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”.

The findings were published on Thursday as an open access paper in The Lancet.

Not all countries are equal

Dementia cases will rise in every country,  but the trend isn’t equally spread.

The smallest estimated increases are in high-income Asia Pacific (53 per cent) and western Europe (74 per cent), and the largest growth in north Africa and the Middle East (367 per cent) and eastern sub-Saharan Africa (357 per cent).

Australia will more than double its dementia population – from 348,673 in 2019, to 796,702 in 2050.

(Dementia.org.au, quoting 2022 Dementia Australia Prevalence Data, says there is now an estimated 487,500 people living with all forms of dementia.)

The biggest upward swing will happen in Qatar – where the dementia population will become 20 times bigger (1926 per cent).

The United Arab Emirates isn’t far behind, with an increase of 1795 per cent. Bahrain (1084 per cent), Oman (943 per cent) and Saudi Arabia (898 per cent) round out the top five.

Japan (27 per cent), Bulgaria (37 per cent), Serbia (38 per cent), Lithuania (44 per cent) and Greece (45 per cent) will have the lowest rates of growth.

Some nuance and risk factors

The researchers found that improvements in global education access are projected to reduce dementia prevalence by 6.2 million cases worldwide by 2050.

But this will be countered by “anticipated trends in obesity, high blood sugar, and smoking, which are expected to result in an additional 6.8 million dementia cases”.

The authors call “for more aggressive prevention efforts to reduce dementia risk through lifestyle factors, such as education, diet, and exercise, as well as by expanding much-needed health and social care resources”.

Are these ‘apocalyptic predictions’?

The research was led by Dr Emma Nichols from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington.

“These estimates can be used by national governments to make sure resources and support are available for individuals, caregivers, and health systems globally,” she said.

Writing in a linked comment piece, Dr Michaël Schwarzinger and Dr Carole Dufouil, Bordeaux University Hospital in France, said the research oversimplified “the underlying mechanisms that cause dementia … [they] provide apocalyptic projections that do not factor in advisable changes in lifestyle over the lifetime”.

They noted: “There is a considerable and urgent need to reinforce a public health approach towards dementia to better inform the people and decision makers about the appropriate means to delay or avoid these dire projections.”

That is certainly true. But health writers and public health educators urge a healthy change in lifestyle every day. Little of it seems to stick when it comes to changing hard-to-break, long-held habits.