A small observational study by UCLA Health has found that a hormone treatment combining estriol and progesterone may reduce cognitive symptoms associated with menopause, commonly described as brain fog, in a group of menopausal women followed over 12 months. The findings are published in Scientific Reports.
The study enrolled 20 menopausal women with a mean age of 53 who reported cognitive symptoms at baseline. Participants received a customised regimen of estriol and progesterone for 12 months. At the end of the treatment period, participants reported significant improvements in brain fog, concentration, working memory, processing speed, verbal memory, and problem-solving relative to their pre-treatment assessments.
Estriol is a naturally occurring form of oestrogen produced in significant quantities during pregnancy. It has been used in Europe and Asia to treat menopausal symptoms including hot flushes and genitourinary complaints, but differs from estradiol, the most commonly prescribed oestrogen therapy in the United States, in that it binds primarily to a different oestrogen receptor subtype in the brain. Prior research has suggested estriol may have neuroprotective properties, including a potential role in reducing hippocampal atrophy, a region central to learning and memory.
To investigate a possible mechanism, the research team also treated midlife female mice with estriol and found reduced markers of brain pathology in the hippocampus alongside improvements in working and spatial memory performance.
The authors note that the study was a small, uncontrolled case series without randomisation or a placebo group, limiting the generalisability of the findings. They call for larger, placebo-controlled trials incorporating brain imaging and standardised cognitive assessments to confirm whether estriol-based hormone therapy can reliably address menopausal cognitive symptoms, for which no FDA-approved treatment currently exists.
Source: Itoh N et al. Targeting hormone treatment for the brain in menopause. Scientific Reports (2026). DOI: 10.1038/s41598-026-65603-4
