Association between depression, gender and Alzheimer's neuropathology in older adults without dementia

Previous studies regarding the relationship between depression and Alzheimer's neuropathology in older adults without dementia have reported conflicting findings. This study examined whether depression is associated with Alzheimer's neuropathology and whether sex moderates these relationships.

This is a cross-sectional study of older adults without dementia (normal cognition or mild cognitive impairment, age 50+; CDR ≤ 0.5) who had autopsy within 1 year of their last clinic visit in the National Alzheimer's Coordinating Center database (2005-2020). Logistic regression models were fitted to determine if a recent or remote history of depression was associated with amyloid spread beyond the neocortex measured by modified Thal phase score, density of amyloid plaques measured by CERAD score or tau neuropathology measured by modified Braak score. A moderator analysis was performed to determine if any of these associations were moderated by sex.

This study included 407 participants (96 Thal, 405 Braak, and 406 CERAD). Those who had recently active depression (within previous 2 years) but not remote depression only were more likely to have higher Thal phase score compared to those without a history of depression (OR = 3.74; 95% CI, 1.15-12.17; p = 0.028). Sex did not moderate this association. No significant associations between recent depression and Braak or CERAD scores were observed.

Our findings indicate that the association between late life depression and Alzheimer's neuropathology is associated with spread of amyloid pathology beyond the neocortex to include allocortical and subcortical regions critical for regulation of mood and motivated behavior.