A study by the Barcelona Institute for Global Health has highlighted the vulnerability of fetuses and children to exposure to extreme temperatures, whether hot or cold. The results emphasize the need to protect the most vulnerable communities from the impacts of climate change.
Brain scans of over 2,000 preschool children show that early exposure to cold and heat can have a lasting impact on the microstructure of the brain’s white matter, particularly in children living in disadvantaged areas.
A study published in the journal Nature Climate Change highlights the sensitivity of fetuses and children to extreme temperatures. Another study conducted by ISGlobal and IDIBELL in collaboration with the Erasmus University Medical Center in Rotterdam emphasizes that the impact of extreme temperatures on human health is a deep concern for scientists and society.
Children are especially sensitive to temperature changes because their thermoregulation mechanisms are still immature. Monika Gouksens, a researcher at ISGlobal, notes that the developing brains of fetuses and children are particularly vulnerable to environmental influences and that exposure to cold and heat can affect the mental health and cognitive abilities of children.
In this study, Gouksens’ team analyzed the structure of white matter in the brains of adolescents to identify windows of sensitivity to cold and heat during the first years of life. The analysis included 2,681 girls and boys from the Generation R study, a birth cohort from Rotterdam who underwent magnetic resonance imaging (MRI) between the ages of 9 and 12 years. The study assessed brain connectivity by measuring the amount and direction of water diffusion in the white matter of the brain.
The research team used advanced statistical methods to evaluate each participant’s exposure to average monthly temperatures from conception to age 8 and its impact on MRI connectivity parameters. The results show that cold exposure during pregnancy and the first year of life, as well as heat exposure from birth to 3 years of age, are associated with greater mean diffusivity during prepuberty, indicating slower white matter maturation.
White matter fibers are responsible for connecting different regions of the brain, allowing communication between them. As white matter develops, communication becomes faster and more efficient. The study found that participants most exposed to extreme hot and cold temperatures showed differences in one parameter, mean diffusivity, which is associated with a lower level of white matter maturity.
The greatest changes in connectivity parameters are observed during the first years of life, suggesting that during this period of rapid brain development, exposure to extreme temperatures, whether hot or cold, may have lasting effects on white matter microstructure.
The team found no relationship between early temperature exposure and fractional anisotropy between ages 9 and 12 years. They suggest that one possible explanation is that these two measures reflect different microstructural changes, meaning that diffusivity may be a stronger indicator of white matter maturation than fractional anisotropy.
The study also found that girls and boys living in poor areas are more susceptible to extreme temperatures. The timing of susceptibility was similar to that of the overall cohort, but started earlier. These differences may be related to housing conditions and energy poverty.
An important mechanism that may explain the influence of environmental temperature on the development of the nervous system may be related to decreased sleep quality. Other mechanisms may include changes in placental function, activation of the endocrine axis leading to increased cortisol production, or inflammation.
The findings raise awareness about the sensitivity of fetuses and newborns to temperature changes and highlight the need to develop public health strategies to protect the most vulnerable communities from the looming climate crisis.
