Older adults who are exposed to higher levels of air pollution appear more likely to develop Alzheimer’s disease, according to new research led by Yanling Deng of Emory University.

Alzheimer’s disease is the leading cause of dementia, affecting an estimated 57 million people worldwide. Air pollution has already been identified as a risk factor not only for Alzheimer’s, but also for several chronic conditions, including hypertension, stroke, and depression. These same health problems are also associated with dementia. Until now, however, scientists were unsure whether polluted air increases dementia risk by first contributing to these chronic illnesses, or whether those illnesses simply make the brain more vulnerable to pollution’s effects.

Massive Medicare Study Examines 27.8 Million Older Adults
To investigate, researchers analyzed data from more than 27.8 million U.S. Medicare beneficiaries age 65 and older between 2000 and 2018. They compared long term exposure to air pollution with new diagnoses of Alzheimer’s disease, while also examining whether conditions such as stroke, hypertension, and depression influenced the relationship.

The results showed a clear pattern. Higher exposure to air pollution was linked to a greater risk of developing Alzheimer’s disease. The association was somewhat stronger among individuals who had previously experienced a stroke. In contrast, hypertension and depression did not appear to significantly intensify the pollution-related risk.