Stress Consequences

Mental, Neuropsychological and Socioeconomic

George Fink, George Fink

• Verlag: Academic Press
• Jahr: 2010
• ISBN:
  9780123751751
• Thema: Psychology
• Thema: Clinical Psychology

Stress is a universal phenomenon that impacts adversely on most people. This volume provides a readily accessible compendium that focuses on the physical and psychological consequences of stress for individuals and society. Clinical attention focuses on disorders of the stress control system (e.g. Cushing's Syndrome: Addison's Disease) and the adverse impact of stress on human physical and mental health. Detailed reviews address disorders such as PTSD, anxiety, major depression, psychoses and related disorders such as combat fatigue and burnout. The work covers interactions between stress and neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease, as well as stress-immune-inflammatory interactions in relation to cancer and autoimmune and viral diseases. Emphasis is also placed on the role of stress in obesity, hypertension, diabetes type II and other features of the metabolic syndrome which has now reached epidemic proportions in the USA and other countries.

• Chapters offer impressive scope with topics addressing animal studies, disaster, diurnal rhythms, drug effects and treatments, cognition and emotion, physical illness, psychopathology, immunology and inflammation, lab studies and tests, and psychological / biochemical / genetic aspects
• Richly illustrated in full color with over 200 figures
• Articles carefully selected by one of the world's most preeminent stress researchers and contributors represent the most outstanding scholarship in the field, with each chapter providing fully vetted and reliable expert knowledge

III

Mental Disorders

A

Personality and Personality Disorders

Stress of Self Esteem

J.C. Pruessner

S. Wuethrich

M.W. Baldwin McGill University, Montreal, Quebec, Canada

Glossary

Cortisol A steroid hormone secreted by the human adrenal glands. It is often released in high amounts during periods of stress. High doses lead to interference with the proper functioning of the immune system.

Hippocampus Seahorse-shaped structure that extends along the inferior horn of each lateral ventricle of the brain and consists of gray matter covered on the ventricular surface with white matter. A part of the limbic system, it is involved in the storage of memory for intermediate periods and the consolidation of those memories into permanent form.

Hypothalamic-pituitary-adrenal (HPA) axis The major part of the neuroendocrine system that controls reactions to stress and has important functions in regulating various body processes such as digestion, the immune system, and energy usage. Most species (from humans to simple organisms) share components of the HPA axis. It regulates a set of interactions among glands, hormones, and parts of the midbrain that mediate the general adaptation syndrome proposed by Selye.

Locus of control The perception of factors responsible for the outcome of an event. An individual with high internal locus of control believes that his or her own actions caused the outcome. Conversely, an individual with high external locus of control believes the outcome was determined by outside forces.

Personality The complex of all attributes – behavioral, temperamental, emotional, and mental – that characterize an individual.

Self-esteem Stressor The global value we place on ourselves. Any emotional or physical demand (positive or negative) that gives or results in stress.

The Role of Personality in the Perception of Stress

Lazarus, who has devoted much of his work to the study of stress, noted early on that stressful conditions per se fail to produce reliable effects on task performance. Keeping all situational variables constant, the same stressor can have minimal effect, lead to performance improvement, or result in significant performance impairment across subjects. This led him and others to suggest that individual differences in motivational and cognitive variables are likely to interact with situational components, and what is considered threatening for some, and thus stressful and performance impairing, might be considered as stimulating by others, and thus produce beneficial effects on performance.

Subsequent research identified the process of evaluation as crucial in explaining the impact of psychological variables on the stress response. Any internal or external stimulus is perceived as stressful only if it is evaluated as harmful or threatening. The early notion of the importance of the evaluation has received recent validation with the identification of social evaluative threat as the single most important factor in determining the stressfulness of a situation in laboratory stress studies.

The Importance of Self-esteem and Locus of Control in the Perception of Stress

A case can be made that the personality variables self-esteem and locus of control play a central role in the evaluation of many situations and thus contribute to the experience of stress. Self-esteem is broadly defined as the value we place on ourselves. Epidemiological studies have shown that low self-esteem is associated with negative life outcomes, including substance abuse, delinquency, unhappiness, depression, and worsened recovery after illnesses. On the other hand, high self-esteem has been linked to happiness and longevity. In studies of aging, a positive self-concept has been identified to play a key role in successful aging, predicting independence, cognitive stability, and general health in old age.

