Long-term stress suppresses immune system, particularly in those who are sick, finds meta-analysis

Michael Carter
Published: 09 July 2004

Long-term stress suppresses the ability of the immune system to fight viral as well as bacterial and parasitic infections, according to a meta-analysis of almost 300 studies published in the July edition of the Pyschological Bulletin. The investigators also found that the immune systems of individuals who are older or already suppressed due to illness are more prone to stress-related change.

Investigators analysed data from 296 studies conducted between 1969 and 2001 looking at the effects of stress on the immune system.

They identified different categories of stress ranging from short-term acute stress provoking a “fight or flight” reaction to chronic stress without any clear endpoint.

Different immune responses were also identified by the investigators. These included natural immunity, producing a fast-acting, all purpose response able to attack a variety of pathogens, and specific immunity. Specific immunity involves both a cellular response to fight viruses and other pathogens which invade the cells of the body, and humoral responses to fight bacteria and parasites.

The investigators correlated how natural immunity, and cellular and humoral responses were affected by stress.

They established that short-term stress which provoked a fight-or-flight response actually boosted natural immunity as the body primed itself to respond to challenges to the integrity of the skin and blood. However, the body’s short boost in natural immunity is achieved at the expense of specific immunity, which is suppressed.

Chronic stress was found by the investigators to be associated with global suppression of the immune system, resulting in a drop in immune function across the board. Duration of stress was also found to be significant with the beneficial effects of short-term stress on natural immunity turning into long-term suppression of both cellular and humoral specific immune functions.

Age and disease status were also found to affect an individual’s vulnerability to stress-related decreases in immune function.

Reference

Segerstrom SC et al. Pstychological stress and the human immune system: a meta-analytic study of 30 years of inquiry. Psychological Bulletin 130: 601-630, 2004.