How the seasons might influence brain size

Research suggests that changes in air pressure can cause changes in brain volume, in humans as well as in animals

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.