PET shows link between endorphins, depression

Researchers have found more evidence that depression has its roots in specific alterations within the brain, particularly in the endorphin system that is a central part of the brain's natural pain and stress reduction capability.

Susan Kennedy, Ph.D., and colleagues at the University of Michigan Molecular and Behavioral Neuroscience Institute evaluated 28 women, 14 with major depression, and 14 healthy controls. Subjects were asked to recall a sad life event while undergoing PET with radiolabeled carfentanil. Nondepressed women did not activate their micro-opioid system. Depressed women's micro-opioid system, however, was overactive even at baseline (Arch Gen Psych 2006:63;1199-1206).

This is the first time that specific differences in the micro-opioid system have been shown between people with depression and those without, according to the study.