A new study from researchers at Tohoku University Graduate School of Medicine and the Tokyo Metropolitan Institute of Medical Science has found a concerning link between early menopause and cognitive decline in women. According to the research, women who go through menopause before the age of 40 tend to experience worse cognitive outcomes than those who reach menopause after age 50.
These findings, published on April 15, 2025, in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, could help clinicians better assess dementia risk in women—especially those who enter menopause at an unusually early age.
The research team was motivated by the fact that dementia disproportionately affects women worldwide. While it’s known that early menopause is tied to a higher risk of depression—and depression itself is a known risk factor for dementia—there hasn’t been much direct evidence showing how early menopause impacts long-term cognitive health. That’s exactly what this study aimed to explore.
Using data from the English Longitudinal Study of Ageing, the researchers looked at over 9,000 participants—split almost evenly between men and women. Women were grouped based on when they entered menopause: before 40, between 40 and 49, and after 50. Two years later, the participants were assessed on cognitive tasks like orientation, verbal fluency, and memory recall.
Even after accounting for other modifiable risk factors (like depression, lifestyle, and general health), the data revealed that women who experienced menopause before age 40 consistently performed worse on these cognitive tests than those who went through menopause after 50. Surprisingly, women who hit menopause after 50 actually outperformed the men in some areas of cognitive functioning.
Dr. Miharu Nakanishi, the study’s lead author, emphasized the importance of ruling out other contributing factors to isolate the impact of early menopause itself. “Since early menopause increases the risk of depression, which then increases the risk of dementia, we had to control for this factor to determine if early menopause in and of itself was a direct risk factor,” Nakanishi explained.
Interestingly, hormone replacement therapy (HRT)—often used to ease menopausal symptoms—didn’t seem to influence cognitive function in this study.
These findings suggest that women who undergo early menopause may form a unique, high-risk group for cognitive decline. The team hopes their work will pave the way for further research into how female hormones impact brain health over time.
“Understanding this relationship in-depth could potentially help us design treatments that delay the onset of dementia in at-risk patients,” added Nakanishi.
