Why Gardening Can Help with Depression and Allergies

A recent study suggests that soil, or rather the harmless bacteria Mycobacterium vaccae in it, could be as effective in changing your mood as antidepressant drugs.

The study was conducted with mice. Something that is often tested in people with depression is how much effort they will give something before they give up. The researchers used this logic when they placed mice in beakers filled with water to observe how long they would swim before giving up on finding an exit. Three groups of mice were placed in the beakers. One group was the control group and had not been exposed to Mycobacterium vaccae and were not given any antidepressants. However antidepressants were given to one of the groups of mice and the third group was exposed to Mycobacterium vaccae.

The controlled mice gave up on finding a exit much sooner than the other two groups, which had very similar results. The leader of the study, Chris Lowry of the University of Bristol in England, was reported as saying, "At the risk of anthropomorphizing, you could say the [Mycobacterium vaccae exposed] mice had a more active coping style."

A few years ago Mycobacterium vaccae was used on cancer patients. In the study two groups of patients, one group was exposed to Mycobacterium vaccae and the other wasn't, were interviewed about how they felt. Physically, neither group was getting better but the group that was exposed to Mycobacterium vaccae reported having a better quality of life.

"M. vaccae is no longer being pursued as a treatment for cancer, because it didn't prolong life, but patients did report increases in things like vitality and cognitive function and decreases in pain," Lowry said and mentioned that scientists still do not know how Mycobacterium vaccae improves a person's mood. "We don't know the mechanism. That's something that we would desperately like to know," said Lowry.

In addition to depression previous studies that have been done have linked exposure, especially during early childhood, to bacteria to the protection against both allergies and asthma. This suggests that bacteria-exposure will boosts someone's immune system and possibility alter the vulnerability that someone would have had to the conditions.

"These studies help us understand how the body communicates with the brain and why a healthy immune system is important for maintaining mental health," Lowry said and added. "They also leave us wondering if we shouldn't all be spending more time playing in the dirt."