Internal locus of control can be defined as the perception that one’s outcomes are determined by one’s actions. Not surprisingly, internal locus of control and self-esteem are usually highly correlated. The key link of these variables to the experience of stress lies in their impact on the evaluation of any given situation. We postulate that in the evaluation of whether a given situation is threatening or benign, self-esteem and internal locus of control systematically interact with situational factors. If a person attributes little importance to him- or herself and thinks that he or she has little impact on the outcome of his or her own actions, this person will find more situations uncontrollable and unpredictable, and consequently will evaluate more situations as threatening and harmful.

Endocrinological Evidence for the Role of Self-esteem and Locus of Control in the Perception of Stress

Evidence for the impact of self-esteem and locus of control on stress perception emerged when subjects were exposed to repeated psychological stress, using the Trier Psychosocial Stress Test (TSST). In this paradigm, subjects have to give an impromptu speech and perform serial subtraction tasks in front of an audience, usually for about 10 min. The audience consists of two to three persons who are instructed to maintain a neutral expression, being neither explicitly rejecting nor confirmative in their facial expression or gestures. During the speech, the audience interacts with the subject only to indicate the amount of time that is left to talk or to ask specific questions. In the case that a subject stumbles, they encourage the subject to continue the speech. During the serial subtraction task, the subject is interrupted only when making a mistake. The subject is then corrected and instructed to start the task over. The task was designed to represent a significant social-evaluative threat and indeed has been shown to be a powerful stressor, stimulating the hypothalamic-pituitary-adrenal (HPA) axis and leading to significant free cortisol increases within 15 to 30 min following the onset of the task. This first study aimed to validate the long-standing hypothesis that in humans, repeated exposure to the same stressor would lead to quick habituation of the stress response. In order to test the habituation of the stress response, 20 young healthy male college students were exposed to the TSST on five subsequent days. For this purpose, the TSST was modified using different speech topics and serial subtraction tasks on each day. Interestingly, only 13 of the 20 subjects showed the typical habituation pattern, with a normal stress response on day one being significantly reduced on day two, and no longer present on the subsequent days. In the seven remaining subjects, however, the cortisol stress response continued to be present on all days and only showed a tendency to decline toward the end of the testing (Figure 1). When analyzing the available psychological variables, it became apparent that low internal locus of control and low self-esteem were the best predictors of failing habituation of the cortisol stress response to repeated stress exposure. This can be interpreted as a sign that these personality variables interact with the evaluation of a situation during repeated exposure. The absence of differences in the stress response between the two groups of subjects on day one was at the time attributed to the effect of novelty – the novelty of the situation might have made it unpredictable and uncontrollable for everybody on the first exposure and might thus have masked the impact of personality variables on stress perception and response. One conclusion at the time was that in order to reveal the effect of personality variables on the stress evaluation and response, one would likely need repeated exposures to the same stressor in order to reveal the influence of personality variables on stress.

Figure 1 Cortisol responses (AUC, area under the curve) on repeated exposure to the Trier Social Stress Test (TSST) on 5 subsequent days in subjects with high self-esteem and high locus of control (high SEC; n = 13) and low self-esteem and low locus of control (low SEC; n = 7).

However, it is known that personality variables tend to have relatively weaker effects when situational factors are very strong. In a second study, the threatening aspects of the situation were reduced, and self-esteem and locus of control had an impact on the perception of stress on the first exposure to a stimulus. Here, computerized mental arithmetic was combined with an induced failure design to invoke stress. In the setup used in this task, 52 students performed the task on computer terminals in front of them. Half of the students were exposed to a difficult version leading to low performance, compared to an easy version of the task with high performance for the other half. The students played the task in three 3-min segments and had to announce their performance score after each segment to the investigator, who wrote the scores down on a board for everybody to see. Saliva sampling before, throughout, and after the task allowed the assessment of the cortisol dynamics in relation to this paradigm. Interestingly, this task triggered a significant cortisol release only in the subjects who were in the low-performance group and had low self-esteem and low internal locus of control. Neither low performance alone nor low self-esteem and internal locus of control alone were significant predictors of cortisol release, supporting the notion that these personality variables produce effects only in interaction with a potentially stressful situation (Figure 2). The evaluation of the situation is suggested to be at the core of this interaction.

Figure 2 Cortisol stress responses to the Trier Mental Challenge Task (TMCT) in four groups of subjects, separated for high and low self-esteem and locus of control and high and low performance in the mental arithmetic. The performance was manipulated by the investigator.

The Hippocampus as a Possible Mediator of the Relationship between Self-esteem, Locus of Control, and Stress

Although studies on brain correlates of personality variables and endocrine function in humans are only starting to appear, a picture is emerging that puts the spotlight on the hippocampus as a likely mediator between the previously reported personality variations and stress responses. The hippocampus is one of the major limbic system structures involved in the regulation of the stress response, and variations in hippocampal volume (HCV...