Public Health

Area of Science:

• Neuroscience
• Environmental Health
• Radiology

Background:

• Exposure to fine particulate matter (PM2.5) is a known risk factor for accelerated brain aging and dementia.
• Understanding the impact of PM2.5 on specific brain structures like cortical thickness is crucial for public health.

Purpose of the Study:

• To investigate the association between residential PM2.5 exposure and regional cortical thickness (CTh) across diverse international datasets.
• To explore how age and sex modify the relationship between PM2.5 exposure and CTh.

Main Methods:

• Utilized data from 2,086 adults across seven international cohorts.
• Assessed PM2.5 exposure using satellite-based estimates averaged over three years prior to MRI.
• Employed linear mixed models to analyze associations between PM2.5 and CTh, adjusting for multiple covariates and including cohort/scanner as random effects.

Main Results:

• PM2.5 exposure showed an inverse association with CTh in the superior temporal gyrus (STG) among cognitively unimpaired controls.
• A significant quadratic effect of PM2.5 on CTh was observed across the lifespan, with different associations at younger, midlife, and older ages.
• Sex-specific interactions revealed that PM2.5 was inversely associated with CTh in males but not females in several frontal regions.

Conclusions:

• PM2.5 exposure is specifically associated with reduced CTh in the STG of healthy older adults.
• The quadratic age-by-exposure interaction suggests a complex, potentially biphasic neurodegenerative process related to air pollution.
• Observed sex differences in PM2.5 effects on CTh warrant further investigation into potential interactions with sexual dimorphism and air pollution.