Air Pollution Tied to Greater Amyloid Burden in the Brain

TOPLINE:

Exposure to more traffic-related air pollution is associated with greater levels of amyloid plaques in the brain, with exposure in the 3 years before death having the greatest risk, a new postmortem study showed.

METHODOLOGY:

• Investigators examined the brain tissue of 224 people living in the Atlanta area who agreed to donate their brains after death (average age of death, 76 years) for the presence of amyloid plaques and tau tangles.
• They also studied the amount of fine particulate matter < 2.5 microns (PM2.5) from traffic-related air pollution at participants’ home addresses at 1, 3, and 5 years before death.
• The presence of the APOE e4 gene was examined for evidence of any effect on the relationship between air pollution and evidence of Alzheimer’s disease (AD).

TAKEAWAY:

The average level of exposure in the year before death was 1.32 µg/m³ and 1.35 µg/m³ in the 3 years before death.

People with 1 µg/m³ higher PM2.5 exposure in the year before death were nearly twice as likely to have higher levels of plaques (odds ratio [OR], 1.92; 95% CI, 1.12-3.30), while those with higher exposure in the 3 years before death were 87% more likely to have higher levels of plaques (OR, 1.87; 95% CI, 1.01-3.17).

A little more than half (56%) of the sample were positive for the APOE e4 genotype, but the strongest association between pollution and neuropathology markers was for noncarriers of the genotype, although this relationship did not reach statistical significance.

IN PRACTICE:

“More research is needed to establish causality for the association between PM2.5 and AD, including epidemiologic and mechanistic studies. Future studies should also investigate the association between PM2.5 and other dementia-related pathologies, including cerebrovascular pathology,” the study authors wrote.

SOURCE:

Anke Hüls, PhD, of Emory University in Atlanta, led the study, which was published online on February 21, 2024, in Neurology.

LIMITATIONS:

The sample was not population-based but a convenience sample composed mostly of highly educated White participants.

DISCLOSURES:

The study was funded by the National Institute of Environmental Health Sciences, the Goizueta Alzheimer’s Disease Research Center, the National Institute on Aging, and the National Institutes of Health. There were no relevant disclosures.

A version of this article appeared on Medscape.com.