Their research found a 70% increased risk of dementia for each unit increase in exposure to particulate matter less than 2.5 micrometers in size. This is the commonest form of pollution in urban environments. The groups found that about half of this increased risk was related to raised blood levels of homocysteine. Since homocysteine levels can be lowered by taking B vitamins, this suggests a way of reducing the harmful effect of pollution, although of course it would be better to avoid pollution in the first place. The paper is the outcome of a collaboration with the Karolinska Institute in Stockholm. The paper is free online at:
https://doi.org/10.1212/WNL.0000000000207656
A new study jointly published by Professors David Smith and Helga Refsum confirms that chronic exposure to air pollution in the elderly increases the risk of developing dementia a few years later.