UCLA

Alzheimer’s disease (AD) is a fatal neurodegenerative disease and the most common form of dementia in the world today. In women, reproductive life events help shape their biological systems and, therefore, have been identified as a modifying factor of AD risk. Despite this, the relationship between pregnancy life events and AD risk remains poorly understood. I proposed two original competing hypotheses that may explain this relationship. The first hypothesis, known as the estrogen hypothesis, states that pregnancy life events associated with an increase in estrogen exposure will reduce the risk of AD, as estrogen has neuroprotective properties against AD pathogenesis. The second hypothesis, known as the traditional reproductive pattern hypothesis, believes that because earlier populations were less susceptible to AD, reproductive patterns that are consistent with the reproduction patterns of earlier populations will reduce the risk of AD. With these two hypotheses in mind, I conducted a review of the known literature on how parity, age of first birth, and breastfeeding duration are related to AD risk and cognition. I found that there is weak association between pregnancy life events that increase baseline lifetime estrogen exposure and AD risk and that most reproductive patterns of earlier populations are not a reliable predictor of AD risk. However, it still needs to be determined whether baseline lifetime estrogen is relevant in modifying AD risk. Overall, the relationship between pregnancy life events and AD is complex, as they modify multiple risk factors associated with the disease.