Bacteria may help treat depression

An experimental cancer therapy may help point the way to a new treatment for clinical depression. The approach was inspired by work done by Dr. Mary O'Brien at the Royal Marsden Hospital in London, who injected lung cancer victims with Mycobacterium vaccae, a harmless version of bacteria that causes tuberculosis and leprosy. After the therapy was injected, the physician noted not only fewer symptoms of cancer, but an improvement in emotional health as well. Researchers followed that observation with an animal study to see if the bacteria would trigger an immune response that caused mice to produce additional amounts of serotonin, a neurotransmitter that is often in short supply among depressed patients. The positive response in mice, which responded with a stress-free attitude to swimming, is spurring a new look at a theory that ultra-hygienic environments for children may be contributing to higher rates of depression.

- read the report on the study from The Economist