New Delhi: Exposure to high temperatures during pregnancy and early infancy could be associated with a slower growth of the thalamus, brain’s information processing centre, later in childhood, a study has found.
Climate change is increasing exposure to extreme temperatures worldwide, raising concerns about its impact on children’s health.
Findings published in the journal Environment International suggest that heat exposure during one’s earliest stages of life may have lasting effects on brain development.
Researchers, led by those at the Barcelona Institute for Global Health (ISGlobal) in Spain, said that while previous studies have linked heat exposure to changes in cognition and mental health, there is not much literature about effects on brain structure.
A slower thalamic growth was also associated with behavioural symptoms during adolescence, including aggression and rule-breaking. However, an association with cognitive performance was not found.
“With global temperatures continuing to rise, measures to reduce heat exposure during pregnancy and early infancy could play an important role in protecting children’s brain development,” author Monica Guxens, a research professor at the Barcelona Institute for Global Health and coordinator of the study, said.
The study included 3,251 children participating in the Generation R Study, a birth cohort in the Netherlands.
“We used a high-resolution climate model that provided weekly outdoor temperature estimates during pregnancy and monthly estimates from birth to 8.5 years of age at each participant’s place of residence. We then analysed brain MRI scans performed at around 10 and 14 years of age,” first author Laura Granes, an ISGlobal researcher, said.
Changes to volume of 11 brain structures over time were analysed, along with whether the changes were linked with an earlier exposure to heat or cold.
Among the brain regions studied, only the thalamus showed a consistent association with early-life heat exposure, the researchers said.
The brain region, which acts as the main relay centre, processing and transmitting sensory and motor information to the cerebral cortex, may be particularly sensitive because it develops very early in pregnancy and follows a tightly regulated developmental timeline, they said.
Rich blood supply to the thalamus during foetal development may also make it more vulnerable to heat-related changes affecting the placenta or blood flow to the foetus, the team added.
A clear period of vulnerability was identified, spanning pregnancy and the first months after birth.
Compared with a reference average temperature of 12.5 degrees Celsius, exposure to monthly mean temperatures of 20.5 degrees Celsius during the period — calculated across day and night — was associated with a slower thalamic growth between nine and 15 years of age.
No similar associations were found for other brain structures or for exposure to cold temperatures.
