A therapy used to treat Parkinson's disease may help patients who suffer from the most severe forms of depression, researchers say. The treatment, called deep brain stimulation (DBS), is a minimally invasive surgery in which doctors place electrodes into specific parts of the brain that are believed to be malfunctioning. Once in place, the electrodes emit tiny, adjustable, electrical pulses that block dysfunctional activity in the brain. In clinical studies, researchers found that DBS cut...