Perimenopausal state oestradiol to progesterone imbalance drives Alzheimer's risk via ERRα dysregulation and energy dyshomeostasis.

Sex-biased differences in Alzheimer's disease (AD) are well documented, but the mechanisms underlying increased vulnerability in postmenopausal women remain unclear. This study aimed to model the effects of perimenopausal hormonal fluctuations on AD pathophysiology. Using a VCD-induced accelerated ovarian failure model in young female C57BL/6 J and 3xTg mice, we simulated a perimenopausal state with hormonal changes characterised by elevated oestradiol levels and reduced progesterone levels. Supporting human brain transcriptomic and metabolomic data from the ROSMAP study revealed that impaired oestrogen-related receptor alpha (ERRα) function was a key driver of female sex-biased vulnerability. In female mice, progesterone-guided oestrogen receptor signalling maintained ERRα activity by regulating neuronal cholesterol homoeostasis and the TCA cycle. Hormonal imbalances disrupted this mechanism, triggering an aspartate-driven "minicycle," which increased glutamate release, neuronal excitability, ATP depletion, and energy crisis susceptibility. This study demonstrates how perimenopausal hormonal imbalances exacerbate AD risk via ERRα dysfunction, linking neuronal cholesterol and energy homeostasis to disease vulnerability.