Cumulative estrogen exposure, number of menstrual cycles, and Alzheimer's risk in a cohort of British women.
The effect of estrogen on Alzheimer's Disease (AD) risk has received substantial research and media attention, especially in terms of hormone replacement therapy. But reproductive history is also an important modifier of estrogenic exposure, and deserves further investigation. Importantly, there is wide variation in reproductive patterns that modifies estrogen exposure during the reproductive span, which previous AD studies have not incorporated into their calculations. We measured degree of Alzheimer's-type dementia in a cohort of elderly British women, and collected detailed reproductive and medical history information, which we used to estimate number of months with estrogen exposure and number of months with menstrual cycles. Using Cox proportional-hazards models, we find that longer duration of estrogen exposure may have a protective effect against AD risk, such that for every additional month with estrogen, women experienced on average a 0.5% decrease in AD risk (N=89, p=0.02). More menstrual cycles may also have a protective effect against AD risk, although this result was of borderline statistical significance (p<0.10). These results build upon previous methodologies by taking into account a variety of parameters including oral contraceptive use, breastfeeding, post-partum anovulation, abortions, and miscarriages. Additionally, Cox models revealed that longer reproductive span, age>21 at first birth, and more months in lifetime spent pregnant had protective effects against AD risk.
Division of Biological Anthropology, University of Cambridge, Pembroke Street, Cambridge CB2 3QY, United Kingdom. Electronic address: mf392@cam.ac.uk.
Molly
M
Fox
Carlo
C
Berzuini
Leslie A
LA
Knapp
D000328:Adult; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000453:epidemiology* / Q000503:physiopathology; D015992:Body Mass Index; D001835:Body Weight; D015519:Bone Density; D001942:Breast Feeding; D003071:Cognition / Q000502:physiology; D015331:Cohort Studies; D003278:Contraceptives, Oral, Hormonal / Q000494:pharmacology; D015914:Estrogen Replacement Therapy; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008593:Menopause / Q000502:physiology; D008598:Menstruation / Q000502:physiology*; D008875:Middle Aged; D010060:Ovulation; D010298:Parity; D017698:Postmenopause / Q000502:physiology; D011247:Pregnancy; D016016:Proportional Hazards Models; D012098:Reproduction; D017584:Reproductive History; D006113:United Kingdom / Q000453:epidemiology
D003278:Contraceptives, Oral, Hormonal
Alzheimer's; Dementia; Endogenous hormones; Estrogen; Menstrual cycles; Reproductive history