The cognitive toll of household air pollution: cross-sectional associations between polluting cooking fuel use, cognitive functions and brain MRI in a rural aging population from Karnataka, India.

BACKGROUND

Household air pollution (HAP) from polluting cooking fuels, a rampant issue in rural India, is suspected to be a significant modifiable risk factor for cognitive impairment; however, evidence supported by neuroimaging in this population, is lacking.

METHODS

Baseline cross-sectional data (n = 4145) of participants aged ≥45 years from the ongoing Centre for Brain Research-Srinivaspura Aging, Neuro Senescence, and COGnition (CBR-SANSCOG) study in a rural South Indian aging population, was utilised. HAP exposure was proxied via polluting cooking fuel or technology use (only clean vs. at least one polluting vs. only polluting cooking technology use). Global and domain-specific cognitive functioning was assessed using computerised culturally adapted test batteries. A subset (n = 994) underwent brain MRI (3T) to estimate regional brain volumes and white matter hyperintensities (WMHs) burden. Fully adjusted linear regression models were used to test the associations between HAP exposure, cognition, and brain MRI parameters.

FINDINGS

Only polluting cooking technology users had significantly lower scores in global cognition (β = -0.28 [-0.44, -0.11], p [FDR corrected p-value] = 0.002), visuospatial ability (β = -0.28 [-0.48, -0.08], p = 0.013), and executive functions (β = -0.25 [-0.44, -0.07], p = 0.019), whereas at least one polluting cooking technology users had lower scores in global cognition only (β = -0.10 [-0.15, -0.04], p <0.001), compared to the clean cooking technology users. Upon sex-stratification, only female polluting cooking technology users had lower global cognitive scores (β = -0.11 [-0.20, -0.03], p = 0.018) and lower hippocampus volumes (β = -0.18 [-0.35, -0.01], p = 0.030).

INTERPRETATION

Polluting cooking technology users may be at a higher risk for cognitive impairment. Rural females, who tend to be more exposed than males, could have greater vulnerability to HAP's adverse effects on the brain. Policies promoting clean cooking fuel/technology adoption are imperative.

FUNDING

CBR-SANSCOG study is funded by the Centre for Brain Research, India.