Menopause hormone therapy not linked to dementia, review suggests

A WHO-commissioned systematic review of more than one million women found no strong evidence that menopause hormone therapy changes dementia risk; most studies were observational and rated low certainty.

A large WHO-commissioned systematic review examined whether menopause hormone therapy (MHT), also called hormone replacement therapy, is linked to dementia risk. The analysis pooled data covering more than one million women and was published in the journal Healthy Longevity. The authors found no strong evidence that MHT increases or decreases dementia risk. Most available studies were observational, inconsistent, and assessed as low certainty. Key findings: - The review covered over one million women and was commissioned by the World Health Organization. - Overall, the analysis did not find strong evidence that MHT affects dementia risk either way. - Most studies were observational with inconsistent small associations and low certainty, so they cannot establish cause and effect. - One randomized controlled trial reported a possible increase in dementia risk with estrogen-only MHT in women over age 65, but the authors rated that finding as low certainty and reported an absolute risk difference of about 6.27 additional cases per 1,000 women. - The review’s conclusions align with a 2024 Lancet Commission finding of insufficient evidence, and follow the FDA’s recent announcement about plans to remove the dementia 'black box' warning on MHT products. - The authors called for higher-quality research and more data on people who experience premature menopause, including after hysterectomy or oophorectomy. Summary: The review concludes that current evidence does not support a clear link between MHT and dementia risk and that existing studies vary in design and quality. The findings are expected to inform forthcoming WHO guidance on cognitive decline and dementia due in 2026, and researchers say additional high-quality trials and subgroup data are needed to clarify the relationship.