The present report meta-analyzes more than 300 empirical articles describing a relationship between psychological stress and parameters of the immune system in human participants. Acute stressors (lasting minutes) were associated with potentially adaptive upregulation of some parameters of natural immunity and downregulation of some functions of specific immunity. Brief naturalistic stressors (such as exams) tended to suppress cellular immunity while preserving humoral immunity. Chronic stressors were associated with suppression of both cellular and humoral measures. Effects of event sequences varied according to the kind of event (trauma vs. loss). Subjective reports of stress generally did not associate with immune change. In some cases, physical vulnerability as a function of age or disease also increased vulnerability to immune change during stressors.Since the dawn of time, organisms have been subject to evolutionary pressure from the environment. The ability to respond to environmental threats or stressors such as predation or natural disaster enhanced survival and therefore reproductive capacity, and physiological responses that supported such responses could be selected for. In mammals, these responses include changes that increase the delivery of oxygen and glucose to the heart and the large skeletal muscles. The result is physiological support for adaptive behaviors such as "fight or flight." Immune responses to stressful situations may be part of these adaptive responses because, in addition to the risk inherent in the situation (e.g., a predator), fighting and fleeing carries the risk of injury and subsequent entry of infectious agents into the bloodstream or skin. Any wound in the skin is likely to contain pathogens that could multiply and cause infection (Williams & Leaper, 1998). Stress-induced changes in the immune system that could accelerate wound repair and help prevent infections from taking hold would therefore be adaptive and selected along with other physiological changes that increased evolutionary fitness.Modern humans rarely encounter many of the stimuli that commonly evoked fight-or-flight responses for their ancestors, such as predation or inclement weather without protection. However, human physiological response continues to reflect the demands of earlier environments. Threats that do not require a physical response (e.g., academic exams) may therefore have physical consequences, including changes in the immune system. Indeed, over the past 30 years, more than 300 studies have been done on stress and immunity in humans, and together they have shown that psychological challenges are capable of modifying various features of the immune response. In this article we attempt to consolidate empirical knowledge about psychological stress and the human immune system through meta-analysis. Both the construct of stress and the human immune system are complex, and both could consume bookCorrespondence concerning this article should be addressed to Suzanne C. Segerstrom, Department of Ps...

Optimism is an individual difference variable that reflects the extent to which people hold generalized favorable expectancies for their future. Higher levels of optimism have been related prospectively to better subjective well-being in times of adversity or difficulty (i.e., controlling for previous well-being). Consistent with such findings, optimism has been linked to higher levels of engagement coping and lower levels of avoidance, or disengagement, coping. There is evidence that optimism is associated with taking proactive steps to protect one's health, whereas pessimism is associated with health-damaging behaviors. Consistent with such findings, optimism is also related to indicators of better physical health. The energetic, task-focused approach that optimists take to goals also relates to benefits in the socioeconomic world. Some evidence suggests that optimism relates to more persistence in educational efforts and to higher later income. Optimists also appear to fare better than pessimists in relationships. Although there are instances in which optimism fails to convey an advantage, and instances in which it may convey a disadvantage, those instances are relatively rare. In sum, the behavioral patterns of optimists appear to provide models of living for others to learn from.

The relation between dispositional optimism and better adjustment to diverse stressors may be attributable to optimism's effects on coping strategies. A meta-analytic review (K = 50, N = 11,629) examined the impact of dispositional optimism on coping. Dispositional optimism was found to be positively associated with approach coping strategies aiming to eliminate, reduce, or manage stressors or emotions (r = .17), and negatively associated with avoidance coping strategies seeking to ignore, avoid, or withdraw from stressors or emotions (r = -.21). Effect sizes were larger for the distinction between approach and avoidance coping strategies than for that between problem and emotion-focused coping. Meta-analytic findings also indicate that optimists may adjust their coping strategies to meet the demands of the stressors at hand, and that the optimism-coping relationship is strongest in English-speaking samples.

