Click here for updates on this story

Toronto, Ontario (CTV Network) — Research has shown more women worldwide are affected by dementia than men, and a broad new study suggests gender-based social and economic disadvantages may be to blame.

According to a meta-analysis of 21 international studies involving 29,850 people from 18 countries, gender disparity — rather than sex, average lifespan, and other biological factors alone — appears to play a significant role in determining who develops dementia and who doesn't.

The study was published in the Journal of the Alzheimer's Association on Feb. 15. Of the participants studied, 58 per cent were women, none had dementia at the onset of the research, and 2,089 had been diagnosed with dementia as of later follow-up. The period between study onset and follow-up ranged from 0.01 to 19.6 years, depending on the patients and the studies they participated in.

While men studied were more likely to have smoked in their lifetimes, to be consuming alcohol during the study period and to have engaged in high levels of physical activity, women had fewer years of education and were more likely to have had depression in their lifetimes. They also accounted for 66 per cent of dementia cases recorded during the course of the study. The average age of participants at the study onset was 72 years for women and 71 years for men.

The study also found that racialized people and those in low- to lower-middle income countries were more likely to suffer from dementia.

Lead author Jessica Gong, from the George Institute for Global Health, said the findings challenge previous research that suggested women face a greater risk of developing dementia than men because they live longer, on average.

“Most research estimating dementia incidence to date has been conducted in high-income countries, with very little data available in the countries that actually bear the greatest burden,” Gong said in a media release.

“We found that when adjusted for age, rates of dementia were highest among low- to lower-middle income countries, and higher in women than men.”

According to the study, the number of people living with dementia is expected to surpass 150 million worldwide by 2050 — three times the 2019 estimate of 50 million — and rates are increasing most rapidly in low- and middle-income countries.

In developing their study, Gong said she and her co-authors took some cues from the 2020 Lancet Commission Report, which estimated that as much as 40 per cent of dementia risk could be attributed to 12 controllable risk factors, many of which are more common in low- and middle-income countries.

These factors include less education, hypertension, obesity, diabetes, depression, hearing impairment, smoking, excessive alcohol consumption, physical inactivity, low social contact, traumatic brain injury and air pollution.

“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,” Gong said.

“More years of education, higher hip circumference, current alcohol use and high physical activity were associated with a lower risk of dementia in both sexes. But there was moderate evidence for a sex difference with years spent in education, indicating a stronger protective association for men than women.”

Gong and her co-authors found that women, particularly in low- and middle-income countries, do not have the same access as men to factors that help protect against dementia, such as higher levels of education and mentally-stimulating work.

Sanne Peters, a member of the research team and senior lecturer at the George Institute for Global Health U.K., explained that factors restricting women’s opportunities, barriers to appropriate health care and other factors such as domestic violence — particularly among women from lower socioeconomic settings — can lead to psychological stress and financial instability. In turn, these outcomes affect women's late-life cognitive health.

“In general, the geographical patterns that we saw for increased dementia risk in women seemed to echo those of gender disparity,” Peters said in a media release.

“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.”

The-CNN-Wire
™ & © 2023 Cable News Network, Inc., a Warner Bros. Discovery Company. All rights reserved.