Exposure to menopausal hormone therapy is not associated with an overall increased risk of dementia in women aged over 55, a large observational study shows.

The findings, published in the BMJ, should provide reassurance to patients and clinicians about the overall safety of hormone treatments, the UK researchers said.

But they added that their data showed that long-term users of oestrogen-progestogen therapies did have a slightly elevated risk of developing Alzheimer’s disease.

The University of Nottingham-led team analysed data from nearly 616,000 women (mean age 83) – 118,500 with a primary diagnosis of dementia between 1998-2000 and almost half a million matched controls – to assess the risks associated with different types and durations of menopausal hormone therapy (MHT).