A major international review has concluded there is no significant evidence that hormone replacement therapy (HRT) either increases or decreases the risk of developing dementia. The findings, published in The Lancet Healthy Longevity, aim to cut through years of conflicting advice and public concern surrounding the treatment used by millions of women to manage menopausal symptoms.
What the Comprehensive Review Found
Researchers from the UK, Ireland, Switzerland, Australia, and China analysed data from 10 studies involving over one million women. They investigated whether using HRT affected the risk of mild cognitive impairment (MCI) or dementia in both pre and post-menopausal women, including those with early menopause or premature ovarian insufficiency.
The analysis found no significant association between HRT use and the risk of MCI or dementia. Crucially, the timing of starting therapy, how long it was used for, or the specific type of hormones prescribed also showed no significant effects on cognitive outcomes.
Clarity for Women and Clinicians
Lead author Melissa Melville, a PhD student at UCL's psychology and language sciences department, highlighted the global urgency of the issue. Dementia disproportionately affects women, with around two-thirds of the estimated 982,000 people living with the condition in the UK being female, even after accounting for longer female lifespans.
"Menopause hormone therapy is widely used to manage menopausal symptoms, yet its impact on memory, cognition and dementia risk remains one of the most debated issues in women’s health," Ms Melville stated. She added that the review's findings should help reassure women and clinicians that HRT does not appear to impact dementia risk either way.
Calls for More Research and Informed Guidance
Professor Aimee Spector, also from UCL, noted a critical gap in global health guidance. She pointed out that the World Health Organisation (WHO) currently provides no guidance on menopause hormone therapy and cognitive outcomes. The research team hopes their work will inform upcoming WHO guidelines on reducing dementia risk, expected in 2026.
While the review reinforces current UK clinical guidance—that HRT should be prescribed based on its benefits for symptom relief and other health risks, not for dementia prevention—the authors called for more high-quality, long-term studies. They emphasised a particular need for research focusing on women who experience early menopause or already have mild cognitive impairment.
However, some experts urge continued caution. Menopause specialist Dr Louise Newson suggested it is "impossible to state from this research that HRT does not either increase or reduce dementia risk." She argued that hormones like progesterone, estradiol, and testosterone have vital roles in brain function and that modern, body-identical HRT formulations offer significant benefits for symptoms like memory problems, alongside reducing future risks of osteoporosis and heart disease.
The study, published on Tuesday 23 December 2025, represents a significant step in clarifying a complex and often worrying issue for women navigating menopause treatment options.
