Menopause and menopausal hormone therapy (MHT) can influence cognition in postmenopausal women, but previous literature remains equivocal about their effects. MHT varies based on formulation and route of administration, both of which influence dose of estradiol (E2), the estrogen with the greatest affinity to the estrogen receptor. Transdermal E2 avoids hepatic conversion and results in higher plasma levels of E2 than oral E2 formulations. The cognitive domains of executive functions, episodic memory and prospective memory are diminished with age, but may be differentially sensitive to MHT, dependent on the brain regions recruited during the task. There is a lack of research investigating the effects of the age of menopause and estradiol (E2)-based MHT on different cognitive domains. Methods: Using baseline data from the Canadian Longitudinal Study of Aging, we examined the associations between age of menopause and E2 based MHT on performance in three cognitive domains: episodic memory, prospective memory, and executive functions . Our cohort included 7,251 postmenopausal women who were cognitively healthy, with models adjusted for age, education, and body mass index. Results: Earlier age at menopause was significantly associated with lower scores across all cognitive domains. However, for the executive functions domain, an earlier age of menopause was associated with lower scores only in those with grand parity (4 or more children) and there was a greater effect size among APOE ε4 carriers. We found that transdermal E2 was associated with higher episodic memory scores, whereas oral E2 was associated with higher prospective memory scores compared to no MHT. Neither administration route significantly affected executive function. Conclusion: These results highlight the differential effects of E2-based MHT depending on route of administration and cognitive domain, and underscore the importance of considering age of menopause and individual characteristics such as reproductive history and genotype status. This work provides clarity to inconsistencies in the literature and informs the development of precision medicine approaches for cognitive aging in postmenopausal people.

The authors have declared no competing interest.

This work was funded by a Canadian Institutes of Health Research (CIHR) Catalyst Grant to LAMG TP and PDG (ACD-170296), and a Four-Year fellowship from the University of British Columbia to TAP.

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