Longitudinal Surface-Based Morphometry Reveals Potential MRI Biomarkers Correlated with Multidimensional Brain Health...

Characterizing longitudinal brain changes linked to brain health requires identifying structural and neuroanatomical biomarkers. This study aimed to discover MRI-based biomarkers for the Brain Health Index (BHI), a multidimensional measure of cognition, emotional well-being, and social connectedness, and assess their feasibility as indicators of brain health improvement. We investigated neuroanatomical correlates of BHI using longitudinal surface-based morphometry in 210 healthy adults (aged 20-70). We hypothesized that baseline brain morphology would predict BHI performance and that longitudinal BHI changes would correlate with morphometric changes. Participants underwent up to five MRI scans over four years. Surface-based analyses quantified changes in cortical volume, thickness, sulcal depth (SD), gyrification index (GI), and fractal dimension (FD). Vertex-wise regressions tested associations between baseline BHI and morphometric changes, and between longitudinal BHI changes and morphometric features, controlling for age, sex, education, and scan interval. In males, baseline BHI predicted increased FD in the left inferior parietal cortex. In the whole group, BHI gains correlated with increased GI in the left insula and posterior cingulate. In females, BHI improvements were linked to greater SD in the left precuneus, middle temporal, and right cingulate gyri. A sex-specific interaction showed BHI gains in males associated with increased GI in the left insula and temporal cortices. These findings highlight FD, GI, and SD as potential MRI biomarkers for tracking changes in brain health, revealing sex-specific neuroanatomical associations with BHI improvements in regions such as the insula and precuneus.