Air pollution raises the risk of dementia by 92% because toxic particles cause the brain to swell (and women are most at risk)

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Invisible particles in the air we breathe may elevate the risk of dementia by 92 per cent, experts have warned.

Toxic fumes from cars and power plants are infiltrating brain cells, causing them to swell in response.

This leaves the brain at risk of succumbing to the devastating condition, according to a new study.

Experts believe that dangerous levels of pollution in cities could actually be responsible for a fifth of global dementia cases. 

And scientists also discovered the risk was greater for women - especially if they possess a well-known 'dementia gene'.  

Toxic fumes from cars and power plants are infiltrating brain cells and increasing the risk of dementia, experts have warned

Researchers from the University of Southern California analysed data of 3,647 women between 65 to 79 who didn't have dementia.

'Microscopic particles generated by fossil fuels get into our body directly through the nose into the brain,' said study co-author Professor Caleb Finch.

'Cells in the brain treat these particles as invaders and react with inflammatory responses, which over the course of time, appear to exacerbate and promote Alzheimer's disease.

'Although the link between air pollution and Alzheimer's disease is a new scientific frontier, we now have evidence that air pollution, like tobacco, is dangerous to the aging brain.'

The study, which was published in the Translational Psychiatry journal, is the first of its kind conducted in the US.

It noted that women who live in heavily polluted areas - such as near main roads or busy city centres are 81 per cent more at risk for cognitive decline.

Theory: According to the data, pollution could be responsible for a fifth of dementia cases

While they are also 92 per cent more likely to develop dementia if they are exposed to levels deemed unsafe by health officials. 

And it also found that women with the APOE4 gene - a variation that increases the risk of Alzheimer's - were most at risk.  

Worldwide, nearly 48 million people suffer from dementia, and there are 7.7 million new cases every year, according to the World Health Organization.  

Earlier this year, scientists in Canada found that living close to a busy road increases the risk of Alzheimer's by up to 12 per cent.

They tracked the progress of six million adults for 11 years found a clear trend with dementia incidence rising the nearer people lived to main roads.

Compared with those whose homes were more than 300 metres away, people living within 50 metres of heavy traffic had a 7 per cent higher risk of developing dementia.  

While Danish researchers earlier this year found expectant mothers living close to busy roads are at greater risk of serious complications in pregnancy.

Pre-eclampsia – a condition suffered by 42,000 pregnant women in Britain each year – is made more likely by noise and pollution from roads.