Dirt Is Cheaper Than Prozac: Mood-Boosting Bacteria?

I've heard about exposure to dirt strengthening the immune system -- but could it make you feel better, too?

Treatment of mice with a ‘friendly’ bacteria, normally found in thesoil, altered their behavior in a way similar to that produced byantidepressant drugs, reports research published in the latest issue ofNeuroscience. [...]

Interest in the project arose after human cancer patients beingtreated with the bacteria Mycobacterium vaccae unexpectedly reportedincreases in their quality of life. Lowry and his colleagues reasonedthat this effect could be caused by activation of neurons in the brainthat contained serotonin.

When the team looked closely at thebrains of mice, they found that treatment with M. vaccae activated agroup of neurons that produce the brain chemical serotonin. The lack ofserotonin in the brain is thought to cause depression in people, thusM. vaccae’s effects on the behavior of mice may be due to increasingthe release of serotonin in parts of the brain that regulate mood.

The usual caveats are doubled here: it's a mouse study of anotoriously difficult-to-measure characteristic. But the principle isinteresting ... what if the rise in childhood behavioral disorders was related tothe shift from playing outdoors to playing inside?

Spring is here. Let's get dirty!
Getting dirty may lift your mood [press release]