PROJECT SUMMARY/ABSTRACT There are currently no effective therapies to reduce vascular contributions to cognitive impairment and dementia (VCID). The objective of the parent R01 was to build an understanding of the important interaction between menopause and metabolic health on VCID and identify a novel therapeutic approach to treat VCID in post- menopausal females. We demonstrated that menopause causes weight gain, glucose intolerance, and exacerbates cognitive symptoms in VCID. Conversely, using a 17β-estradiol prodrug therapy we were able to restore cognitive function after menopause. Further, we have preliminary data to suggest reduced endothelial cell (EC) function in menopause may be a contributing factor to cognitive impairment and that estrogen receptor signaling has protective effects on brain ECs (in vivo in mice and in vitro in human ECs). Given that over 80% of individuals with Alzheimer’s disease (AD) have underlying VCID pathology that contributes to dementia progression, the objectives of the current proposal are to define the therapeutic potential of increasing estrogen signaling in the brain in several dementia models and to identify common underlying cellular mechanisms. Despite the high clinical prevalence of multiple etiology dementia (MED), very few studies have examined how AD and VCID interact to produce MED. Our preliminary data show early hippocampal gene changes in AD that are associated with reduced blood brain barrier function. We also discovered that the brain EC translatome is altered in both AD and MED models, even prior to the development of cognitive symptoms, suggesting that targeting brain ECs may be an effective preventative strategy for MED. DHED is a brain-specific 17β-estradiol prodrug that is inactive in the periphery but gets converted to 17β-estradiol only in the brain and is able to activate all 3 estrogen receptors. Given that we, and others, have demonstrated numerous protective effects of estradiol on the cerebral vasculature and we have demonstrated that DHED improves memory after menopause in a dose-dependent manner, we hypothesize that DHED can be used as a preventative strategy to mitigate the vascular impact of (peri-)menopause on MED via improving endothelial health. Since pathology is diverse in MED, we utilize two MED models with different pathologies. Aim 1 will test the hypothesis that peri-menopause induces EC translatome changes and exacerbation of MED pathology that is distinct from changes during menopause. Aim 2 will test the hypothesis that DHED therapy during peri-menopause can reduce underlying pathology and delay onset of cognitive symptoms in MED. Aim 3 will test the hypothesis that DHED improves EC function in human iPSC-derived ECs, with greater protection in cells from APOE4/4 donors. We anticipate these studies will provide mechanistic insight that will facilitate future interventions to decrease the burden of dementia by defining the therapeutic potential of DHED in MED and id...