Sex-Specific Effects of Anxiety on Cognition and Activity-Dependent Neural Networks: Insights from (Female) Mice and (Wo)Men.

Introduction: Neuropsychiatric symptoms (NPS), such as depression and anxiety, are observed in 90% of Alzheimer's disease (AD) patients, two-thirds of whom are women. NPS usually manifest long before AD onset creating a therapeutic opportunity. Here, we examined the impact of anxiety on AD progression and the underlying brain-wide neuronal mechanisms.

Methods: To gain mechanistic insight into how anxiety impacts AD progression, we performed a cross-sectional analysis on mood, cognition, and neural activity utilizing the ArcCreER^T2 x enhanced yellow fluorescent protein (eYFP) x APP/PS1 (AD) mice. The ADNI dataset was used to determine the impact of anxiety on AD progression in human subjects.

Results: Female APP/PS1 mice exhibited anxiety-like behavior and cognitive decline at an earlier age than control (Ctrl) mice and male mice. Brain-wide analysis of c-Fos⁺ revealed changes in regional correlations and overall network connectivity in APP/PS1 mice. Sex-specific eYFP⁺/c-Fos⁺ changes were observed; female APP/PS1 mice exhibited less eYFP⁺/c-Fos⁺ cells in dorsal CA3 (dCA3), while male APP/PS1 mice exhibited less eYFP⁺/c-Fos⁺ cells in the dorsal dentate gyrus (dDG). In the ADNI dataset, anxiety predicted transition to dementia. Female subjects positive for anxiety and amyloid transitioned more quickly to dementia than male subjects.

Conclusions: While future studies are needed to understand whether anxiety is a predictor, a neuropsychiatric biomarker, or a comorbid symptom that occurs during disease onset, these results suggest that there are sex differences in AD network dysfunction, and that personalized medicine may benefit male and female AD patients rather than a one size fits all approach.