Stress and the immune system: preliminary observations in rheumatoid arthritis using an in vivo marker of immune activity

Impact of Chronic Stress on Attention Control: Evidence from Behavioral and Event-Related Potential Analyses

Chronic stress affects brain function, so assessing its hazards is important for mental health. To overcome the limitations of behavioral data, we combined behavioral and event-related potentials (ERPs) in an attention network task. This task allowed us to differentiate between three specific aspects of attention: alerting, orienting, and execution. Forty-one participants under chronic stress and 31 non-stressed participants were enrolled. On the performance level, the chronically stressed group showed a significantly slower task response and lower accuracy. Concerning ERP measures, smaller cue-N1, cue-N2, and larger cue-P3 amplitudes were found in the stressed group, indicating that this group was less able to assign attention to effective information, i.e., they made inefficient use of cues and had difficulty in maintaining alerting. In addition, the stressed group showed larger target-N2 amplitudes, indicating that this group needed to allocate more cognitive resources to deal with the conflict targets task. Subgroup analysis revealed lower target-P3 amplitudes in the stressed than in the non-stressed group. Group differences associated with the attention networks were found at the ERP level. In the stressed group, excessive depletion of resources led to changes in attention control. In this study, we examined the effects of chronic stress on individual executive function from a neurological perspective. The results may benefit the development of interventions to improve executive function in chronically stressed individuals.

[Psychoneuroimmunology: an update]

Psychoneuroimmunology (PNI) is closely associated with the bidirectional pathways between mind/brain and the immune system. PNI research represents a rapidly growing area within psychosomatic research. Recent studies in PNI are based mainly on the immunological concepts of Th1/Th2 dichotomy and inflammation. This review covers human PNI studies dealing with stress-associated changes in cytokine (Th1, Th2) levels in immune-related processes such as wound healing, atopic diseases as well as autoimmune and other inflammatory diseases. It is shown that PNI studies measuring immune activity near the site of the disease (e. g. woundhealing) and dealing with objective stressors show more consistent findings (stress-associated Th1/Th2 shift, stress-associated proinflammatory activation) than those dealing with chronic and complex diseases (e. g., autoimmune disease). This warrants the expansion of the methodological repertoire in future PNI research toward designs allowing for the investigation of complex psychosomatic phenomena.

Models of adjustment to chronic illness: Using the example of rheumatoid arthritis

There are a number of theoretical frameworks that attempt to explain how individuals may adjust to threats to health and serious physical illness. The three major paradigms that attempt to organize key components of health and adaptation to illness include the following: the biomedical model which emphasizes disease; psychological models of adaptation to illness; and biopsychosocial models with the latter two emphasizing health, functioning, and well-being. Each of these three major paradigms, including biomedical, psychosocial, and biopsychosocial frameworks, is discussed and critiqued in turn, and contributions and theoretical issues in terms of adjustment to chronic illness, particularly rheumatoid arthritis (RA), are highlighted. Furthermore, a biopsychosocial framework for conceptualizing adjustment to physical illness is proposed that incorporates elements from key existing biomedical and psychosocial models of adaptation to chronic physical health issues.

Stress system response and rheumatoid arthritis: a multilevel approach

A growing body of research indicates that the stress system, and its interactions with the immune system, play a pivotal role in the aetiology and progression of rheumatoid arthritis (RA). The stress system has multiple levels and comprises physiological, psychological and environmental components. However, most investigations in RA that involve the stress system tend to focus on the interrelationships between neuroendocrine and immune function, and related disease activity, with little regard for the role of other aspects of stress system activation, including psychological variables. This is despite the fact that psychological stressors, and related psychological variables, are known to influence RA disease activity. This article aims to explore the multiple levels of stress system activation and how they may ultimately influence disease-related outcomes in RA. Some measurement issues of psychological stress will also be examined.

[Psychoimmunology: a questionable model?]

INTRODUCTION

The concept of "psychoimmunology" that had long been supported by clinical observation and common sense, has acquired a sound scientific basis in the last two decades. The discovery of neuro-mediators and cytokines and their receptors shared by the central nervous system and the immune system has prompted research work using reliable methodologies to study the relationship between a 'hard' scientific field, such as immunology, and a 'soft' one, such as the behavioral sciences.

CURRENT KNOWLEDGE AND KEY POINTS

The complexity of the studies on stress and immunity lies upon the choice of immunological measurements and the development of reproducible stress protocols. Models of stress in experimental animals may address acute versus chronic stress, and individual versus social stress. In humans, typical situations such as academic exams, and care given to patients with dementia, for instance, have been chosen to study large groups of subjects. The development of self-questionnaires for a reliable evaluation of stress and its consequences has led to more accurate measurements of psychosocial events. In animals, acute stress usually drives the immune response towards a Th2, grossly 'immunosuppressive,' profile. In humans, acute stress associates an endocrine response (characterized by glucocorticoid secretion and hyperprolectinemia) with an immunosuppression. Chronic stress is more likely to induce a range of effects, depending on the capacity of the subject to cope with stress, and on his/her social environment. Among the numerous mediators of the hypothalamo-pituitary cascade, Corticotropin Releasing Hormone is a key factor in the stress-immunity relationship. Several studies in humans have demonstrated the influence of stress on the susceptibility to infections (including HIV infection) and on survival in malignant diseases. In autoimmune diseases, a high prevalence of depression, as well as a particular sensitivity to stressful events, seem to modify the course of conditions such as systemic lupus erythematosus, rhumatoid arthritis or Sjögren's disease. The relationship between stress and diseases is based on the pathogenic model which involves the following chain of events: stressor, reaction to stress, neuro-endocrine changes, abnormalities of the immune response, and occurrence (or aggravation) of a disease. The evolution from health to disease could be associated, at least partially, with a 'passive' immunosuppressive mode of response, mediated by the pituitary-adrenal axis, typically the opposite of an 'active,' immunostimulant mode of response, mediated by adrenergic stimulation.

FUTURE PROSPECTS AND PROJECTS

Concept-related problems still remain to be solved: adaptation to stress ('coping'), is both genetically and socially mediated; the significance and interpretation of stress-related abnormalities and their precise involvement in the pathogenesis of diseases may be ambiguous. However, available epidemiological and pathophysiological evidence is currently sufficient to allow physicians in their everyday practice to take stress and depression into account in order to markedly improve the prognosis of many diseases related to immune responses. Prospective studies of neuropsychological intervention, using either pharmacologic or behavioral approaches, should be made to provide the necessary rational to a psychoimmunological management of patients.