REVIEWEmotion and immunity
Introduction
Some studies indicate that anxiety and depression are associated with disease recurrence in patients with genital and oral herpes [1]. Emotional factors (e.g., depression) are thought to play a role in numerous diseases, including Graves disease, rheumatoid arthritis, systemic lupus erythematosus, asthma, and diabetes [2].
Psychosocial factors associated with decreased immune responsiveness produce states of arousal, anxiety, and negative affect 3, 4, 5, 6, 7. These psychological states have been linked to increased neural activity in limbic circuits involving the amygdala and the hippocampus (arousal and anxiety) 8, 9, as well as to imbalances in neocortical activity favoring the right hemisphere(negative affect) 10, 11, 12.
It has been suggested that an emotional state, such as anxiety and depression, could play a key role in triggering immune alterations 13, 14. Theoretically, it can be assumed that negative events (stressors) lead to negative affective states (distress), consequently producing alterations in human immunity [13]. However, mild, brief, and controllable states of challenged homeostasis could actually be perceived as pleasant or exciting, and could be positive stimuli for emotional and intellectual growth and development. The immune response has also been reported to be enhanced when the stressful condition is mild to moderate in intensity [15]. Thus, it is likely to be the more severe, protracted, and uncontrollable situations of psychological and physical distress that lead to overt disease states [16], apparently resulting from immunosuppression.
Immunosuppression has been reported in human subjects who experience symptoms of anxiety and depression in response to situations such as examinations, bereavement, separation, and divorce 17, 18, 19, 20, 21, 22, 23. In animals, immunosuppression has also been demonstrated in response to a variety of stressors 15, 17, 24.
The relationship between emotion and the hypothalamic–pituitary–adrenal (HPA) axis has been studied extensively. Dysregulation of the HPA axis is the best documented example of a neurobiological abnormality in depresson. The main findings have been an elevation of cortisol levels, often during the night 25, 26, and a relative resistence of cortisol suppression to dexamethasone administration 26, 27, 28. Thus, hypercortisolemia has been suggested as a possible explanation for reduced immune function in depressed individuals. However, dissociation between the HPA axis and immune function has been reported in depression, with the suggestion that corticotropin-releasing hormone (CRH) and corticoid hypersecretion are not directly responsible for immunosuppression in affective disorders 29, 30.
An anxiety disorder such as panic disorder is accompanied by an activation of the HPA axis, which seems to correlate with the degree of anxiety experienced by the patients. On the other hand, the decrease of anxiety after alprazolam therapy occurs in concert with the normalization of the HPA axis function [31]. In panic disorder, however, there may be a dissociation between HPA axis and immune systems. This hypothesis is reinforced by the observation that administration of CRH with the ensuing ACTH-cortisol hypersecretion failed to modify the lymphocyte proliferative response to PHA [31].
Several methods have been employed to obtain quantitative indices of an individual’s immune responsiveness 3, 7, 32, 33, 34, 35. The most frequently used methods include quantification of T-helper and T-suppressor lymphocyte subpopulations; measurement of the ability of lymphocytes to synthesize and release lymphokines; quantification of T-lymphocyte proliferation in response to mitogens such as phytohemagglutinin (PHA), pokeweed mitogen (PWM) and concanavaline A (Con A); quantification of the cytotoxic activity of natural killer cells and other lymphocytes; measurement of total immunoglobulin levels; and measurement of specific antibody titers.
Recently, several prospective studies have addressed the question of whether emotions are accompanied by reduced immune responsiveness [1]. These studies have initiated the following review on the relationship between emotion and immunity.
