The regions of the brain associated with olfaction are more developed in professional perfumers than in the general population. In addition, the quantity of grey matter in the experts' olfactory regions increases in proportion to their experience. [...] Based on anatomical MRI scans of professional perfumers, perfumery students and control subjects, it shows that training and practice make it possible to reverse the age-related grey matter reduction observed in olfactory regions among the general population.

— For the rest of us, these regions of the brain tend to shrink with age. Read more at Experience modifies the perfumer's brain at CNRS. They scanned the brains of perfumer Jean-Claude Ellena and students at the ISIPCA perfumery school, among others.