Associations between blood sex hormones, cognitive decline and incident dementia in community-dwelling older Australian women: a prospective cohort study.

Objective: Whether blood sex hormone concentrations predict cognitive decline and incident dementia in older women is uncertain. The Sex Hormones in Older Women (SHOW) study is a prospective cohort study of Australian women, aged at least 70 years, without cognitive impairment.

Methods: Sex hormones were measured by liquid chromatography-tandem mass spectrometry, and comprehensive cognitive testing was performed at baseline and 3 years later.

Results: Of the 6358 participants who had sex hormones measured, 4444 women (median age at baseline 74 years [Q1-Q3 71.7-77.5]) provided data for cognitive analyses. The findings were limited to a decline in executive function and verbal fluency was positively associated with the highest quartiles of estrone (odds ratio [OR] = 1.21, 95% confidence interval [CI] 1.01-1.45, p = 0.04) and dehydro-epiandrosterone (DHEA) (OR = 1.21, 95% CI 1.01-1.45, p = 0.04), compared with the lowest quartiles. Estrone and DHEA were not associated with any other cognitive decline. Testosterone was not associated with cognitive decline. In an exploratory analysis, cognitive decline was not different in women who had estradiol below the limit of detection (66% of women) compared with women with measurable estradiol. Over a median 4.1 years of follow-up (22,518 person-years), 121 (2.2%) developed dementia; an incident rate of 5.3 per 1000 person-years. There were no associations between any hormone and incident dementia.

Conclusions: The finding of a greater likelihood of a decline in executive function and verbal fluency in community-dwelling older women with the highest blood concentrations of DHEA and its metabolite estrone need reaffirmation and their clinical significance should be further investigated. These findings do not support use of estrogen or DHEA therapy to prevent cognitive decline in older women.