Table 2: Adjusted associations between social engagement (independent variable) and ROI volumes (dependent variables).

ROIMean volume (cc)Social engagement standardized coefficient 𝑃 value

Total brain volume1137.960.0370.011
Total gray matter (GM)534.140.0720.007
Total white matter (WM)603.820.0010.975
Gray matter lobes
 Frontal GM134.850.0370.273
Temporal GM96.580.0830.009
 Parietal GM65.400.0680.081
Occipital GM45.560.0760.048
White matter lobes
 Frontal WM201.470.0080.761
 Temporal WM119.030.0210.501
 Parietal WM106.080.0260.456
 Occipital WM58.220.0070.869
Smaller structures
 Cerebellum119.63 −0.013 0.763
 Medial structures80.630.0470.135
 Cingulate gyrus21.020.0450.269
 Insula13.940.0080.865
Corpus callosum11.890.1270.004
 Internal capsule9.850.0260.520
 Hippocampus7.42 −0.004 0.923
 Amygdala2.430.0370.453
 Entorhinal cortex2.37 −0.016 0.756

From models adjusted for age, education, intracranial volume, race/ethnicity, hypertension, diabetes, handedness, and control status.
Bold: 𝑃 0 . 0 5 .