Women less likely to get dementia if they take HRT after menopause, Irish study says

The University of Galway study looked at the impact for women of having high levels of oestrogen during their lives through sources including starting periods at a younger age as girls, having a later menopause, having children and using HRT after menopause. File photo

Women who take HRT after menopause are less likely to get dementia, new Irish research has suggested.

The University of Galway study, which involved over 1,300 women, is one of the first studies to make strong claims about this link. However, women who have early menopause face an increased risk of dementia, it found. 

It looked at the impact for women of having high levels of oestrogen during their lives through sources including starting periods at a younger age as girls, having a later menopause, having children and using HRT after menopause.

Overall, it said: “Our results suggest potential positive cognitive benefits of greater lifetime oestrogen exposure and highlight a possible potential role of oestrogen exposure in modifying brain aging.” 

The aim of the study, led by University of Galway associate professor in medicine Dr Emer McGrath, was to analyse links between reproductive and hormonal factors across a woman’s life and her risk of brain ageing.

The team said while understanding of sex and gender differences in cardiovascular health is growing, understanding around dementia and similar illnesses “significantly lags behind” that.

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The main findings were that entering menopause at an earlier age, less than 49, is associated with an increased risk of dementia. This was compared with women who enter menopause around the ages of 50 and 51.

It also found that taking HRT after menopause appears to be associated with lowering the risk of dementia.

This was linked to a finding that “greater exposure to oestrogen over the reproductive lifespan was associated with enhanced cognitive performance and larger brain volumes”, the study said.

It found that having one to two or more than three children is linked to better cognitive test performances compared to having no children.

The Galway study suggested that higher levels of hormones produced during pregnancy may have a protective effect or that parenting and the larger social circles linked to this may contribute.

However, the paper also noted “conflicting findings” on this, discovered by other studies, which showed an increased dementia risk linked to having a higher number of children. Further study is needed, it concluded.

Oestrogen levels

It also found that higher blood oestrogen levels and being older at the time of menopause were also associated with better cognitive test performance.

This was specifically linked to better visuospatial skills, the study found. This refers to the ability to see, analyse, and mentally manipulate visual and spatial information.

The study highlighted existing knowledge in this area, including that women are more likely than men to suffer from dementia.

“In general, greater exposure to oestrogen throughout a woman’s reproductive lifespan was associated with enhanced cognitive performance and larger brain volumes,” the study concluded.

“Our results may suggest positive cognitive benefits of greater lifetime oestrogen exposure, but require further validation.” 

Dr McGrath's team carried out the study with 1,329 women who did not have dementia, looking at associations between reproductive factors and markers of brain ageing.

This group of women were from the Framingham Heart Study, Boston University which is the world’s longest-running longitudinal cohort study.