Social and economic disadvantages that women face may explain the higher risk of dementia in them, researchers of a large international study involving almost 30,000 people from 18 countries covering all six continents suggested.

Though almost no evidence exists regarding most of the risk factors for dementia based on gender, available data indicate that women in poor countries remain at a higher risk of developing the condition.

The finding of the study, published in the journal Alzheimer's & Dementia recently, researchers led by scientists from The George Institute for Global Health analysed data from 29,850 participants from 21 cohorts across six continents and found that women particularly from poorer countries were 10% more at the risk of developing dementia.

While previous research had shown women have a greater lifetime risk of developing dementia than men, partly because they tend to live longer, age alone may not fully account for this difference, says lead author of the study, Jessica Gong, a doctoral researcher from The George Institute for Global Health, said.

 “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,” she said.

 “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 available trends, cases of dementia are increasing most rapidly in low- and middle-income countries (LMICs) that are less able to manage the significant economic and societal impact of the devastating disease and the number of people living with dementia is projected to exceed 150 million by 2050 worldwide, three times the 2019 estimate of 50 million, the researchers noted.

It may be recalled that a Lancet Commission Report of 2020 estimated that as much as 40%  of dementia risk could be attributed to 12 modifiable risk factors, many of which are more common in LMICs, including less education, hypertension, obesity, diabetes, depression, hearing impairment, smoking, excessive alcohol consumption, physical inactivity, low social contact, traumatic brain injury, and air pollution.

“When we looked for sex differences in these 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,” Ms Gong said.

“While more years of education, higher hip circumference, current alcohol use (versus never drinking) and high physical activity (versus none to minimal activity) were associated with a lower risk of dementia in both sexes,” she added.

“But there was moderate evidence for a sex difference with years spent in education, indicating a stronger protective association for men than women.”

According to the authors, women, particularly in LMICs, have not had equal educational and occupational opportunities to men.

Furthermore, higher educational attainment and mentally stimulating occupations are protective against dementia, they argued.

Associate Professor Sanne Peters, a Senior Lecturer at The George Institute for Global Health UK in partnership with Imperial College London and part of the research team, said that institutional factors restricting women’s opportunities reduced access to appropriate healthcare and risk management programs, as well as other factors such as domestic violence, particularly for women from lower social and economic settings, can lead to psychological stress and leave them in worse financial positions, affecting their 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,” she said.

“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,” Professor Peters added.