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New research by the Barcelona Institute for Global Health (ISGlobal) revealed that exposure to heat and cold during pregnancy and early childhood can have enduring effects on the microstructure of white matter in the brains of preadolescents, particularly in socioeconomically disadvantaged communities.

Led by researchers from ISGlobal, in collaboration with Erasmus University Medical Center Rotterdam and the Centro de Investigación Biomédica en Red (CIBER), the study showed the vulnerability of foetuses and children to extreme temperatures and the potential long-term impact on brain development.

Dr. Mònica Guxens, lead researcher and ISGlobal, Erasmus MC, and CIBERESP scientist, noted the susceptibility of developing brains to environmental exposures and emphasizes the lack of previous studies assessing structural brain changes due to temperature fluctuations.

"We know that the developing brain of foetuses and children is particularly susceptible to environmental exposures, and there is some preliminary evidence suggesting that exposure to cold and heat may affect mental well-being and cognitive performance in children and adolescents," Guxens said, Neuroscience News reported.

"However, there is a lack of studies evaluating potential changes in brain structure as a result of these exposures," she added.

In this investigation, a group headed by Guxens examined the white matter composition in the brains of preadolescents to pinpoint periods of vulnerability to cold and heat exposure during early life.

The study published in Nature Climate Change, encompassed 2,681 children from the Generation R Study, a birth cohort based in Rotterdam, who underwent magnetic resonance imaging (MRI) between the ages of 9 and 12.

The MRI protocol examined brain connectivity by gauging the magnitude and direction of water diffusion within the brain's white matter. In brains that are more developed, water tends to flow predominantly in one direction rather than in all directions, resulting in decreased values for a metric known as mean diffusivity and increased values for another metric termed fractional anisotropy.

The research team employed a sophisticated statistical method to gauge, for every participant, the exposure to monthly average temperatures from conception until the age of 8, and their impact on the MRI connectivity parameters (mean diffusivity and fractional anisotropy) measured between 9 and 12 years of age.

Laura Granés, IDIBELL and ISGlobal researcher and study co-author, explained that altered white matter maturation, indicated by higher mean diffusivity, has been linked to cognitive deficits and mental health issues in previous studies.

"The fibres of the white matter are responsible for connecting the different areas of the brain, enabling communication between them. As the white matter develops, this communication becomes faster and more efficient," Granés said.

"Our study is like a photograph at a particular moment in time and what we see in that image is that participants more exposed to cold and heat show differences in a parameter - the mean diffusivity - which is related to a lower level of maturation of the white matter."

"The largest changes in connectivity parameters are observed in the first years of life," stated co-author Carles Soriano, a researcher from IDIBELL, UB, and CIBERSAM. "Our results suggest that it is during this period of rapid brain development that exposure to cold and heat can have lasting effects on the microstructure of white matter."

Furthermore, the study highlighted the socioeconomic disparities in vulnerability to temperature exposure, with children from poorer neighborhoods showing heightened susceptibility to temperature-related impacts on brain development, possibly due to housing conditions and energy poverty.

Dr. Guxens stressed the importance of public health strategies to protect vulnerable communities in the face of climate change, recognizing the urgent need to address the potential consequences of temperature variations on neurodevelopment in early life.