There are also studies hinting at a potential pathway involved in this: exposure to particulate air pollution appears to reduce the activity of brain-derived ne

There are also studies hinting at a potential pathway involved in this: exposure to particulate air pollution appears to reduce the activity of brain-derived neurotrophic factor (BDNF). [1] [2] [1] https://www.ncbi.nlm.nih.gov/pubmed/21708224 https://www.ncbi.nlm.nih.gov/pubmed/21708224 [2] https://www.ncbi.nlm.nih.gov/pubmed/25816123 https://www.ncbi.nlm.nih.gov/pubmed/25816123