A new study has found a link between brain health and oral contraceptives as well as menopausal hormone therapy (MHT). Following its release, Alzheimer's Research UK - the UK's leading dementia research charity - has said that the findings are "interesting" but more information is needed.
Study findings on estrogen exposure
The study, published in Neurology, states that "women are disproportionately affected by Alzheimer disease (AD), a vulnerability that may relate to estrogen fluctuations across the lifespan. Estrogen has neuroprotective and vasoprotective effects, suggesting that lifetime estrogen exposure may influence both AD-related neurodegeneration and cerebrovascular health."
The research, involving 352 women who had a mean age of 70, found that a longer reproductive lifespan was associated with fewer signs of damage to the brain's small blood vessels. Women who had used oral contraceptives or MHT also showed some signs of better brain health.
Signs of better brain health
This included stronger, healthier links between different brain regions and, among MHT users, fewer signs of damage to the brain's small blood vessels. Because this is an observational study, it can't prove cause and effect.
The study's discussion reads: "Greater lifetime estrogen exposure, both endogenous and exogenous, was associated with lower cerebrovascular pathology in women and, among APOE-ε4 carriers, greater cortical thickness in AD-vulnerable regions. These findings support the potential role of cerebrovascular mechanisms linking estrogen exposure to brain ageing. Limitations included observational design and self-reported, binary estrogen exposure. Potential cognitive effects require further studies."
This means that more research is needed to clarify what these findings might mean for women's brain health as they get older.
Alzheimer's Research UK response
Dr Honorine Lebraud, Senior Partnerships Manager at Alzheimer's Research UK, said: "This study builds on growing evidence that reproductive and hormonal history may play a role in brain health as women age.
"Researchers found that women who had a longer reproductive lifespan and therefore experienced a longer period of natural oestrogen exposure, from their first period to menopause, tended to show fewer signs of damage to the brain's small blood vessels. Meanwhile, women who had used oestrogen-based oral contraceptives or menopausal hormone therapy were more likely to exhibit additional signs of improved brain health.
"While these findings are interesting, further research is needed to understand these patterns, especially as nearly two-thirds of people with dementia are women. As an observational study, it cannot show that hormone exposure directly improves brain health or reduces dementia risk.
"For now, our advice remains unchanged. Women should not start or stop taking the contraceptive pill or HRT to reduce their dementia risk based on these findings. Decisions about hormonal treatments should continue to be made with a healthcare professional, based on individual health needs."
The study - Reproductive Lifespan and Hormonal Therapy in Relation to Later-Life Neurovascular Health in Community-Dwelling Older Women - is available online.
