Reproductive Markers in Alzheimer's Disease Progression: The Framingham Heart Study

Reproductive status, such as the age of menarche or menopause, may be linked to cognitive abilities and risk for incident Alzheimer's disease (AD) but the evidence is conflicting. It is also not fully known if these factors interact with cortical beta-amyloid deposition.

To study the relationship between reproductive risks, sex hormone markers and risk for decline in specific cognitive domains in women.

We analyzed the association of reproductive markers (age at menarche, number of births, age at menopause, sex hormone-binding globulin, estradiol, estrone, total testosterone, free testosterone) with incident AD and annualized cognitive decline in the community-based longitudinal Framingham Heart Study (FHS) Offspring women 60 years and older (n=772, mean age 68 years, mean follow-up 10.7 ± 3 years). We used the Cox proportional hazards regression model and linear regression model, adjusting for covariates.

Incident AD dementia as well as the annualized change in memory, language, attention and executive functions.

Older age at menopause was associated with a lower risk of incident AD dementia (p = 0.047, 6% lower risk per older year) after adjusting for baseline age, education, hormone therapy status, and MMSE score. Older age at menopause was significantly associated with a slower annualized decline in memory (beta = 0.085, p = 0.00059). The lower level of plasma Aβ42 was also associated with a higher risk of incident AD (HR = 0.97, 95% CI = 0.95, 0.99; p = 0.0039) but there was no significant interaction effect with age at menarche, age at menopause or plasma sex hormone levels.

Younger age at menopause is a risk factor for late-life memory decline and incident AD. This risk appears to be independent of Aβ42 pathology. Further studies to understand the biological and social mechanisms underlying the differential effects of reproductive risks are warranted.