A new study suggests that some risk factors for dementia and Alzheimer’s disease may affect women more strongly than men, even when those risk factors are more common among men.
The study, published in the journal Biology of Sex Differences, analyzed data from more than 17,000 adults and found that hearing loss and diabetes, both more common among men in the sample, were linked to a stronger cognitive impact among women.
Women make up nearly two-thirds of Alzheimer’s patients worldwide. For years, researchers attributed much of the gap to women’s longer life expectancy, since dementia risk rises with age. But the new findings point to a more complex picture, involving biological, social and lifestyle factors.
Researchers from the University of California, San Diego examined 13 known modifiable risk factors for dementia, including education level, sleep problems, hearing and vision loss, smoking, alcohol use, obesity, depression, social isolation, low physical activity, high blood pressure, high cholesterol and diabetes.
The analysis was based on the Health and Retirement Study, a nationally representative U.S. study that follows adults over 50 and their spouses over time.
The researchers found differences between men and women in 10 of the 13 risk factors. Depression was nearly twice as common among women as men, 17% compared with 9%. Physical inactivity was also more common among women, 48% compared with 42%, as were sleep problems, 45% compared with 40%.
Men had higher rates of hearing loss, 64% compared with 50%; diabetes, 24% compared with 21%; and heavy alcohol use, 22% compared with 12%. High blood pressure was common among both groups, affecting about 6 in 10 participants.
Dr. Itamar Ganmor, a neurologist and director of the advanced Alzheimer’s treatment service at Sheba Medical Center in central Israel, said the findings show not only that risk factors differ by sex, but that their effects may differ as well.
“Although hearing loss and diabetes were more common among men, the study showed that their impact on dementia risk was higher among women,” Ganmor said. “They also found that obesity in ages 50 to 60 and high blood pressure affected women’s risk more than men’s.”
Dementia is not a single disease but a syndrome involving a decline in memory, thinking, language or orientation severe enough to affect daily function. Alzheimer’s disease is the most common cause, but dementia can also result from vascular disease, other degenerative diseases, depression, hearing loss, vitamin B12 deficiency and other conditions.
Ganmor said about 45% of overall dementia risk and about 40% of Alzheimer’s risk are linked to modifiable factors.
The researchers said the findings underscore the need to treat sex as a central factor in dementia research and prevention. Rather than focusing only on the most common risk factors in the general population, prevention efforts may need to consider which factors have the strongest cognitive impact for women and men.
For women, the study suggests particular attention may be needed for depression, physical activity and cardiovascular health, including treatment of high blood pressure.
Ganmor said people 50 and older who notice memory problems, language changes, disorientation or other cognitive changes should seek specialist evaluation, especially because newer Alzheimer’s treatments are intended for early stages of the disease and may be more effective when started earlier.
The researchers said more studies are needed to understand how hormones, genetics and access to health care may contribute to sex differences in Alzheimer’s risk.