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Starting oestrogen hormone therapy during or soon after menopause could cut risk of Alzheimer’s – study

When started within 10 years of menopause, oestrogen-only therapy was associated with a 32% reduction in dementia risk, study finds

The age women start taking HRT and the kind they take could reduce their chances of developing dementia later in life, a new study has found.

About twice as many women have Alzheimer’s disease – the most common type of dementia – compared to men [1].

Researchers performed a meta-analysis of six clinical trials and 45 observational studies, encompassing data from more than six million women, in which women were given oestrogen-based therapy.

Timing matters when starting HRT, study suggests

The findings suggest that women who took hormones in midlife to treat their menopause symptoms were less likely to develop dementia than those who hadn’t taken oestrogen. On the other hand, women taking oestrogen at ages 65 and over did not have a lower chance of an eventual dementia diagnosis compared with women who did not take hormone therapy.

Findings from the study suggest that when started in midlife or within 10 years of menopause:

  • Oestrogen therapy was associated with a 32% reduction in dementia risk
  • Combined oestrogen-progestogen therapy was associated with a 23% reduction in dementia risk

When started after the age of 65:

  • Oestrogen-only therapy had neutral effects
  • Combined oestrogen-progestogen therapy was associated with a non-significant risk increase, largely linked to the use of synthetic progestin.

Oestrogen-only HRT

Oestrogen-only HRT is typically prescribed for women who no longer have a womb, such as after a hysterectomy. Women who still have a womb need to take progestogen to protect the lining of their womb. This can be a synthetic progestogen, but in the UK, women are most commonly prescribed micronised progesterone, which is identical in structure to the progesterone hormone produced in your body.

RELATED: Can HRT reduce your risk of dementia?

Some studies suggest that HRT could potentially reduce the risk of dementia, along with other neurodegenerative diseases, while others have shown no protective effects of HRT [2]. Most studies in this area have studied older types of HRT with synthetic progestogens which are very different metabolically to body identical hormones.

However, we know that female hormones oestrogen, progesterone and testosterone have important biological effects on the brain – including being neurotransmitters, improving glucose metabolism in the brain, being anti-inflammatory and repairing cells in the brain and nervous system. Studies have also shown that the longer time a woman has without hormones, the greater the future risk of dementia. So it is very likely that female hormones reduce future risk of developing dementia.

‘These findings highlight the fact that we need more conclusive research on the possible Alzheimer’s-preventing effect of menopause hormone therapy for women in midlife,’ said study senior author Dr Lisa Mosconi, director of the Alzheimer’s Prevention Program and of the Women’s Brain Initiative and an associate professor in the department of neurology at Weill Cornell Medicine.

Dr Mosconi and her team have begun a clinical trial of oestrogen therapy in midlife women, to see if this has an effect on some of the earliest biomarkers of Alzheimer’s, the most common form of dementia.

The research is published in the journal Frontiers in Aging Neuroscience.


  1. Alzheimer’s Society (2023) ‘Why is dementia different for women?’
  2. Kim, Y. J. et al. (2021), ‘Association between menopausal hormone therapy and risk of neurodegenerative diseases: Implications for precision hormone therapy’, Alzheimer’s and Dementia, 7 (1) e12174, doi:10.1002/trc2.12174
Starting oestrogen hormone therapy during or soon after menopause could cut risk of Alzheimer’s – study

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