Psychosocial influences on immunity, including effects on immune maturation and senescence

Abstract

Studies investigating the influence of psychosocial factors on immunity played a critical and formative role in the field of psychoneuroimmunology (PNI), and have been a major component of articles published in Brain, Behavior and Immunity (BBI). An analysis of papers during the first two decades of BBI from 1987-2006 revealed three behavior-related topics were most prominent: (1) stress-induced changes in immune responses, (2) immune correlates of psychopathology and personality, and (3) behavioral conditioning of immunity. Important subthemes included the effect of early rearing conditions on immune maturation in the developing infant and, subsequently, psychosocial influences affecting the decline of immunity in the senescent host. The responsiveness of cell functioning in the young and elderly helped to validate the view that our immune competence is malleable. Many technical advances in immune methods were also evident. Initially, there was a greater reliance on in vitro proliferative and cytolytic assays, while later studies were more likely to use cell subset enumerations, cytokine quantification, and indices of latent virus reactivation. The reach of PNI extended from the traditional clinical entities of infection, autoimmunity, and cancer to attain a broader relevance to inflammatory physiology, and thus to asthma, cardiovascular and gastrointestinal disease. There continue to be many theoretical and applied ramifications of these seminal findings. Fortunately, the initial controversies about whether psychological processes could really impinge upon and modify immune responses have now receded into the pages of history under the weight of the empirical evidence.

Figure 1

An early perspective on PNI as envisioned by Cunningham (1981). Artistic rendition of his description of multiple levels of influence on the immune system, first within the body from the brain and other physiological systems. Simultaneously, extrinsic factors impinge upon by the individual, both from the social realm and physical world.

Figure 2

Historical summary of BBI articles published between 1987–2006, highlighting the number pertaining to psychological influences on immunity. Categorization was based on the main point emphasized in the title. Stress studies rivaled the proportion in the neurosciences (24%), and on hormone-immune interactions (14%) and general immunology (20%). Special issues with a focus on P-related topics were not included; they are designated with an asterisk (*) in the year they were published.

Figure 3

Illustration of the many types of psychological and behavioral factors that can affect immune competence. Developing and older individuals may be especially susceptible to psychosocial influences because the age-related changes of immune maturation and senescence increase responsiveness and extend the duration of immune effects.