City air harms the brain

Increased particulate matter pollution leads to shrinking brain volume and silent strokes

Diesel exhaust is one of the sources of particulate matter in the city. © Kichigin / thinkstock
Read out

More dementia due to fine dust? The typical city dust particulate matter also affects our brains: It increases the risk of silent brain infarction in the elderly and leads to a more shrinking brain, as a US study now shows. These effects of air pollution in turn can promote dementia, depression and cognitive deficits, as the researchers in the journal "Stroke" report.

It comes from diesel vehicles, coal-fired power plants and industrial plants, but also from the wood heaters and chimneys of residential buildings: fine dust. It has long been known that the tiny particles are detrimental to our health - in Europe alone, 150, 000 people die each year from fine dust-induced lung diseases, as recently reported in a recent study. The damage to health begins even at low concentrations below the limit.

Elissa Wilker from the Beth Israel Deaconess Medical Center in Boston and her colleagues have now investigated the effects of particulate matter pollution on the brain. They examined 900 over-60s who lived at different distances from major roads and were exposed to different levels of particulate matter contamination of 2.5 microns (PM 2.5). In brain scans, they determined the volume of individual brain areas and looked for evidence of blood clots and small brain infarcts.

Measurable damage even with a slight increase

In fact, the researchers found clear effects of particulate matter: the subjects who were exposed to higher levels of particulate matter had on average a smaller brain volume, signs of increased brain mass shrinkage and more so-called silent brain infarcts - small strokes that are not noticed by those affected,

As the scientists report, there was even a linear correlation between stress and consequences: For every increase in particulate matter pollution by two micrograms per cubic meter of air, the subjects had a 46 percent higher risk of silent strokes. Her brain volume also corresponded to that of a one year older man. The higher the load, the older the brain of the participants was. display

Increased risk of dementia

"That's worrisome, " says Wilker. "Because we know that silent heart attacks increase the risk of major strokes, but also for dementia, coordination problems and depression." As the study shows, is sufficient for the typical of most cities particulate matter load, accelerated aging of the brain and to cause silent infarcts.

It is still unclear what mechanisms of fine dust on the brain acts, as the researchers explain. However, they suspect that the tiny particles that are deposited in the lungs trigger a systemic inflammation that affects the entire body. In further investigations, they now want to investigate the effect of fine dust on the brain in more detail. (Stroke, 2015; doi: 10.1161 / STROKEAHA.114.008348)

(Beth Israel Deaconess Medical Center, 27.04.2015 - NPO)