92% of people live in places where particulate matter pollution exceeds the World Health Organization’s guideline for healthy air. The gene variant, which ~25% of people possess, ApoE4 increases the risk that exposure to air pollution leads to #Alzheimers. https://nyti.ms/2TjBgpL
Why Is Air Pollution So Harmful? DNA May Hold the Answer
It’s not just a modern problem. Airborne toxins are so pernicious that they may have shaped human evolution.
https://www.nytimes.com/2020/01/13/scie ... e=Homepage
But the researchers have studied another gene for which the opposite seems to be true: a variant that was once helpful has become harmful in an age of rising air pollution.
The variant, ApoE4, first came to light because it drastically raises the risk of developing Alzheimer’s disease. More recently, researchers have also discovered that ApoE4 increases the risk that exposure to air pollution leads to dementia.
But these studies were restricted to industrialized countries. When researchers looked to other societies — such as farmers in poor villages in Ghana, or indigenous forest-dwellers in Bolivia — ApoE4 had a very different effect.
In these societies, infectious diseases remain a major cause of death, especially in children. Researchers have found that in such places, ApoE4 increases the odds that people will survive to adulthood and have children.
Natural selection may have favored ApoE4 for hundreds of thousands of years because of this ability to increase survival. But this gene and others may have had harmful side effects that remained invisible until the sooty, smoky modern age.