New research: Why more women than men get dementia

A large new study from the George Institute for Global Health suggests that lack of education may account for why more women end up with dementia than men.

The study focuses on women in poorer countries where the likelihood of developing dementia is more pronounced.

But there are implications for Australians.

Why education is vital

Education is known to be protective against developing dementia, but how this happens isn’t fully understood. One idea is that education and working at a job that challenges the mind causes the brain to build more synapses or connections.

As we reported in January, education is one of the keys to building cognitive reserve, which serves as a buffer against loss of function in people with brain damage.

That is, cognitive reserve enables the brain to continue working well, even when it’s been damaged.

However, according to the OECD, 40 to 50 per cent of adults in Australia have literacy levels below the international standard required for participation in work, education and society.

A parliamentary inquiry is looking at how to improve literacy levels in Australia.

These deficits presumably limit the ability of the brain to develop cognitive reserve.

Women and dementia

Nearly two-thirds of people living with dementia in Australia are women.

That ratio appears to hold worldwide: Wherever you go, twice as many women have dementia than men.

A common explanation for this is that women live longer than men.

Women live longer than men, and tend to suffer more social isolation in old age. Photo: Getty

The thinking is that with men dying faster, this leaves more women alive with the disease.

If only men lived longer, the numbers would balance out, the argument goes.

The problem is, while dementia is the second-leading cause of death for Australians, dementia is what kills most women.

So something else must be going on in women that doesn’t happen in men.

The possibilities

Because the higher risk for women appears to hold constant, the temptation is to conclude that one single factor is to blame.

In March last year we reported on a study that found hormonal changes in the brain caused by menopause could be triggering dementia.

Research suggests that menopause triggers dementia pathologies in the brain. Photo: Getty

Another possibility that demands further investigation is social isolation  – which is associated with about a 50 per cent increased risk of dementia.

Men tend to suffer more social isolation than women for most of the life course. But this changes as people age and men die off.

Loneliness becomes more common in older women, in particular those with less education and lower wealth.

Where we’re headed

The number of adults – aged 40 years and older – living with dementia worldwide is expected to nearly triple globally in less than 20 years.

This is the prediction of a Global Burden of Disease study, the first to provide forecasting estimates for 204 countries worldwide.

By 2050, 153 million people are expected to be living with dementia worldwide, up from 57 million in 2019.

This will be due primarily to population growth and population ageing.

But the researchers analysed four main risk factors – obesity, high blood sugar, smoking and low education – and their “impact on future trends”.

These factors will especially come to bear in poorer countries.

The new study

The George Institute researchers examined dementia risk in almost 30,000 people from 18 countries covering all six continents.

When adjusted for age, rates of dementia were “highest among low to lower-middle-income countries”. And they “were higher in women than in men”.

Equality in education makes for a more secure, healthier society. Photo: Getty

This finding is supported by previous research.

Lead author Jessica Gong said that most research estimating dementia incidence has been conducted in high-income countries.

She said there was, to date, very little data available in the countries “that actually bear the greatest burden”.

A universal problem

Of course, western countries have plenty of poorly educated and isolated people with relatively few resources.

As Ms Gong told The New Daily: Socioeconomic factors are equally important determinants of dementia risk in western countries.

“Social and economic factors clearly play a significant part in determining one’s health level, in high-income as well as lower-middle income countries.

“Gender gaps still exist in socioeconomic factors including education, income, workforce and familial roles which create health disparities, to women’s disadvantage.”

How education was arrived at

The researchers starting point was the 2020 Lancet Commission Report that suggested as much as 40 per cent of dementia risk could be attributed to 12 modifiable risk factors.

In other words, these factors were behaviours and exposures that could be potentially changed by an individual.

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

In the new study, when the researchers looked for sex differences in these risk factors. But they found that many were associated with a greater risk of dementia in both men and women.

These included older age, diabetes, depression, hearing impairment and having a certain genetic variation involved in fat metabolism in the brain – known as APOE4.

However, they found “moderate evidence for a sex difference with years spent in education”.

This indicated “a stronger protective association for men than women”.

The authors argued that women, particularly in low- to middle-income countries, “have not had equal educational and occupational opportunities to men”.

They note that “higher educational attainment and mentally stimulating occupations have been shown to be protective against dementia”.

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