Psychoneuroimmunology Shifts Away from Stress-Based Models: Field on the Move

Article excerpt

ASPEN, COLO. -- Psychoneuroimmunology has changed drastically since many physicians first encountered the field in medical school, Mark L. Laudenslager, Ph.D., said at a meeting on stress sponsored by the University of Colorado.

The dominant theme in psychoneuroimmunology in the 1970s and 1980s was that stress suppresses the immune response. True as far as it goes--but almost laughably simplistic, compared with current understanding, according to Dr. Laudenslager of the university.

It's now clear that the brain, immune system, and endocrine system form a tripartite network in which bidirectional communication between each of the three pillars is the norm.

In other words, while it's certainly true that grief or depression is immunosuppressive, as was first recognized several decades ago, it's also the case that immunologic changes in the periphery--such as an increase in proinflammatory cytokines--get communicated to the brain with resultant effects upon behavior, mood, and cognition, he continued.

Moreover, stress is not always immunosuppressive. In Dr. Laudenslager's monkey studies, an acute stressor resulted in activation of natural cytotoxicity, as reflected by increased natural killer cell activity.

This alteration in host defenses may persist for many years after a major trauma. Dr. Laudenslager has shown that Vietnam combat veterans with posttraumatic stress disorder (PTSD) of several decades' duration had significantly greater natural killer cell activity than a control group of Vietnam combat veterans with a long-term history of alcohol abuse, but not PTSD. Depression comorbid with PTSD was associated with increased natural cytotoxicity, unlike the case in previous studies of depressed populations without PTSD.

Much of the work in psychoneuroimmunology of late has moved away from stress--based models altogether. The focus has shifted in pursuit of increased understanding of the routes of bidirectional communication between the brain, immune system, and endocrine system. …