Women make up nearly two-thirds of Alzheimer’s disease cases in the United States, and scientists have long tried to understand why.
Many people assumed the main reason was simply that women tend to live longer than men. Since Alzheimer’s disease mostly affects older adults, living longer naturally increases the chance of developing dementia.
However, researchers now believe the explanation is much more complicated. A new study from the University of California San Diego School of Medicine suggests that some common health problems and lifestyle factors may damage women’s brain health more strongly than men’s. The findings were published in the journal Biology of Sex Differences on May 19, 2026.
Alzheimer’s disease is the most common form of dementia, a condition that slowly damages memory, thinking, language, and daily functioning. Worldwide, millions of families are affected by dementia every year. As populations continue to age, the number of people living with Alzheimer’s is expected to rise sharply in the coming decades.
Scientists have already identified several factors that can increase dementia risk. These include high blood pressure, obesity, diabetes, smoking, hearing loss, depression, lack of exercise, and poor sleep. Many of these risks are considered “modifiable,” meaning people may be able to lower their risk by improving their health or lifestyle.
In the new study, researchers analyzed information from more than 17,000 middle-aged and older adults across the United States. The data came from the Health and Retirement Study, a large long-running national research project that tracks aging and health.
The research team examined 13 known dementia risk factors and compared how they affected women and men differently. The scientists wanted to look beyond simply how common these risk factors were. Instead, they focused on whether the same health problem might have a stronger effect on women’s cognitive abilities.
The findings revealed several important differences.
Women in the study were more likely than men to report depression, physical inactivity, and sleep problems. About 17% of women reported depression compared with 9% of men. Women were also slightly more likely to exercise less and experience sleep difficulties.
In addition, women had slightly lower average levels of education. Researchers have previously found that education may help protect the brain later in life because mentally stimulating activities may strengthen the brain’s ability to cope with aging-related damage.
Men, on the other hand, had higher rates of hearing loss, diabetes, and heavy alcohol use. Hearing loss was especially common, affecting nearly two-thirds of men in the study.
But one of the most important findings was that some health problems seemed to affect women’s cognition more severely than men’s. Conditions related to heart and metabolic health, such as high blood pressure and obesity, showed stronger links to poorer thinking and memory performance in women.
Even hearing loss and diabetes, which were more common among men, appeared to have a larger negative effect on women’s cognitive health.
The researchers say this means that the same medical condition may not affect everyone equally. A risk factor that causes only moderate problems in men may lead to greater cognitive decline in women.
Dr. Megan Fitzhugh, assistant professor of neurosciences at UC San Diego School of Medicine and first author of the study, explained that prevention strategies may need to become more personalized.
Instead of only focusing on which risk factors are most common, doctors may also need to consider which ones cause the most damage in different groups of people.
The study also highlights the growing importance of precision medicine. Precision medicine aims to tailor prevention and treatment to individual characteristics such as sex, genetics, lifestyle, and health history.
Researchers say the findings may help explain why women face such a large burden from Alzheimer’s disease. Biological factors such as hormones and genetics may interact with cardiovascular health, mental health, and lifestyle in complex ways.
For example, estrogen levels change dramatically after menopause, and some scientists believe these hormonal shifts may affect brain aging and blood vessel health. Women also often experience higher rates of caregiving stress, depression, and sleep disruption throughout life, which may further influence dementia risk.
The researchers emphasize that many of the risk factors identified in the study can potentially be improved. Managing blood pressure, maintaining a healthy weight, treating hearing loss, staying physically active, improving sleep, and addressing depression may all help protect brain health over time.
The findings suggest women may particularly benefit from early prevention efforts focused on heart health and healthy aging.
Still, the researchers caution that the study does not prove these risk factors directly cause dementia in women more than men. More studies will be needed to understand the exact biological and social reasons behind these differences.
At the end of the study, the researchers concluded that a better understanding of sex differences in dementia risk could help doctors develop smarter and more effective prevention strategies.
As scientists continue learning more about how Alzheimer’s disease develops, personalized approaches may become increasingly important in helping people maintain healthy brains as they age.
The study findings are important because they move beyond the simple idea that women develop Alzheimer’s mainly because they live longer. Instead, the research suggests women’s brains may be more sensitive to certain health problems that are already common during aging.
This could help doctors identify high-risk women earlier and encourage more targeted prevention programs. One strength of the study is its very large sample size of more than 17,000 participants, which makes the results more reliable.
However, the study mainly shows associations rather than direct cause-and-effect relationships. Future research will still need to explore the biological reasons behind these differences and whether treating certain risk factors more aggressively in women can lower dementia rates.
If you care about Alzheimer’s, please read studies about Vitamin D deficiency linked to Alzheimer’s, vascular dementia, and Oral cannabis extract may help reduce Alzheimer’s symptoms.
For more information about brain health, please see recent studies about Vitamin B9 deficiency linked to higher dementia risk, and results showing flavonoid-rich foods could improve survival in Parkinson’s disease.
Source: University of California San Diego School of Medicine.
