Higher cortical thickness/volume in Alzheimer's-related regions: protective factor or risk factor?

Some evidence suggests a biphasic pattern of changes in cortical thickness wherein higher, rather than lower, thickness is associated with very early Alzheimer's disease (AD) pathology. We examined whether integrating information from AD brain signatures based on mean diffusivity (MD) can aid in the interpretation of cortical thickness/volume as a risk factor for future AD-related changes. Participants were 572 men in the Vietnam Era Twin Study of Aging who were cognitively unimpaired at baseline (mean age = 56 years; range = 51-60). Individuals with both high thickness/volume signatures and high MD signatures at baseline had lower cortical thickness/volume in AD signature regions and lower episodic memory performance 12 years later compared to those with high thickness/volume and low MD signatures at baseline. Groups did not differ in level of young adult cognitive reserve. Our findings are in line with a biphasic model in which increased cortical thickness may precede future decline and establish the value of examining cortical MD alongside cortical thickness to identify subgroups with differential risk for poorer brain and cognitive outcomes.& COPY; 2023 Elsevier Inc. All rights reserved.

Automated summary

The study explores the association between cortical thickness/volume and Alzheimer's disease (AD) pathology, indicating that higher thickness may be associated with early AD. The integration of AD brain signatures based on mean diffusivity (MD) helps to interpret the risk factor of cortical thickness/volume for future AD-related changes. The findings suggest a biphasic model where increased cortical thickness precedes decline and emphasize the importance of considering both cortical MD and thickness to identify differential risk subgroups for poorer brain and cognitive outcomes.