Exposure to Ambient Temperature and Functional Connectivity of Brain Resting-State Networks in Preadolescents.

OBJECTIVE

Exposure to extreme temperatures has been linked to acute mental health events in young populations, but the underlying neural mechanisms are not well understood. Resting-state functional magnetic resonance imaging allows for the assessment of connectivity patterns in brain functional networks, which have been associated with mental health disorders. This study investigated the short-term effects of ambient temperature on functional connectivity of brain resting-state networks in preadolescents.

METHOD

The study was embedded in the Generation R Study, Rotterdam, the Netherlands. Daily mean temperature estimates at the residential addresses of participants were obtained from a high-resolution urban climate model (UrbClim). Resting-state functional connectivity data were assessed with brain magnetic resonance images of 2,229 children ages 9 to 12 years. Distributed lag nonlinear models were fitted to assess the cumulative effects of temperature during the week before the brain scan on within- and between-network connectivity of 15 resting-state networks.

RESULTS

Higher ambient temperature during the week before the imaging assessment was associated with lower functional connectivity within the medial parietal, salience, and hippocampus networks. The effect was highest the day before the brain scan and progressively decayed in the preceding days. Lower temperatures were not related to functional connectivity.

CONCLUSION

Exposure to high ambient temperatures over a 7-day period was associated with lower within-network connectivity in preadolescents, suggesting impacts of heat on brain function. These findings raise new research questions on whether decreases in functional connectivity within the salience network may partially explain the association between high temperatures and suicide rates previously reported in the literature.