Hormone replacement therapy (HRT) is associated with a small but significantly increased risk of Alzheimer’s disease (AD), research published in The BMJ suggests (6 March 2019)
Study authors looked at data on 84,739 post-menopausal women from Finland diagnosed with AD between 1999 and 2013, matched to an equal number of women without a diagnosis.
Overall, the odds of AD diagnosis was 9% higher in users of oestradiol-only therapy and 17% higher in users of oestrogen-progestogen therapy, but the difference in risk between these two groups was not significant. By contrast, exclusive use of vaginal oestrogen was not associated with increased AD risk.
In absolute terms, the researchers estimated that use of systemic hormone therapy was linked to 9–18 additional AD diagnoses in every 10,000 women aged 70–80 years, especially in those who had taken HRT for at least ten years.
The potential role of HRT in dementia has previously been unclear, with some studies finding it protective and others indicating an increased risk, the researchers explained.
“Hormone therapy users should be informed of a possible risk of the disease with prolonged use, even though the absolute risk elevations are small,” they said.
 Savolainen-Peltonen H, Rahkola-Soisalo P, Hoti F et al. Use of postmenopausal hormone therapy and risk of Alzheimer’s disease in Finland: nationwide case-control study. BMJ 2019;364:1665. doi: 10.1136/bmj.l665