Dr. Charles Raison, an associate professor of psychiatry in the University of Arizona College of Medicine and the College of Agriculture and Life Sciences at the University of Arizona said the physical benefits of gardening have been known for decades. People who live near green spaces and who have access to natural environments live longer than people who don't.
"There are now a number of studies to suggest gardening might beneficially impact a range of conditions: obesity, dementia, schizophrenia, depression," Raison statement.
Scientists found contact with Mycobacterium vaccae, a bacterium that lives in soil, can improve cognitive function and mood, Raison said.
"What's remarkable is that this micro-organism seems to know how exactly to signal the brain areas we believe are most important for reducing depressive symptoms," Raison said. "It's like it immediately goes on a mainline right up to this one particular area of the brain."
So far, most studies of M. vaccae have been done in animals, but Raison said he was hopeful future studies in humans could yield a new tool for fighting depression and other mood disorders.
Environmental psychologist Roger Ulrich found in 1984 hospital patients who had a view of trees and other green spaces outside their windows healed more quickly and with fewer complications than patients who faced a brick wall. Ulrich's finding was published in Science.