Scientists from the Karolinska Institute have found that higher levels of certain amino acids may be associated with an increased risk of dementia associated with particulate air pollutants. The research was published in the journal neurology.
Previous research has found a link between airborne PM2.5 particulate matter (less than 2.5 microns in diameter) and the risk of dementia. But scientists still don’t have a clear understanding of how air pollution affects the brain.
The new study included more than 2,500 adults with an average age of 73 living in central Stockholm. They were followed for 12 years, during which 376 people developed dementia.
Healthy and demented people had approximately the same average annual PM2.5 particle exposure: 8.3 µg/m3 and 8.4 µg/m3 respectively.
After adjusting for various factors that affect dementia risk (age, gender, smoking status, and education), the researchers found that the risk of developing dementia increased by 70% for each additional µg/m3 increase in PM2.5 exposure.
About half of this effect was due to either high homocysteine levels or low methionine levels. Methionine is an essential amino acid found in meat, fish, eggs, beans and dairy products that is essential for brain function. Homocysteine is an amino acid produced in human cells that can be converted to methionine by a reaction that requires vitamin B12 and folic acid.
The results could mean that air pollution affects the risk of dementia in more ways than one. The study doesn’t prove that environmental pollution or the amino acids studied cause dementia, but suggests a possible link between them.
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