DAVINA McCALL could not believe it when two US neuroscientists told her hormone replacement therapy might reduce the risk of dementia – and she was not the only one.

In the presenter’s Channel 4 documentary Sex, Mind And The Menopause, Dr Lisa Mosconi and Dr Roberta Diaz Brinton from Arizona University said oestrogen could have huge potential in lowering women’s chances of developing Alzheimer’s.

Speaking exclusively to Sun Health, Dr Brinton revealed that women are twice as likely to get dementia because of the way their brain changes during menopause, when oestrogen levels drop and affect brain function.

She said: “On average, women live four and a half years longer than men, but that doesn’t account for a two-fold greater lifetime risk of developing Alzheimer’s disease.

“Our research shows it’s not because women live longer than men. It’s because they begin the disease earlier, in mid-life.”

Due to oestrogen loss during menopause, the brain can suffer a 20 to 25 per cent drop in glucose metabolism, the process that provides the brain with fuel.

That drop can trigger a starvation response in the brain.

It can lead to a decline in white brain matter (which helps different parts of your brain communicate) and an increase in a sticky plaque, called amyloid beta deposition, which, according to Dr Brinton, is “found in greater quantities in people with dementia”.

In theory, prescribing oestrogen to women who are in perimenopause — which starts several years before menopause — could reduce their risk of these problems and dementia.

But HRT is not suitable if, for instance, you have had breast, ovarian or womb cancer.

And oestrogen treatment is no good post-menopause, either. Dr Brinton said: “Using oestrogen as a treatment doesn’t work, as the brain has already changed. It’s needed when women have symptoms.”

She adds there is no data on whether intervening before symptoms would work, and little research has been carried out on HRT and the brain in the UK.

That is not good enough, says Dr Louise Newson, who supports our Fabulous Menopause Matters campaign, especially when 600,000 British women have dementia and it is the leading cause of death in UK women.

The HRT shortages have also forced some women to take drastic action and buy the drugs they need on the black market.

Sam Youngz, 49, a wellness adviser from Telford, Shrops, said: “My nan had dementia and my mum suffers. I’ve been diagnosed with Ehlers-Danlos syndrome, a connective tissue disorder that affects the whole body including the brain. My risk is high.”

Sam went through early menopause at 37 and was shocked by the revelations in Davina’s show. She said: “I was finally diagnosed as menopausal at 44, so the news is too late for me. I don’t know if it would have helped, but I wish I’d had the chance to try.”

Dr Newson said research looking at both women who do and women who do not take HRT could be a game-changer.

She added: “Is it because men have more testosterone in the brain that they are less likely to develop dementia?

“We need answers. We know if women have their ovaries removed, their cognitive function declines faster than women who haven’t had them removed.

“Women who go through early menopause are also more likely to experience dementia. But does giving these hormones back to women help reduce the risk?

“It’s logical to assume putting something back in the brain that helps it function would help. The logic is there. Nothing is proved.”

After four years of low mood, brain fog and insomnia, Katie Taylor, 53, is reaping the benefits of HRT.

The Latte Lounge founder — a website that supports women in mid-life — lives in London with her husband and children, and at 47 was diagnosed as perimenopausal.

She began using oestrogen and progesterone patches and said: “In a few weeks, all my symptoms disappeared. I had energy again.”

She was sleeping better and her “brain clarity” returned.  Katie added: “I can see the difference HRT has made.”

Dr Newson, who had brain fog before starting HRT, said: “Many women think they have dementia. We know brain fog improves with HRT. If it helps reduce dementia risk too, then that’s incredible.”