A study by New England researchers looks at how weather and season influence brain size, comparing over three thousand MRI scans and finding small but distinct effects. “Basically, on a stormy day or in the winter, the cerebellum is larger than normal, while the rest of the brain is smaller than normal,” says researcher Gregory Book, of Olin Neuropsychiatry Research Centre. “In summer, the opposite happens.”
The cerebellum regulates voluntary movement as well as balance and co-ordination. Previously, changes in brain volume were assumed to be due to hydration, but the real cause may be air pressure.
Seasonal changes in brain volume are already well established in other animals. The common shrew’s brain shrinks significantly in winter, and it appears to lose some spatial skills. There may be an underlying evolutionary reason for the change.
Book says that the research, which is still at the pre-print stage and is undergoing review, could indicate previously unknown seasonal effects. “While the average effect observed is small, it may mean that some people are more susceptible to exacerbation of symptoms of certain disorders from weather or season,” says Book. Conditions such as arthritis, MS and migraine are known to flare up in winter and low pressure. Further studies on brain volume may help shed light on why this happens.
