Starting HRT soon after menopause may lower Alzheimer’s risk, while beginning later in life could increase risk, new research suggests.

Why this matters for women’s brain health

As women age, levels of the sex hormone oestrogen start to drop, leading to menopause. Menopause signals more than the end of monthly periods: it brings disruptive symptoms like hot flushes, bladder weakness, joint pain, and cognitive changes often described as “menopause brain.”

Oestrogen also plays a role in brain health, helping nerve cells communicate and regulating inflammation. The sharp decline during menopause has led scientists to question whether it contributes to Alzheimer’s and other forms of cognitive decline. This could help explain why women are nearly twice as likely as men to develop dementia. In the UK, dementia is now the leading cause of death in women, with women making up almost two-thirds of people living with the disease (Alzheimer’s Society).

HRT use and Alzheimer’s risk

To help manage menopause symptoms, many women turn to hormone replacement therapy (HRT) such as tablets, patches, or gels containing natural or synthetic versions of oestrogen, often combined with progesterone. In England, over one million women are now prescribed HRT, and uptake is growing rapidly (NHS, 2023).

But does HRT influence Alzheimer’s risk?

A new study presented at the American Neurological Association’s 2025 conference investigated how the timing of HRT affects dementia risk. Dr Fnu Vaibhav and colleagues at Pandit Bhagwat Dayal Sharma University in India reviewed more than 50 studies.

Their findings:

  • Starting HRT within five to ten years of menopause lowered Alzheimer’s risk.
  • Starting after age 65 increased the risk.
  • Randomised trials suggested that beginning HRT later in life could raise Alzheimer’s risk by around 38%, particularly for those using progestin (a synthetic version of progesterone).

One possible explanation is that the clotting properties of these hormones may harm brain blood vessels later in life, impairing oxygen and nutrient supply.

Conversely, studies using health records show that initiating HRT soon after menopause may lower Alzheimer’s risk by up to 32%, potentially due to oestrogen’s protective effects on the brain. However, these observational studies cannot rule out other factors, such as the fact that women who seek HRT are often healthier and have better access to healthcare.

What do UK experts say?

The findings broadly align with NICE guidelines, which recommend HRT mainly for symptom relief and prevention of bone loss in women under 60 or within 10 years of menopause onset. NICE also cautions that starting HRT later in life may increase the risk of heart disease, stroke, and dementia.

Dr Beau Ances, a neurologist at Washington University, who was not involved in the study, commented: “The field is still trying to figure it all out.” Similarly, Professor Susan Davis of Monash University noted that while the findings summarise existing data, no new clinical trials have yet confirmed the protective role of HRT in preventing Alzheimer’s.

The policy perspective

These insights tie into the UK government’s Women’s Health Strategy for England (2022), which prioritises improving access to menopause care and HRT as part of a wider effort to tackle health inequalities. With dementia already placing huge pressure on NHS services, and 1.7 million people in England currently waiting for mental health support, investment in women’s midlife health is seen as crucial for long-term public health outcomes.

The takeaway

While the latest evidence suggests timing matters – with earlier use of HRT potentially lowering Alzheimer’s risk – experts caution against using HRT specifically to prevent dementia. Instead, HRT should be prescribed for menopause symptoms, tailored to a woman’s age and individual risk profile.

Further large-scale, UK-based trials will be essential to determine if HRT can play a preventative role in Alzheimer’s, but for now, its most certain value remains in supporting women through the symptoms of menopause.

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