Experimental research reliably demonstrates that self-regulatory deficits are a consequence of prior self-regulatory effort. However, in naturalistic settings, although people know that they are sometimes vulnerable to saying, eating, or doing the wrong thing, they cannot accurately gauge their capacity to self-regulate at any given time. Because self-regulation and autonomic regulation colocalize in the brain, an autonomic measure, heart rate variability (HRV), could provide an index of self-regulatory strength and activity. During an experimental manipulation of self-regulation (eating carrots or cookies), HRV was elevated during high self-regulatory effort (eat carrots, resist cookies) compared with low self-regulatory effort (eat cookies, resist carrots). The experimental manipulation and higher HRV at baseline independently predicted persistence at a subsequent anagram task. HRV appears to index self-regulatory strength and effort, making it possible to study these phenomena in the field as well as the lab.

Although repetitive thought (RT) styles such as worry, rumination, and processing correlate positively, they have divergent effects on well-being, suggesting important dimensional variation. In Study 1, multidimensional scaling identified 2 dimensions--positive versus negative content valence and searching versus solving purpose--among students (N=978) who completed standard RT measures. In Study 2, students (N=100) sorted 25 descriptions of RT. Multidimensional scaling identified 4 dimensions, including valence and purpose. Content valence associated with valenced affect; solving associated with less aroused affect and less polarized appraisals of thought topics. In Study 3, valence and purpose of RT descriptions by women in a breast cancer prevention trial (N=62) predicted concurrent affect and psychological and physical well-being.

This study explored prospectively the effects of dispositional and situational optimism on mood (N = 90) and immune changes (N = 50) among law students in their first semester of study. Optimism was associated with better mood, higher numbers of helper T cells, and higher natural killer cell cytotoxicity. Avoidance coping partially accounted for the relationship between optimism and mood. Among the immune parameters, mood partially accounted for the optimism-helper T cell relationship, and perceived stress partially accounted for the optimism-cytotoxicity relationship. Individual differences in expectancies, appraisals, and mood may be important in understanding psychological and immune responses to stress. Recent years have witnessed substantial progress in understanding the contribution of psychosocial factors to physical health. One such factor, optimism, or the expectation of positive outcomes, has been tied to better physical health (Scheier et al., 1989) and more successful coping with health challenges (Carver et al., 1993; Stanton & Snider, 1993). However, the routes by which optimism might be associated with better health have not received systematic investigation. One plausible route is through effects on the immune system. Optimists cope differently with stressors, experience less negative mood, and may have more adaptive health behaviors, all of which could lead to better immune status. The present investigation examined optimism in the context of a major stressor, namely, the first year of law school, specifically examining relationships among optimism, mood, and immune changes. Coping and health behaviors were also examined as potential routes for these effects.

Dispositional optimism may be associated with growth of social and status resources by virtue of optimists' greater persistence and better performance. Conversely, resource growth may give people a more positive view of their future and increase optimism. Changes in dispositional optimism and resources over 10 years were examined in former law students (N = 61). More optimistic first-year law students made more money 10 years later, but income did not predict later optimism. More optimistic students did not have larger social networks 10 years later, but increases in social network size predicted increased optimism. These changes predicted mental and physical health. Dispositional optimism was less stable than many personality traits (r = .35), potentially because it is responsive to resource change.

Introduction The experience of cancer can be understood as a psychosocial transition, producing both positive and negative outcomes. Cognitive processing may facilitate psychological adjustment. Methods Fifty-five post-treatment, colorectal cancer survivors (M=65.9 years old; SD=12.7), an average of thirteen months post-diagnosis, were recruited from a state cancer registry and completed baseline and three-month questionnaires assessing dispositional (social desirability), cognitive processing (cognitive intrusions, cognitive rehearsal) and psychological adjustment variables (posttraumatic growth (PTG), posttraumatic stress disorder (PTSD) symptomatology, depression, anxiety, positive affectivity). Results PTSD symptomatology was positively associated with depression, anxiety and negatively associated with positive affectivity. In contrast, PTG scores were unrelated to PTSD symptomatology, depression, anxiety, and positive affectivity. In addition, PTG was independent of social desirability. Notably, after controlling for age at diagnosis and education, multiple regression analyses indicated cognitive processing (intrusions, rehearsal) was differentially predictive of psychological adjustment. Baseline cognitive intrusions predicted three-month PTSD symptomatology and there was a trend for baseline cognitive rehearsal predicting three-month PTG. Conclusions Additional research is needed to clarify the association between PTG and other indices of psychological adjustment, further delineate the nature of cognitive processing, and understand the trajectory of PTG over time for survivors with colorectal cancer.