Worried sick: hassles and herpes.

Worried sick: Hassles and herpes

A growing number of studies are finding links between psychological states--particularly stress--and immune function. The emerging facts have given birth to a new discipline, psychoneuroimmunology, which seeks to understand the links between psychological status, central nervous system activity, endocrine function and immune response.

In trying to understand this complex relationship, neurobiologists and physicians have found it useful to study people with herpesvirus infections. The virus spends most of its time in a latent, or inactive, phase, residing in the cell bodies of certain peripheral nerves. Occasionally it becomes active, reproduces and is transported down the nerve-cell axons to the skin, where it may cause the formation of blisters or "cold sores.' Anecdotal evidence has linked herpes reactivation to psychological stress, but only recently have controlled studies confirmed that link.

New research by Susan Kennedy and her colleagues at Ohio State University's College of Medicine in Columbus took psychological and immunological data from married men and compared them to separated or divorced men matched for age and education; all the subjects had herpes. Separated and divorced men were more anxious, depressed and lonely than their married counterparts--and had higher levels of herpesvirus antibodies. Since antibody levels go up during periods of viral reactivation, higher antibody levels are believed to reflect a depressed immune system incapable of keeping the viral infection under control.

Among married men, marital quality had its correlates with immune function as well. Poorer marital quality was related to higher viral antibody levels, and lower ratios of helper T cells to suppressor cells--another measure of immune suppression.

Other researchers are finding that immune function may be linked not only to personal stress, but also to the perception that others nearby are experiencing stress. Jill Irwin at Queen's University in Kingston, Canada, and her colleagues at the University of Rochester (N.Y.) measured the activity of natural killer cells in mice exposed to foot shocks, and compared those measures to unstressed mice. Unstressed mice not in the vicinity of the stressed mice showed no suppression of normal immunity as measured by killer cell activity. But unstressed mice kept in cages close enough to hear and smell their stressed neighbors showed significant drops in killer cell activity.

The researchers suggest that cues associated with a nearby stressful experience may provoke changes in immune function, perhaps as a result of an increase in sympathetic nervous activity. Such activity--the so-called fight or flight response-- has been shown to suppress immunity.