Brain structural variability due to aging and gender in cognitively healthy Elders: results from the Sao Paulo Ageing and Health study

Abstract

Background and purpose: Several morphometric MR imaging studies have investigated age- and sex-related cerebral volume changes in healthy human brains, most often by using samples spanning several decades of life and linear correlation methods. This study aimed to map the normal pattern of regional age-related volumetric reductions specifically in the elderly population.

Materials and methods: One hundred thirty-two eligible individuals (67-75 years of age) were selected from a community-based sample recruited for the São Paulo Ageing and Health (SPAH) study, and a cross-sectional MR imaging investigation was performed concurrently with the second SPAH wave. We used voxel-based morphometry (VBM) to conduct a voxelwise search for significant linear correlations between gray matter (GM) volumes and age. In addition, region-of-interest masks were used to investigate whether the relationship between regional GM (rGM) volumes and age would be best predicted by a nonlinear model.

Results: VBM and region-of-interest analyses revealed selective foci of accelerated rGM loss exclusively in men, involving the temporal neocortex, prefrontal cortex, and medial temporal region. The only structure in which GM volumetric changes were best predicted by a nonlinear model was the left parahippocampal gyrus.

Conclusions: The variable patterns of age-related GM loss across separate neocortical and temporolimbic regions highlight the complexity of degenerative processes that affect the healthy human brain across the life span. The detection of age-related limbic GM decrease in men supports the view that atrophy in such regions should be seen as compatible with normal aging.

Fig 1.

Negative correlations between regional GM and age in male and female subgroups. Voxels that surpassed the initial threshold of P < .01 in the statistical parametric maps are marked with the red scale and overlaid on reference 3D rendering images spatially normalized to the Talairach and Tournoux atlas. Numbers indicate the clusters that retain statistical significance at the P < .05 threshold, corrected for multiple comparisons at the voxel level (FWE): right middle and superior temporal gyri (1), right dorsomedial frontal cortex (2), bilateral orbitofrontal cortex (3), left parahippocampal gyrus (4), and bilateral amygdala (5).

Fig 2.

Plots of GM versus age (including best-fit regression lines). Male or female subgroups at the P < .05 threshold are represented only in regions in which at least 1 regression model is significant for the overall sample.