Table 2.
Relationships between whole hippocampal volume and hippocampal subfields from bivariate ACE model. Maximum likelihood estimates and 95% CIs for phenotypic (r p), additive genetic (r g), and unique environmental (r e) correlations between total hippocampal volume and specific hippocampal subfields. Residual genetic variance (A residual) after accounting for whole hippocampal volume is presented and corresponds to path a22 in Figure 1c. Estimates are presented separately for the VETSA, and HCP. Common environment correlations were nonsignificant and are not shown
| Subfield | r p | 95% CI | r g | 95% CI | r e | 95% CI | A residual | 95% CI |
|---|---|---|---|---|---|---|---|---|
| VETSA | ||||||||
| Hippocampal tail | 0.67 | (0.60, 0.72) | 0.68 | (0.47, 0.83) | 0.63 | (0.49, 0.74) | 0.39 | (0.21, 0.50) |
| Subiculum | 0.78 | (0.73, 0.81) | 0.81 | (0.67, 0.89) | 0.64 | (0.50, 0.74) | 0.26 | (0.15, 0.33) |
| CA1 | 0.90 | (0.88, 0.92) | 0.95 | (0.90, 1.00) | 0.78 | (0.69, 0.85) | 0.08 | (0.00, 0.13) |
| Hippocampal fissure | 0.47 | (0.38, 0.54) | 0.51 | (−1.00, 1.00) | 0.32 | (0.13, 0.48) | 0.28 | (0.00, 0.47) |
| Presubiculum | 0.57 | (0.49, 0.64) | 0.62 | (0.42, 0.80) | 0.43 | (0.25, 0.58) | 0.49 | (0.26, 0.62) |
| Parasubiculum | 0.30 | (0.20, 0.40) | 0.33 | (0.10, 0.56) | 0.22 | (0.01, 0.41) | 0.64 | (0.44, 0.82) |
| ML | 0.93 | (0.92, 0.95) | 0.98 | (0.95, 1.00) | 0.81 | (0.73, 0.87) | 0.03 | (0.00, 0.08) |
| GC‐DG | 0.87 | (0.84, 0.89) | 0.99 | (0.91, 1.00) | 0.75 | (0.65, 0.83) | 0.01 | (0.00, 0.13) |
| CA3 | 0.70 | (0.64, 0.75) | 0.76 | (0.63, 0.92) | 0.55 | (0.39, 0.68) | 0.34 | (0.12, 0.45) |
| CA4 | 0.86 | (0.83, 0.89) | 0.98 | (0.89, 1.00) | 0.74 | (0.64, 0.82) | 0.03 | (0.00, 0.16) |
| Fimbria | 0.31 | (0.22, 0.41) | 0.46 | (0.21, 0.76) | 0.05 | (−0.16, 0.25) | 0.45 | (0.20, 0.64) |
| HATA | 0.56 | (0.48, 0.63) | 0.71 | (0.36, 1.00) | 0.50 | (0.34, 0.64) | 0.26 | (0.00, 0.47) |
| HCP | ||||||||
| Hippocampal tail | 0.61 | (0.54, 0.66) | 0.63 | (0.49, 0.71) | 0.42 | (0.28, 0.55) | 0.51 | (0.37, 0.61) |
| Subiculum | 0.87 | (0.85, 0.90) | 0.92 | (0.88, 0.96) | 0.56 | (0.43, 0.66) | 0.13 | (0.06, 0.17) |
| CA1 | 0.92 | (0.90, 0.93) | 0.94 | (0.91, 0.96) | 0.80 | (0.73, 0.85) | 0.10 | (0.07, 0.13) |
| Hippocampal fissure | 0.47 | (0.40, 0.54) | 0.86 | (0.59, 1.00) | 0.06 | (−0.10, 0.22) | 0.14 | (0.00, 0.41) |
| Presubiculum | 0.77 | (0.73, 0.81) | 0.84 | (0.74, 0.94) | 0.48 | (0.35, 0.60) | 0.21 | (0.06, 0.30) |
| Parasubiculum | 0.55 | (0.48, 0.61) | 0.55 | (0.31, 0.71) | 0.24 | (0.08, 0.39) | 0.32 | (0.11, 0.48) |
| ML HP | 0.97 | (0.97, 0.98) | 0.98 | (0.97, 0.99) | 0.93 | (0.90, 0.95) | 0.04 | (0.02, 0.04) |
| GC‐DG | 0.92 | (0.90, 0.93) | 0.94 | (0.91, 0.96) | 0.77 | (0.70, 0.83) | 0.10 | (0.07, 0.13) |
| CA3 | 0.71 | (0.66, 0.76) | 0.76 | (0.66, 0.85) | 0.56 | (0.43, 0.66) | 0.31 | (0.19, 0.39) |
| CA4 | 0.89 | (0.87, 0.91) | 0.92 | (0.89, 0.96) | 0.71 | (0.62, 0.78) | 0.12 | (0.07, 0.16) |
| Fimbria | 0.50 | (0.43, 0.57) | 0.60 | (0.39, 0.93) | 0.14 | (−0.03, 0.30) | 0.30 | (0.03, 0.51) |
| HATA | 0.71 | (0.66, 0.76) | 0.85 | (0.67, 1.00) | 0.38 | (0.23, 0.51) | 0.10 | (0.00, 0.29) |
95% CI = corrected 95% confidence intervals; CA = cornu ammonis; GC‐DG = granule cells of the dentate gyrus; HATA = hippocampal amygdala transition area; HCP = Human Connectome Project; ML = molecular layer; VETSA = Vietnam Era Twin Study of Aging.