Heat exposure in early life may impair brain development, study finds

New research suggests that high temperatures during critical developmental periods in early life could have lasting effects on brain structure. A study published in "Environment International" by the Barcelona Institute for Global Health (ISGlobal) investigated the link between temperature exposure from conception to 8.5 years old and brain development in later childhood and adolescence.

Scientists analyzed MRI scans of 3,251 children born in the Netherlands between 2002 and 2006. Using a high-resolution climate model, they estimated weekly outdoor temperatures during pregnancy and monthly temperatures from birth up to age 8.5 for each participant. The study measured changes in the volume of 11 brain structures over time, specifically looking for correlations with prior heat or cold exposure.

The findings indicated that only the thalamus, the brain's primary relay center for sensory and motor information, showed a consistent association with early-life heat exposure. Researchers hypothesize that the thalamus's rapid development early in pregnancy and its well-vascularized nature make it particularly susceptible to external conditions. Changes affecting the placenta or fetal blood flow due to heat could impact this structure.

Researchers identified a critical window of vulnerability for the thalamus to heat exposure occurring during pregnancy and the first five months of life. Higher temperatures during this period were associated with slower growth of the thalamus between ages 9 and 15. Notably, similar associations were not found for other brain structures or in relation to cold temperature exposure, underscoring the specific impact of heat during these sensitive early stages.

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We wanted to examine whether exposure to high or low temperatures from conception to 8.5 years of age is associated with changes in brain development in late childhood and adolescence, and to identify the periods in which the brain is most susceptible to these changes.