Investigating effects of air quality and weather on human brain volumes

Understanding the environmental factors that influence brain health is crucial for public health and neuroscience research. Recent studies have separately investigated associations between weather, seasonality, and air quality on brain volumes and functional brain connectivity. However, air quality and weather are interrelated factors. Therefore, it is important that we investigate the effect of their combined interaction with human brain volumes. In this study, we aligned volumetric brain data from structural MRI scans acquired from kids aged between 5 and 10 to hourly air quality and weather data. We used multiple linear regression models with age, sex, date, hour, air quality, and weather to predict total brain volumes. The total brain volumes used to train and test our model were acquired from T1-weighted MRI using FreeSurfer. Select weather variables such as hourly dew point temperature and hourly relative humidity were positively associated with brain volume (p < 0.01). Although not statistically significant, hourly wet bulb temperature suggested a modest influence on brain volume. None of the air quality variables showed significant associations. These findings underscore the importance of considering a broad range of environmental factors in neuroimaging studies and suggest that air quality and seasonal influences can be confounds in studies investigating variations in structural brain volumes.