Summary: Early exposure to extreme temperatures can impact the development of the brain’s white matter, particularly in children from poorer neighborhoods. Researchers found that cold during pregnancy and heat during infancy slowed white matter maturation in preteens.
This highlights the vulnerability of developing brains to environmental factors and the need for protective public health strategies. The findings highlight the importance of addressing climate impacts on children’s health.
Highlights:
- Early exposure to extreme temperatures affects white matter development.
- Children from poorer neighborhoods are more vulnerable to these effects.
- The study used MRI to analyze brain connectivity in 2,681 preteens.
Source: ESTGLOBAL
Brain scans taken on more than 2,000 preteens suggest that early exposure to heat and cold could have lasting effects on the brain’s white matter microstructure, particularly when they live in poorer neighborhoods.
The study, published in Natural climate change, highlights the vulnerability of fetuses and children to extreme temperatures.
This research was led by the Barcelona Institute for Global Health (ISGlobal), a center supported by the “la Caixa” Foundation, and IDIBELL, in collaboration with the Erasmus University Medical Center Rotterdam (ERASMUS MC) and the Centro of Biomedical Investigation in Red (CIBER): areas of Public Health Epidemiology (CIBERESP) and Mental Health (CIBERSAM).
In the current context of climate emergency, the impact of extreme temperatures on human health constitutes a major concern for the scientific community and society. Children are particularly vulnerable to temperature changes because their thermoregulatory mechanisms are still immature.
“We know that the developing brains of fetuses and children are particularly sensitive to environmental exposures, and some preliminary evidence suggests that exposure to cold and heat may affect the mental well-being and cognitive performance of children and adults. adolescents”, explains Mònica Guxens, researcher at ISGlobal, Erasmus MC and CIBERESP.
“However, there is a lack of studies assessing potential changes in brain structure resulting from these exposures,” she adds.
In this study, a team led by Guxens examined white matter structure in preadolescent brains to identify windows of susceptibility to cold and heat exposure early in life.
The analysis included 2,681 children from the Generation R study, a birth cohort in Rotterdam, who underwent magnetic resonance imaging (MRI) between ages 9 and 12.
The MRI protocol assessed brain connectivity by measuring the magnitude and direction of water diffusion in the white matter of the brain. In more mature brains, water flows more in one direction than in all directions, resulting in lower values for a marker called mean diffusivity and higher values for another marker called fractional anisotropy.
The research team used an advanced statistical approach to estimate, for each participant, exposure to monthly average temperatures from conception to age 8, and their effect on these MRI connectivity parameters (mean diffusivity and fractional anisotropy) measured between 9 and 12 years of age.
Susceptibility window between pregnancy and age three
The results show that exposure to cold during pregnancy and the first year of life, as well as exposure to heat from birth to age 3, were associated with higher mean diffusivity at preadolescence, indicating slower maturation of white matter.
In this case, “cold” and “heat” are defined as temperatures that lie at the lower and upper ends of the temperature distribution in the region studied, respectively.
“The white matter fibers are responsible for connecting the different areas of the brain, thus allowing communication between them. As white matter develops, this communication becomes faster and more efficient.
“Our study is like a snapshot of a single point in time and what we see in this image is that participants most exposed to cold and heat show differences in a parameter – mean diffusivity – which is linked to a lower level of white matter maturation,” explains Laura Granés, IDIBELL and ISGlobal researcher and first author of the study.
“In previous studies, impairment of this parameter has been associated with poorer cognitive function and some mental health problems,” she adds.
“The most important changes in connectivity parameters are observed during the first years of life,” explains Carles Soriano, co-author and researcher at IDIBELL, UB and CIBERSAM. “Our results suggest that it is during this period of rapid brain development that exposure to cold and heat may have lasting effects on white matter microstructure.”
No association was found between temperature exposure early in life and fractional anisotropy between 9 and 12 years of age. The authors argue that a possible explanation is that these two measurements reflect different microstructural changes and that mean diffusivity might be a more robust indicator of white matter maturation, compared to fractional anisotropy.
The poorest children are more at risk
An analysis stratified by socioeconomic conditions showed that children living in poorer neighborhoods were more vulnerable to exposure to cold and heat. In these children, the windows of sensitivity to cold and heat were similar to those identified in the overall cohort, but started earlier. These differences may be linked to housing conditions and fuel poverty.
An important mechanism this could explain that the effect of ambient temperature on neurological development could be linked to poorer sleep quality. Other possible mechanisms include disruption of placental functions, activation of the hormonal axis leading to higher cortisol production, or inflammatory processes.
“Our results help raise awareness of the vulnerability of fetuses and children to temperature changes,” says Guxens. The findings also highlight the need to design public health strategies to protect the most vulnerable communities in the face of the looming climate emergency.
About this neurodevelopment research news
Author: Paul Rubio
Source: ESTGLOBAL
Contact: Pau Rubio – ISGLOBAL
Picture: Image is credited to Neuroscience News
Original research: Closed access.
“Early life exposure to cold and heat and white matter microstructure in preadolescents” by Mònica Guxens et al. Climate change
Abstract
Early life cold and heat exposure and white matter microstructure in preadolescents
Prenatal life and childhood represent periods vulnerable to environmental exposures. Cold and heat may have negative effects on children’s mental health and cognition, but the underlying neural mechanisms are unknown.
Here, through magnetic resonance imaging assessment of 2,681 children from the Dutch Generation R birth cohort, we show that heat exposure during infancy and early childhood as well as cold exposure during pregnancy and early childhood are associated with higher mean diffusivity in preadolescence, indicating reduced myelination. and maturation of white matter microstructure.
No association for fractional anisotropy was observed. Children living in poorer neighborhoods were more vulnerable to exposure to cold and heat.
Our results suggest that exposure to cold and heat during periods of rapid brain development could have lasting effects on children’s white matter microstructure, a risk that needs to be considered in the context of climate change in course.