Can Air Pollution Cause Alzheimer’s?
A new study has reported a correlation between living in polluted air and the likelihood of developing Alzheimer’s. The study data showed that older women who lived in areas where the air quality exceeded EPA limits for small particulate were twice as likely to develop cognitive impairment. Further, women who carry the APOE 4 gene, which predisposes them to Alzheimer’s, were three times as likely to develop Alzheimer’s. When extrapolated to the general population, air pollution could account for 21% of all cases of Alzheimer’s.
Researchers at University of Southern California conducted the study, published in Translational Psychiatry. It followed 3,674 women who were part of the Women’s Health Initiative Memory Study. They lived in 48 states and ranged in age from 65 to 79.
The study followed these women for 11 years, and gave them memory tests every two years. The researchers collected air pollution data for the areas in which these women lived, using the EPA cut off for fine particulate matter, molecules that are 2.5 micrometers or less in size. Such particulate is generated by vehicle emissions and coal fired plants.
In addition, the researchers studied female mice populations exposed to air with high levels of small particulate for 15 weeks. Those results confirmed that exposure to the air pollution resulted in accumulations of the protein ABeta in the mice brains. Changes to the size of the hippocampus area of the mice brains were also observed.
This study’s results confirm previous smaller studies that noted an association between air pollution and Alzheimer’s . It opens up a new area of research for those seeking to prevent Alzheimer’s.
It also raises a number of new questions:
- Does the composition of the small particulate matter, or does the small size alone create the inflammation?
- Are men as susceptible as women to the effects of air pollution?
- What implications does this study have on proposals to roll back EPA regulations?
- What are the implications for the developing world, notably China and India, where air pollution is a significant problem?
- Is the overall improvement in air quality a reason for the overall reduction in the incidence of Alzheimer’s in developed countries?
Even though there are many unanswered questions, it is a hopeful development that we might be able to significantly reduce or delay the onset of Alzheimer’s by protecting air quality.