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Tuesday, July 9, 2024 | Back issues
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Temperature extremes likely to affect brain development in children, study finds

Using MRI scans and statistics, European researchers discovered that the development of white matter lags in the brains of children and fetuses frequently exposed to the lower and upper end of temperature distribution.

(CN) — Early exposure to extreme temperatures may inhibit brain development in infants and toddlers, according to a study published Wednesday in the journal Nature Climate Change. Previous studies had already established that the developing brains of fetuses and children are vulnerable to environmental exposure, but researchers were uncertain about precise physiological changes. 

That mystery prompted scientists from the Barcelona Institute for Global Health (ISGlobal), the Erasmus University Medical Center Rotterdam (ERASMUS MC) and the Centro de Investigación Biomédica en Red (CIBER) to undertake a multiyear study of 2,681 children in the Netherlands, who were subjected to magnetic resonance imaging (MRI) between the ages of 9 and 12. 

The MRIs allowed researchers to study white matter in the brains of those subjects, where they could evaluate connectivity by measuring the volume and direction of water diffusion. Using statistics, the researchers estimated the exposure of each test participant to determine two parameters: mean diffusivity and fractional anisotropy. 

In developed brains, most water flows in one direction. Whereas in developing brains, it tends to flow in all directions. Developed brains will therefore give lower values for mean diffusivity and higher values for fractional anisotropy. 

"The fibers of the white matter are responsible for connecting the different areas of the brain, enabling communication between them,” explained Laura Granés, IDIBELL and ISGlobal researcher and first author of the study. “As the white matter develops, this communication becomes faster and more efficient. 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."

Granés said that in previous studies, the alteration of this parameter has been associated with poorer cognitive function and certain mental health problems.

The results indicate that exposure to extreme cold during pregnancy and infancy, and exposure to extreme heat from birth until 3 years of age “were associated with higher mean diffusivity at preadolescence, pointing to slower white matter maturation,” according to the report.

“The largest changes in connectivity parameters are observed in the first years of life,” said Carles Soriano, co-author and IDIBELL, UB and CIBERSAM researcher. “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.”

The trend was even more pronounced when isolating those on the lower end of the socioeconomic scale, as poorer children beset by substandard housing conditions and high energy costs tend to be more vulnerable to extreme weather.

Probable effects of extreme temperatures on neurodevelopment include a loss of sleep quality, a disruption of placental functions, activation of the hormonal axis leading to higher cortisol production, and inflammatory processes.

“Our findings help to raise awareness of the vulnerability of fetuses and children to changing temperatures,” said Mònica Guxens, researcher at ISGlobal, Erasmus MC and CIBERESP, adding the findings “also stress the need of designing public health strategies to protect the most vulnerable communities in the face of the looming climate emergency.”

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Categories / Health, Science

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