Longitudinal grey matter changes in the healthy aging brain as measured by voxel‐based morphometry

Abstract Background In order to understand the changes that occur in the brain over the course of neurodegenerative disorders, it is imperative to establish how the brain changes over time under healthy conditions (Mattson & Arumugam, 2018). Older adulthood is associated with normal age‐related declines in cognitive functioning (Klimova et al., 2017). However, there are inconsistencies in the literature regarding associated changes in grey matter, with some reporting atrophy across the whole brain and others reporting focal atrophy, localized in the frontal and temporal regions (Pergher et al., 2019; Squarzoni et al., 2018). The current study took a longitudinal approach to investigate changes in grey matter over four years in healthy aging. Methods 3T T1 anatomical magnetic resonance images (MRI) were obtained from 16 healthy older adults (7 male, 9 female; mean age 74.38 ± 4.52 years at baseline) from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database at two time points, four years apart. Voxel‐based morphometry (VBM) analyses were carried out using FMRIB’s Software Library to examine within‐subject changes in grey matter over time. Results Figure 1 depicts regions where there was significant atrophy (p<0.05, corrected for multiple comparisons) in grey matter at four‐year follow‐up compared to baseline. Specifically, VBM results indicated atrophy in distributed areas including bilateral frontal and temporal regions as well as in the hippocampi, bilaterally. However, there were no significant changes in cognitive performance over these four years. Conclusions The current findings reveal atrophy in multiple regions, including the temporal lobes despite normal cognitive performance over the course of four years in healthy aging. Similar regions are known to be affected in Alzheimer’s disease and associated with cognitive decline (Minkova et al., 2017). Follow up work will aim to replicate the current findings in a larger sample and to examine the relationship between cognitive performance and grey matter volume. Developing an understanding of changes in brain structure and function that occur over time in healthy aging will allow for improved interpretation of changes in neurodegenerative conditions, such as Alzheimer’s disease.