A new study has linked HRT with dementia. But what does it really tell us?

In the latest study, published in The BMJ, researchers analysed the association with HRT among 5,589 Danish women who had been diagnosed with dementia and 55,890 women who had not. All the women were aged between 50 and 60 at the start of the trial and were followed up over 18 years.

Researchers found a 24 per cent increased risk of dementia in women who had taken oestrogen-progestin HRT – including in those who started treatment aged 55 or younger. Women who had HRT for one year or more had a 20 per cent increased risk, while those who had HRT for eight to 10 years had a 40 per cent increased risk.

“While the study findings are of significant concern, there are some caveats that need to be considered,” says Scientia Professor Kaarin Anstey, the director of the Ageing Futures Institute at the University of New South Wales.

For instance, while about 75 per cent of menopausal women experience symptoms like hot flushes and night sweats, only 28 per cent of women under 55 experiences them in a moderate to severe way.

Women who take HRT usually do so because these symptoms are particularly bothersome, and they are having sleep disturbance and/or mood symptoms, explains Professor Susan Davis, the director of the Women’s Health Research Program at Monash University.

“Hot flushes are associated with reduced blood vessel function and brain-specific blood flow, and poor sleep and low mood are both established risk factors for dementia,” she says, explaining that the low mood could be the dementia risk factor or, alternatively, a change in cognition could be causing low mood.

Loading

“In this study, only 20 per cent [of cases] were Alzheimer’s, and they expected 70 per cent to be Alzheimer’s. So, there was a lot of vascular dementia in there. The elephant in the room is rather than saying, ‘Oh HRT does all these terrible things’, maybe the red flag is why women are taking HRT in the first place.”

It’s a sentiment that is echoed by the authors of an editorial piece responding to the study, who point out that women with less severe symptoms are not as likely to seek out HRT, so while we blame HRT, the severity of the symptoms might be the real issue reflecting the risk factor for dementia.

Davis adds that researchers have not yet properly explored this potential link.

“If you want to see that HRT is bad, you can see it in that paper. But if you really stand back and say, ‘What else could be going on here that we’re not seeing?’ Let’s open our eyes broadly,” she says.

Issues with the study’s methodology need to be teased out, says Anstey. “Further work is needed to clarify this important issue.”

For women confused about whether it is OK to take HRT, Davis – who has just conducted a review of HRT guidelines, which is yet to be released – suggests looking to credible websites like the Australasian Menopause Society.

Blanket statements, she adds, are not always possible as the duration and type of treatment comes down to individuals, their specific health profile and symptoms.

“It’s messy,” she admits of the advice and research around HRT. But, it is clear, she adds, “If women have terrible symptoms, short-term use is beneficial”.

Make the most of your health, relationships, fitness and nutrition with our Live Well newsletter. Get it in your inbox every Monday.