Women’s Health Series: Menopausal Hormone Therapy Not Linked to Dementia

Study findings published in The BMJ reveal that the use of menopausal hormone therapy (MHT) is not strongly linked to an increased risk of developing dementia in women.

MHT is a therapy used to relieve menopausal symptoms in women. These symptoms include hot flushes, trouble sleeping, mood swings, depression, and even memory loss. Treatments include tablets containing oestrogen only, or a combination of oestrogen and progestogen. Additionally, there are treatments in the form of patches, gels and creams.

Studies and small trials have suggested a beneficial link between oestrogen and age-related brain decline. However, the largest trial of MHT, the Women’s Health Initiative Memory Study, found an increased risk of developing dementia among users of oestrogen-progestogen treatments.¹

A large observational study conducted in Finland showed an increased possibility of developing Alzheimer’s disease in users of both oestrogen-only and oestrogen-progestogen treatments. There were some methodological weaknesses in the study, however. To address this, researchers at the Universities of Nottingham, Oxford and Southampton investigated the risks of developing dementia using any of the menopausal hormone therapy treatments commonly prescribed within the UK National Health Service.¹

Scientists used two United Kingdom primary care databases, QResearch and Clinical Practice Research Datalink, to analyze MHT prescriptions for the 118,501 women aged 55 and older diagnosed with dementia between 1998 and 2020.

All information from MHT prescriptions given more than three years before the case diagnosis was evaluated, including hormone type, dose, and method of administration. Other factors, such as family history, smoking, alcohol consumption, pre-existing conditions, and other medications taken were considered. 16,291 cases and 68,726 controls had been exposed to menopausal hormone therapy in the period up to three years before diagnosis.

However, an analysis of cases with a specific diagnosis of Alzheimer’s disease showed a small increase in risk associated with oestrogen-progestogen therapy. This increased slowly with each year of exposure, reaching an average 11 percent increased risk for use of between 5 and 9 years. There was an average of 19 percent for use of 10 years or more.

This is an observational study, so cause cannot be established, and the researchers acknowledge limitations, such as incomplete recording of menopausal symptoms, particularly for women registered after menopause, that may have affected results.

“The findings will be helpful to policy makers, doctors, and patients when making choices about hormone therapy,” they conclude.¹

Reference

1. Use of Menopausal hormone therapy and risk of dementia: Nested case-control studies using QResearch and CPRD databases. The BMJ. Accessed October 5, 2021 doi: https://doi.org/10.1136/bmj.n2182.