New research has found “no evidence” that commonly prescribed hormone therapies for menopausal women either increase or decrease the risk of dementia.
While experts stress that more studies are needed, the findings are said to “reinforce current clinical guidance” that hormone therapy should be prescribed based on other perceived benefits and risks, rather than for dementia prevention.
Hormone therapy, also known as hormone replacement therapy (HRT), is designed to replace the hormones that naturally decline during menopause.
This treatment helps alleviate a range of symptoms, including hot flushes, mood swings, sleep disturbances, and night sweats.
Available in various forms such as tablets, gels, sprays, or creams, HRT can contain different hormones, including oestrogen, progesterone, and sometimes testosterone.
A comprehensive review conducted by a team of researchers from the UK, Ireland, Switzerland, Australia, and China examined 10 studies involving over one million women.
The team investigated whether HRT use affected the risk of mild cognitive impairment (MCI), which impacts thinking and memory, or dementia in both pre and post-menopausal women.
The study included patients with MCI, those experiencing early menopause, and women with premature ovarian insufficiency, where the ovaries cease functioning before the age of 40.
The analysis, published in The Lancet Healthy Longevity, concluded there was “no significant association” between HRT and the risk of mild cognitive impairment or dementia.
Furthermore, the timing, duration, or specific type of HRT used showed “no significant effects”.
Researchers reiterated that there was “no evidence that” using hormone therapy “either increases or decreases the risk of dementia in post-menopausal women” and that prescriptions should be “based on other perceived benefits and risks and not for dementia prevention”.
They also called for high-quality studies to further clarify the role of hormone therapy and dementia risk, particularly focusing on women with early menopause or mild cognitive impairment.
Dementia disproportionately affects women globally, even when accounting for longer lifespans, with an estimated 982,000 people in the UK living with the condition, approximately two-thirds of whom are women.
Melissa Melville, lead author of the study and a PhD student at UCL psychology and language sciences, highlighted this disparity.
She stated: “Across the globe, dementia disproportionately affects women, even after accounting for women’s longer lifespans, so there’s a pressing need to understand what might be driving that risk, and to identify ways to reduce women’s risk of dementia.”
Ms Melville added: “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.
“Conflicting research and concerns about potential harms have fuelled public and clinical debate, leaving women and clinicians unsure whether menopause hormone therapy might raise or reduce their risk of dementia.”
Professor Aimee Spector, also from UCL psychology and language sciences, noted that the World Health Organisation (WHO) currently provides no guidance on menopause hormone therapy and cognitive outcomes, leaving a critical gap for clinicians and policymakers.
She expressed hope that the review would help inform upcoming WHO guidelines on reducing the risk of cognitive decline and dementia, expected in 2026.
Professor Spector concluded: “To cut through the noise, we reviewed the most rigorous research there is on the subject and found that menopause hormone therapy does not appear to impact dementia risk either positively or negatively.
“More high-quality, long-term research is still needed to fully understand the long-term impacts of menopausal hormone therapy.”
However, menopause specialist Louise Newson offered a different perspective, suggesting it is “impossible to state from this research that HRT does not either increase or reduce dementia risk.”
She argued: “We have known for decades that our three hormones progesterone, estradiol and testosterone are made in our brains and have specific roles in our brains including improving the way the nerve cells grow, function and communicate with each other.”
Ms Newson emphasised the importance of “common sense” in the debate, noting that modern HRT prescribes hormones with the same molecular structure as natural ones, unlike older synthetic types.
She concluded that women prescribed HRT containing progesterone, estradiol, and testosterone experience more benefits than risks, including improved symptoms like memory problems, and reduced future risk of osteoporosis and heart disease.