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TOPLINE:

A study found that long-term exposure to particulate matter of diameter ≤ 2.5 μm (PM2.5) in air, even at relatively low levels, was associated with structural changes in the brain such as reduced brain tissue volume, increased atrophy, and increased vascular pathology among older adults.

METHODOLOGY:

• The SNAC-K-MRI study included older adults without dementia who underwent MRI of the brain at baseline. Additionally, cohorts younger than 78 years underwent brain MRI after 6 years, whereas those aged 78 years or older underwent it after 3 and 6 years.
• For 457 participants (mean age, 70 years; 41% men), the total brain tissue volume (TBTV) and volumes of ventricles, hippocampus, and white matter hyperintensities (WMHs) were assessed.
• Researchers evaluated participants' exposure to PM2.5 and PM10 between 1990 and 2010 on the basis of their residential addresses.
• The analysis was controlled for age, sex, educational level, smoking, socioeconomic status, and neighbourhood household mean income.

TAKEAWAY:

• Compared with participants exposed to lower levels of PM2.5 and PM10, those exposed to PM2.5 levels above 8.5 μg/m³ and PM10 levels above 14.9 μg/m³ showed a reduced TBTV (β, −0.20; 95% CI, −0.33 to −0.06 and β, −0.14; 95% CI, −0.27 to −0.01, respectively).
• Compared with participants exposed to PM2.5 levels < 8.7 μg/m³, those exposed to PM2.5 levels > 8.7 μg/m³ during the follow-up period had increased annual TBTV shrinkage (β, −0.22; 95% CI, −0.44 to −0.01) and increased annual WMHs (β, 0.25; 95% CI, 0.07-0.43).
• No significant associations were found between exposure to PM2.5 and PM10 and annual changes in other brain volumes.

IN PRACTICE:

"Our study revealed that older adults exposed to high levels of PM2.5 exhibited smaller total brain tissue volumes, more global atrophy, and a higher accumulation of vascular pathology over time," the authors wrote.

They noted that these changes were evident even among "individuals free from dementia and cerebrovascular diseases" and in "a study area with historically low concentrations of air pollution."

SOURCE:

This study was led by Giulia Grande, MD, PhD, Care Sciences and Society, Karolinska Institutet and Stockholm University, Stockholm, Sweden. It was published online on May 12 in Stroke.

LIMITATIONS:

This study was limited by a small sample size. The study primarily included healthy, high socioeconomic status older adults in central Stockholm, limiting its generalisability. Additionally, the small geographic area reduced variation in pollution levels, and key neuroimaging markers such as microbleeds and amyloid deposition were not included.

DISCLOSURES:

This study was supported by the Karolinska Institutet Fonder, Demensfonden, and Foundation for Geriatric Diseases at Karolinska Institutet. The authors reported having no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.