Establishing the relationship between cortical atrophy and semantic deficits in Alzheimer’s disease and mild cognitive impairment patients through voxel-based morphometry

The aim of this study was to determine the brain areas responsible for the semantic impairment observed in Alzheimer’s disease (AD) and Mild Cognitive Impairment (MCI) patients. Thirteen AD, 14 MCI patients, and 13 matched healthy older adults were assessed with a test battery aimed to study their semantic competence. Different subtasks were designed to study their semantic knowledge related to objects and faces in the context of semantic retrieval- and semantic association-dependent tasks. Aggregate scores obtained in the different tests were entered into voxel-based regression analyses with grey matter volume values obtained from three-dimensional brain MRI scans. Areas of significant correlation between volume loss and poor semantic scores were restricted to the temporal lobe in the AD group, while in the MCI and control groups significant associations were found with lower grey matter volume values in a widely distributed network of bilateral fronto-temporo-parietal regions. Our results suggest that degradation of partially overlapping and widely distributed neural networks, mainly including temporal regions, subserve semantic deficits related to objects and faces in AD and MCI patients.

► We studied the semantic capacity of AD, MCI and healthy control participants.
► Objects- and faces-related knowledge was assessed with retrieval and association tasks.
► Scores obtained were correlated with grey matter volumes.
► Significant areas were restricted to the temporal lobe in the AD group.
► In the MCI and control groups significant areas were found in a fronto-temporo-parietal network.