A new study from Emory University indicates that people exposed to higher levels of air pollution have an increased risk of developing Alzheimer's disease. The research, led by Yanling Deng and colleagues, was published on February 17 in the journal PLOS Medicine.
The study focused on more than 27.8 million Medicare recipients in the United States who were aged 65 and older between 2000 and 2018. Researchers examined participants' exposure to air pollution and tracked the onset of Alzheimer's disease, paying particular attention to other chronic health conditions such as hypertension, stroke, and depression.
The results showed a clear association between greater exposure to air pollution and a higher risk of Alzheimer's disease. The link was slightly stronger among individuals who had previously experienced a stroke. In contrast, hypertension and depression did not appear to significantly increase the effect of air pollution on the risk of developing Alzheimer's disease.
The findings suggest that air pollution contributes to Alzheimer's disease mainly through direct effects on the brain rather than indirectly through chronic health conditions. However, those with a history of stroke may be especially vulnerable.
"In this large national study of older adults, we found that long-term exposure to fine particulate air pollution was associated with a higher risk of Alzheimer's disease, largely through direct effects on the brain rather than through common chronic conditions such as hypertension, stroke, or depression," the authors stated.
They added: "Our findings suggest that individuals with a history of stroke may be particularly vulnerable to the harmful effects of air pollution on brain health, highlighting an important intersection between environmental and vascular risk factors."
These results indicate that efforts to improve air quality could play an important role in preventing dementia among older adults.
