Car Emissions, Air Pollution Linked To Higher Dementia Risk: Study

Regular exposure to air pollution, including that coming from car exhaust emissions, can increased your risk of dementia, according to an analysis of studies published on Friday.

Dementias such as Alzheimer's disease are estimated to affect more than 57.4 million people worldwide, a number that is expected to almost triple to 152.8 million cases by 2050.

The study, published in the journal The Lancet Planetary Health, showed that for every 10 micrograms per cubic metre of PM2.5, an individual's relative risk of dementia would increase by 17 per cent.

For each 1 micrograms per cubic metre of soot as found in PM2.5, the relative risk for the cognitive condition increased by 13 per cent. Soot comes from sources such as vehicle exhaust emissions and burning wood.

"These findings underscore the need for an interdisciplinary approach to dementia prevention. Preventing dementia is not just the responsibility of health care: this study strengthens the case that urban planning, transport policy, and environmental regulation all have a significant role to play," said joint first author Dr. Christiaan Bredell from the University of Cambridge.

Air pollution causes inflammation in the brain and oxidative stress (a chemical process in the body that can cause damage to cells, proteins, and DNA), leading to the onset and progression of dementia.

"Tackling air pollution can deliver long-term health, social, climate, and economic benefits. It can reduce the immense burden on patients, families, and caregivers, while easing pressure on overstretched health care systems," said Dr. Haneen Khreis from the MRC Epidemiology Unit.

For the study, the team carried out a systematic review and meta-analysis of existing scientific literature. They included 51 studies, including data from more than 29 million participants, mostly from high-income countries. Of these, 34 papers were included in the meta-analysis: 15 originated in North America, 10 in Europe, seven in Asia, and two in Australia.

The researchers found a positive and statistically significant association between particulate matter with a diameter of 2.5 microns or less (PM2.5), Nitrogen dioxide (NO2), and soot and dementia.

Further analysis revealed that the effect of exposure to these pollutants was stronger for vascular dementia -- a type of dementia caused by reduced blood flow to the brain.

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