Significance of Sex Differences on Gray Matter Atrophy in Alzheimer’s Disease: A Voxel-Based Morphometry Study

Objective: Several voxel-based morphometry (VBM) studies have shown gray matter (GM) reduction as a result of Alzheimer’s disease (AD). However, most of these have not considered GM atrophy in relation to sex differences. Material and Methods: In this paper, we investigate global and local differences of GM using the VBM technique on 3-Tesla 3D T1weighted magnetic resonance imaging (MRI), in four groups of people from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database : males with AD (M-AD, n = 34), age-matched healthy male controls (M-HC, n= 34), females with AD (F-AD, n=34), and age-matched healthy female controls (F-HC, n= 34). The main scope of this research was to identify regions with significant GM loss in male and female cohorts. Analysis of variance (ANOVA) was used to compare means of GM differences between groups. Results: The results indicate that sex plays a significant role in GM atrophy in people with AD. M-AD revealed significant GM reductions in the limbic lobe, the sub-lobar region, and parietal lobe, compared with M-HC, whereas in F-AD, significant GM reductions were located in the limbic lobe, the sub-lobar region, and several areas of the temporal lobe, compared with F-HC. The GM pattern differences between M-HC and F-HC, as well as between M-AD and F-AD, remained. Conclusion: The statistical results obtained by VBM plus DARTEL showed that sex is an important factor in the pattern and severity of GM volume atrophy. The observed different pattern of GM volume reductions may help in understanding the root of AD mechanisms as biomarkers for detection and monitoring, and in explaining different behaviors in people with AD, based on sex.

Author(s): Iman Beheshti, Hasan Demirel and Chunlan Yang

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