A wide-ranging analysis, drawing from data on nearly 30 million people, finds a link between air pollution and dementia.
Studies have long shown that air pollution is a risk factor for dementia, but findings were sometimes contradictory and far from conclusive. To separate the signal from the noise, scientists analyzed data from 51 prior studies, largely from wealthy countries. They found an association between dementia and soot, particulates, and nitrogen dioxide.
Cars and trucks are a key source of all three pollutants. In Central London, particulate levels are high enough to raise the risk of dementia by 17 percent, according to the research, published in The Lancet Planetary Health. Soot poses a similar risk to Londoners.
Scientists say that pollution can enter the body through the lungs and then spread to the brain via the bloodstream. Pollutants may spur dementia by driving up inflammation and by damaging brain cells. While the study found an association between air pollution and Alzheimer’s disease, the link was stronger for vascular dementia, which is caused by low blood flow to the brain.
Close to 60 million people suffer from dementia worldwide. While the prevalence is declining in Europe and North America, it is set to rise across the Global South as populations age.
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