Social, economic differences may contribute to sex disparities in dementia risk

Differences in dementia risk between men and women may be attributable to their country’s economy and individual characteristics, according to findings of an international meta-analysis published in Alzheimer’s & Dementia.

Jessica Gong, MSc, a PhD student at the George Institute for Global Health at the University of New South Wales in Australia, and colleagues reported specifically that duration of education and alcohol use had stronger associations with dementia among men compared with women.

Gong and colleagues evaluated all-cause dementia risk among 29,850 participants from 21 studies in 18 countries across six continents that comprised the Cohort Studies of Memory in an International Consortium (COSMIC). Participants had no diagnosis of dementia at baseline assessment from 1993 to 2016.

In total, 2,089 participants developed dementia (66% women). Most (n = 1,442) participants with dementia were from Western countries, comprising 8.6% of participants from those countries. There were 306 cases among 8,031 participants in Asia (3.8%) and 341 cases among 5,075 participants from other countries (6.7%).

Women were more likely to have less education and to have had depression compared with men, and men were more likely to have a smoking history, use alcohol and have high physical activity levels.

Compared with men, women had higher age-adjusted incidence rates (12.3 vs. 16.4 per 1,000 person-years).

Adjusting for age, women had a 12% greater pooled risk for dementia compared with men (HR = 1.12; 95% CI, 1.02-1.23). Subgroup analyses revealed that women in low- to lower-middle-income countries had the greatest risk for dementia compared with men (HR = 1.73; 95% CI, 1.25-2.39).

“When we looked for sex differences in risk factors, we found that, older age, diabetes, depression, hearing impairment and having a certain genetic variation involved in fat metabolism in the brain — known as APOE4 — were associated with a greater risk of dementia in both women and men, while more years of education, higher hip circumference, current alcohol use (vs. never drinking) and high physical activity (vs. none to minimal activity) were associated with a lower risk of dementia in both sexes,” Gong said in a press release.

Sex differences were only observed for two risk factors. Men had a stronger association between former alcohol use and dementia risk (women-to-men ratio of HR = 0.55; 95% CI, 0.38-0.79). Also, there was a moderate difference in the relationship between years of education and dementia risk, with more years of education being a stronger protective factor for men (women-to-men ratio of HR = 1.01; 95% CI 1-1.03).

“These findings justify support for programs to improve gender equity in brain health throughout the life course, particularly in populations that have been previously underrepresented in dementia research,” Gong said in the release.

References:

• Gong J, et al. Alzheimers Dement. 2023;doi:10.1002/alz.12962.
• Multi-country dementia study shows women’s greater risk may be linked to disadvantage. https://www.eurekalert.org/news-releases/979542. Published Feb. 15, 2023. Accessed Feb. 16, 2023.