Specific amino acids can alter the risk of dementia associated with air pollution

Higher levels of vitamin B-related amino acids may be linked to the risk of dementia associated with a certain type of air pollutants called particulate matter, according to a study published in the online issue of Neurology. The study does not prove that pollution or amino acids cause dementia, but it suggests a possible link among them.

Researchers looked at fine particulate matter, PM2.5, which consists of pollutant particles of less than 2.5 microns in diameter suspended in air. They also looked at two amino acids, methionine and homocysteine. Methionine is an essential amino acid found in foods such as meat, fish, dairy, beans and eggs and is involved in normal brain functions. Homocysteine is an amino acid produced in the cells that can be transformed to methionine through a reaction that requires both vitamin B12 and folate, a nutrient important in red blood cell formation and for healthy cell growth and function.

For the study, over 2,500 adults with an average age of 73 living in central Stockholm were followed for up to 12 years. Of these, 376 people developed dementia. After adjusting for several factors that affect a person’s risk of dementia including age, sex, smoking, and education, researchers found that the risk of dementia increased by 70% for every one µg/m3 increase of PM2.5 exposure during the five years before the start of the study.

Then researchers looked at whether the impact of air pollution exposure on dementia was affected by the amino acids. Overall, researchers found that about half of the increased risk of dementia due to PM2.5 was due to an interaction between air pollution and high homocysteine levels or low methionine levels.

Reference: Giulia Grande et al,Neurology