Hormone therapy study eases concerns over dementia risk

Menopausal hormone therapy (MHT) is not linked to a higher risk of developing dementia, according to a large UK study.

The new findings address results of a recent MHT trial that linked oestrogen-progestogen treatments with a greater risk of dementia.

The NIHR-funded research concluded that use of MHT is not associated with dementia risk with any hormone type, dose, or duration.

A slight increasing risk was found with use of oestrogen-progestogen treatments with a specific diagnosis for Alzheimer’s disease. But this was measurable only when used for five years or more.

The researchers, led by the University of Nottingham and including Southampton’s Professor Michael Moore, say the study “should reassure women in need of menopausal hormonal therapy”. The findings have been published in the BMJ.

Reducing menopausal symptoms

MHT, also known as hormone replacement therapy (HRT), is used to relieve menopausal symptoms such as hot flushes, sleep disturbance, mood swings, memory losses and depression. Treatments include tablets containing oestrogen and progestogen, as well as patches, gels and creams.

Some menopausal symptoms are similar to early signs of dementia. Laboratory studies and small trials have suggested a beneficial link between oestrogen and age-related brain decline. However, the largest trial of MHT, the Women’s Health Initiative Memory Study, found an increased risk of developing dementia among users of oestrogen-progestogen treatments.

To address this uncertainty, this new study set out to investigate the risks of developing dementia for women using any of the menopausal hormone therapy treatments commonly prescribed by the NHS.

Large primary care data sample

MHT prescriptions were analysed for 118,501 women aged 55 and older diagnosed with dementia between 1998 and 2020 (cases). A further 497,416 women were matched by age and general practice but with no records for dementia (controls).

Overall, 16,291 (14%) cases and 68,726 (14%) controls had been exposed to MHT in the period up to three years before diagnosis.

The study assessed overall risk for women exposed to different types of long-term hormone therapy. It also explored the differences between component hormones. This offers new, more reliable estimates for doctors and their patients.

Study co-author Professor Moore said: “Users of hormone therapy for menopause should be reassured by these findings that overall therapy was not associated with any increased risk of dementia, clarifying inconsistent results in earlier research.”