV | 0.73 | (0.68, 0.92) | 0.15 | (0.00, 0.48) | 0.13 | (0.13, 0.23) | 0.0001 | 0.4976 | <0.0001 |
| Lateral ventricles | 0.71 | (0.68, 0.84) | 0.00 | (0.00, 0.00) | 0.29 | (0.16, 0.53) | 0.0045 | 1.0000 | 0.0001 |
| Total GM | 0.56 | (0.56, 0.90) | 0.29 | (0.00, 0.59) | 0.14 | (0.08, 0.26) | 0.0017 | 0.1659 | <0.0001 |
| Total WM | 0.85 | (0.85, 0.94) | 0.05 | (0.01, 0.05) | 0.09 | (0.05, 0.17) | <0.0001 | 0.8065 | <0.0001 |
| Total EM | 0.19 | (0.05, 0.44) | 0.00 | (0.00, 0.00) | 0.81 | (0.56, 1.00) | 0.3833 | 1.0000 | 0.3867 |
| Total CSF | 0.63 | (0.58, 0.77) | 0.00 | (0.00, 0.00) | 0.37 | (0.23, 0.59) | 0.0200 | 1.0000 | <0.0001 |
| Cortical GM | 0.58 | (0.41, 0.90) | 0.27 | (0.00, 0.58) | 0.15 | (0.09, 0.26) | 0.0017 | 0.2131 | <0.0001 |
| Cortical WM | 0.85 | (0.50, 0.94) | 0.05 | (0.00, 0.40) | 0.10 | (0.06, 0.18) | <0.0001 | 0.8065 | <0.0001 |
| SubCortGM | 0.62 | (0.48, 0.76) | 0.00 | (0.00, 0.00) | 0.38 | (0.24, 0.61) | 0.0191 | 1.0000 | <0.0001 |
| Cerebellum | 0.17 | (0.00, 0.53) | 0.62 | (0.28, 0.82) | 0.21 | (0.12, 0.36) | 0.3125 | 0.0015 | <0.0001 |
| Prefrontal GM | 0.30 | (0.00, 0.77) | 0.36 | (0.00, 0.69) | 0.34 | (0.21, 0.57) | 0.2815 | 0.1859 | <0.0001 |
| Frontal GM | 0.31 | (0.25, 0.78) | 0.36 | (0.00, 0.69) | 0.32 | (0.20, 0.54) | 0.2207 | 0.1435 | <0.0001 |
| Parietal GM | 0.65 | (0.65, 0.86) | 0.12 | (0.00, 0.51) | 0.23 | (0.14, 0.41) | 0.0089 | 0.6242 | <0.0001 |
| Occipital GM | 0.57 | (0.51, 0.86) | 0.21 | (0.00, 0.58) | 0.23 | (0.13, 0.40) | 0.0179 | 0.3897 | <0.0001 |
| Prefrontal WM | 0.53 | (0.53, 0.88) | 0.29 | (0.00, 0.63) | 0.18 | (0.11, 0.33) | 0.0117 | 0.2435 | <0.0001 |
| Frontal WM | 0.84 | (0.72, 0.91) | 0.00 | (0.00, 0.00) | 0.16 | (0.09, 0.28) | <0.0001 | 1.0000 | <0.0001 |
| Parietal WM | 0.72 | (0.72, 0.88) | 0.07 | (0.00, 0.45) | 0.21 | (0.12, 0.37) | 0.0033 | 0.7518 | <0.0001 |
| Occipital WM | 0.86 | (0.58, 0.92) | 0.00 | (0.00, 0.00) | 0.14 | (0.08, 0.25) | 0.0001 | 1.0000 | <0.0001 |
| Total prefrontal | 0.42 | (0.42, 0.86) | 0.38 | (0.00, 0.70) | 0.20 | (0.12, 0.36) | 0.0421 | 0.1336 | <0.0001 |
| Total frontal | 0.64 | (0.64, 0.85) | 0.11 | (0.00, 0.51) | 0.25 | (0.15, 0.43) | 0.0121 | 0.6468 | <0.0001 |
| Total parietal | 0.74 | (0.61, 0.89) | 0.09 | (0.00, 0.45) | 0.18 | (0.11, 0.32) | 0.0011 | 0.7083 | <0.0001 |
| Total occipital | 0.74 | (0.36, 0.91) | 0.11 | (0.00, 0.47) | 0.15 | (0.09, 0.27) | 0.0004 | 0.6242 | <0.0001 |
| RHem GM | 0.44 | (0.44, 0.86) | 0.36 | (0.00, 0.67) | 0.20 | (0.12, 0.35) | 0.0272 | 0.1016 | <0.0001 |
| LHem GM | 0.71 | (0.71, 0.92) | 0.15 | (0.00, 0.49) | 0.13 | (0.08, 0.24) | 0.0002 | 0.4839 | <0.0001 |
| RHem WM | 0.82 | (0.75, 0.94) | 0.08 | (0.00, 0.42) | 0.10 | (0.06, 0.17) | <0.0001 | 0.7083 | <0.0001 |
| LHem WM | 0.79 | (0.79, 0.91) | 0.07 | (0.00, 0.43) | 0.15 | (0.09, 0.27) | 0.0003 | 0.7642 | <0.0001 |
| RHem Tot | 0.64 | (0.61, 0.92) | 0.25 | (0.00, 0.55) | 0.12 | (0.07, 0.21) | 0.0002 | 0.2384 | <0.0001 |
| LHem Tot | 0.74 | (0.74, 0.93) | 0.15 | (0.00, 0.48) | 0.11 | (0.06, 0.19) | <0.0001 | 0.4751 | <0.0001 |
| Corpus callosum | 0.04 | (0.04, 0.66) | 0.54 | (0.00, 0.70) | 0.42 | (0.27, 0.60) | 0.8875 | 0.0693 | <0.0001 |
Adjusted for gender, gestational age at birth, and gestational age at MRI.
Abbreviations: CSF, cerebrospinal fluid; EM, early myelinated white matter; GM, gray matter; ICV, intracranial volume; LHem, left hemisphere; RHem, right hemisphere; WM, unmyelinated white matter.