HRT could help ward off dementia – but only if women take it when their menopause begins

Hormone replacement therapy can reduce the risk of dementia in women with early menopause – but only if they start treatment promptly, a study suggests.

Women make up around two-thirds of people with Alzheimer’s, with early menopause linked to a heightened risk of the illness.

Now a study claims that those who are prescribed HRT from the onset of symptoms are at no greater risk.

But women who start the treatment – which helps control menopause symptoms – several years later, had higher levels of two key proteins involved in dementia, beta-amyloid and tau.

Experts said it was not yet clear how the menopause and hormone therapy affected the brain, with further research needed.

In the latest study, researchers from Mass General Brigham, Boston, US, used brain imaging to study how the presence of two proteins involved in Alzheimer’s related to age at menopause and HRT use.

They studied scans from 292 cognitively unimpaired adults to determine levels of amyloid and tau in seven regions of the brain.

They found women had greater levels of tau compared to men of the same age, especially in cases where they also had elevated beta-amyloid.

Tau levels were high in the regions of the brain close to the memory-centre of the brain and areas that are known to be involved in the progression of Alzheimer’s dementia.

The association between abnormal levels of the proteins was stronger in women who had earlier menopause onset, defined as under the age of 45, than women overall.

Given that many women who undergo premature menopause often use HRT, researchers wanted to examine whether its use was linked with the two proteins.

Starting the therapy late – five years or more after menopause onset – was associated with higher levels of beta-amyloid and tau, according to the findings in Jama Neurology.

Rachel Buckley, of Massachusetts General Hospital, said: ‘We found that the highest levels of tau, a protein involved in Alzheimer’s disease, were only observed in hormone therapy users who reported a long delay between age at menopause onset and their initiation of hormone therapy.

‘The idea that tau deposition may underlie the association between late hormone therapy intervention and Alzheimer’s disease dementia was a huge finding, something that hadn’t been seen before.’

Evidence on the role of HRT in dementia has so far proven inconclusive, with research suggesting it can have both protective and potentially harmful effects.

In January, a study by University of East Anglia researchers suggested that HRT may help prevent Alzheimer’s in women carrying the APOE4 gene, which puts them at heightened risk.

That suggested HRT was most effective when given during perimenopause, where symptoms build up months or years before periods actually stop.

Alzheimer’s Research UK said larger studies were needed to help understand the link between HRT and changes to the brain.

The charity pointed to conflicting previous research, with some highlighting potential cognitive benefits of HRT while other studies pointed to an increased risk of memory and thinking problems.

Dr Sara Imarisio, head of research, said: ‘While this study contributes valuable new data to this topic, we still aren’t able to point to a definitive link between hormone therapy and Alzheimer’s or dementia.

‘It’s important that people are empowered with evidence-based advice that allows them to make informed decisions about their health. But there’s a lot more to understand about how menopause and HRT influence dementia risk.

‘We need to see larger studies and controlled clinical trials to better understand this complex area of research and make sense of conflicting findings that have emerged in recent years.’