Paris (AFP)

About 40% of dementia cases could be prevented or delayed by reducing a dozen risk factors, including excessive alcohol consumption, smoking, head shocks and air pollution, according to a report released Thursday. .

Its authors, a group of experts, therefore formulate a series of recommendations to political decision-makers, including limiting alcohol consumption, stopping tobacco consumption, reducing obesity and diabetes or reducing exposure to air pollution. 'air.

"Our report shows that policymakers and individuals have the power to prevent or delay a significant proportion of dementia cases," said lead author Prof. Gill Livingston of University College London, quoted in a press release from the medical journal The Lancet, which publishes the report.

"These actions are likely to have the biggest impact on those who are disproportionately affected by risk factors for dementia, such as people in low and middle income countries and vulnerable populations, including ethnic minorities," continued -she.

According to the WHO (World Health Organization), 50 million people are affected by dementia worldwide, with 60 to 70% of cases caused by Alzheimer's disease. This number tends to increase as we live longer and longer.

WHO estimates that the total number of people with dementia is expected to climb to 82 million in 2030 and 152 million by 2050, largely due to the increase in the number of cases in low- and middle-income countries.

Caused "by a set of diseases and trauma" that affect the brain, dementia "affects memory, reasoning, orientation, comprehension, calculation, learning ability, language and judgment", recalls WHO on its website.

- The egg or the chicken? -

In a previous report, published in 2017 by The Lancet, the same researchers had already identified nine risk factors.

They updated this list to add three: excessive alcohol consumption, head injuries and exposure to air pollution in adulthood.

According to them, these factors are respectively associated with 1%, 3% and 2% of cases of dementia. The other factors are education conditions (7%), hearing loss (8%), hypertension (2%), obesity (1%), smoking (5%), depression ( 4%), social isolation (4%), physical inactivity (2%) and diabetes (1%).

However, other scientists who did not participate in the study stress that if these risk factors are associated with dementia, it should not be deduced that they are the cause.

"This leaves a large number of questions of the type + which is the first, the egg or the chicken +", underlines Professor Tara Spiers-Jones, specialist in brain and dementia at the University of Edinburgh ( Scotland).

"For example, depression over 65 is associated with a risk of dementia, but this type of data does not allow us to say whether it is the first that contributes to causing the second, since there is also evidence that Changes in the brain in the early stages of dementia are causes of depression, ”she details.

"This report estimates that 40% of dementias could be preventable with lifestyle changes, which means that 60% are, as far as we know, caused by things we cannot control, such as genetic factors, ”she continues.

"I hope this report doesn't lead people to think it's their fault that they are suffering from depression," she insists.

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