Study warns: The risk of dementia increases even with low fine dust values

Particulate matter has long been suspected of increasing the risk of dementia. one in „British Medical Journal“ (BMJ) published analysis of 16 studies confirms this connection: Accordingly, particle concentrations well below the limit values ​​applicable in the EU also increase the risk of illness. According to a comment in the journal, the study underlines the urgency of reducing air pollution worldwide through political measures.

57 million people have dementia

More than 57 million people worldwide are living with dementia, and the number is rising, writes Marc Weisskopf’s team at Harvard University in Boston. The neurodegenerative disease, which also includes Alzheimer’s syndrome, cannot be cured. There has long been a suspicion that air pollution increases the risk of illness – in particular exposure to small fine dust particles with a diameter of up to 2.5 micrometers (thousandths of a millimeter; PM2.5).

To test this connection, the team evaluated 16 studies, mostly from North America and Europe.

• Nine of these had a more modern methodology, not just matching information from datasets, but actively examining the participants.
• 14 studies focused on fine dust particles of the size PM2.5, several also on various nitrogen oxides and ozone (O3).

The evaluated studies found a higher risk of disease with increasing exposure to particulate matter. On average, this hazard increased by four percent with an increase in the average annual PM2.5 concentration of two micrograms per cubic meter. In those studies in which the participants were actively examined, the risk per two micrograms per cubic meter even increased by an average of 42 percent. The study also found a connection to the risk of dementia – based on smaller data – for nitrogen oxides, but not for higher ozone values.

Particulate matter is questionable even below the limit values

The authors admit that their study cannot prove that particulate matter actually contributes to dementia. However, they emphasize that the results strengthen the suspicion that particulate matter is already a concern below the usual limit values. The PM2.5 limit is an annual mean of 12 micrograms per cubic meter in the US, 20 micrograms per cubic meter in the UK and 25 micrograms per cubic meter in the EU.

Particulate matter is caused, among other things, in traffic by combustion engines, but also by tire abrasion. Other sources include industry, power plants and wood stoves. The determined effect of air pollution on the risk of dementia is lower than that of smoking – because cigarette smoke also contains fine dust. However, given the sheer number of people who are exposed to high levels of stress, the consequences at the population level are substantial, the group writes.

Several biological connections could explain the effect of fine dust on dementia, it is said. Fine dust is known to damage the cardiovascular system, and cardiovascular problems are considered risk factors for dementia. In addition, particulate matter can damage the blood-brain barrier and promote inflammatory reactions in the brain, even leading to the death of nerve cells. However, the team emphasizes that it is difficult to prove that such mechanisms are involved in dementia in humans.

Air pollution has other health consequences

In a “BMJ” comment, Andrew Sommerlad and Kathy Liu from University College London refer to the drastic differences in particulate matter pollution in different cities: the annual mean value for PM2.5 in Toronto is below 10 micrograms per cubic meter, in some cities such as Delhi it more than 100 micrograms. There are hardly any studies from those regions in Africa and Asia where fine dust pollution is particularly high.

“Air pollution is also associated with other health outcomes and mortality,” Sommerlad and Liu write. They cite an estimate that bad air is responsible for more than 6.5 million deaths each year. About 40 percent of all countries have no regulations on air quality, the doctors complain and refer to the goal of the World Health Organization (WHO) to target fine dust concentrations below five micrograms per cubic meter.

“Any positive impact on dementia and general health would be accompanied by an important effect on climate change and biodiversity,” the commentary continues. According to estimates, more than 1.4 million people in Germany are affected by dementia.

How to prevent dementia

There is no cure for the disease. But studies suggest that we can do something against the slow decline in our brain power. Not only with classic brain jogging, but also with a healthy diet and sufficient exercise keep our brain cells fit. Among other things, one came to this conclusion Study by Finnish researchers.

The scientists identified four practices that protect our brains:

1. Eat healthy

Nutrition experts recommend the so-called Mediterranean diet with lots of fresh vegetables, nuts, fish and olive oil.

2. Exercise regularly

Fitness expert Ingo Froböse recommends three exercises with which you can train your whole body in just ten minutes every day.

3. Maintain social contacts

Friendships not only make you happy, according to scientists they also have a positive effect on our brain.

4. Challenge your brain

Learn your shopping list by heart and keep it in your pocket as a cheat sheet. Regularly solve a riddle online or in a book and do simple calculations in your head instead of using a mobile app or calculator.