Section snippets
Depression and immunity
Many studies suggest that, compared with normal controls, patients with depression show reduced immune function in a variety of immune measures. Clinically significant levels of depression are associated with poorer immunocompetence in psychiatric populations. For example, in-patients suffering from depression have a poorer blastogenic response than nondepressed controls 36, 37. Depressed patients have also been shown to have a lower percentage of helper T-lymphocytes than nondepressed controls
Loneliness and immunity
Loneliness is also a construct related to depression. In separate studies, both medical students [32] and psychiatric patients suffering from loneliness [67] have been shown to have lower NK activity. Kiecolt-Glaser et al. 32, 67 assessed lymphocyte responses to PHA and PWM activity and reported that a subgroup of patients with high scores on the UCLA Loneliness Scale showed confluence of hypercortisolism, reduced lymphocyte responses to PHA, and decreased NK cell activity.
In a prospective
Anxiety and immunity
Whereas there are numerous immunological studies on depression, studies that examine the relationship between anxiety and immunity are sparse. Recurrent lesions of genital herpes were preceded by higher levels of anxiety and a concomitant blunting of T-cell blastogenesis [69]. In another study, lymphocyte response was found to correlate negatively with anxiety among hospitalized patients [70]. In a recent study [71], untreated patients with anxiety disorders showed significantly reduced
Humor and immunity
Although the relationship between humor and immune function is an interesting topic, there is limited research available. According to one study, salivary IgA concentration increased significantly after subjects viewed a humorous videotape but did not change significantly after viewing a didactic videotape [78]. Thus, enhancement of the immune system could be one link between anecdotal claims of the relationship between positive emotional state and healing.
Limitation in research on the relationship between emotion and immunity
The existing literature is highly controversial and fraught with methodologic problems. These problems limit the interpretation and the generalizability of most of the studies. The limitations include diagnostic heterogeneity, sample size, control group composition, and assay techniques [44]. In particular, diagnostic heterogeneity is a potential confounding element that interferes with the attempts to evaluate this body of research.
The sample sizes were small in a majority of the studies, and
Conclusion
Earlier studies have suggested that depression is associated with immunosuppression, but a recent literature review has revealed that many studies reached inconsistent or conflicting conclusions. Few studies have investigated the relationship between anxiety and immunity, in contrast to the numerous immunological studies on depression. Despite a few contradictory reports, a clinical level of anxiety seems to reduce immune function, whereas a subclinical level of anxiety seems to enhance immune
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Early and later life environmental enrichment affect specific antibody responses and blood leukocyte subpopulations in pigs
2020, Physiology and BehaviorCitation Excerpt :Limited living space, and the lack of materials to forage prevent pigs from expressing natural behaviours, leading to damaging behaviours like biting the tails and ears of pen mates [1], cognitive impairment [2, 3], and negative emotions [4, 5]. Stress can result in altered innate [6] and adaptive [7] immune functions, and also positive and negative emotions can trigger immune alterations [8, 9]. Environmental enrichment is defined as an increase of the biological relevance of captive environments by appropriate modifications (such as more space and, in the case of pigs, the provision of rooting substrates) resulting in an improvement of the biological functioning of captive animals [10].
Effects of environmental enrichment and regrouping on natural autoantibodies-binding danger and neural antigens in healthy pigs with different individual characteristics
2017, AnimalCitation Excerpt :Both acute and chronic stress have been shown to result in altered immune functions (Dhabhar, 2014). Moreover, psychosocial factors can affect functioning of the immune system (Dhabhar, 2014), as both a negative and a positive mood may trigger immune alterations (Koh, 1998). Conversely, evidence is accumulating that mood and behaviour are affected by immune reactivity, including autoimmune responses towards brain and neuro-endocrine structures (Maier and Watkins, 1998).
The Adverse Effects of Psychological Stress on Immunoregulatory Balance: Applications to Human Inflammatory Diseases
2011, Immunology and Allergy Clinics of North AmericaThe self-perceived symptom distress and health-related conditions associated with morning to evening diurnal cortisol patterns in outpatients with major depressive disorder
2010, PsychoneuroendocrinologyCitation Excerpt :The results indicate that, unlike the impact of depressive symptoms on cortisol, higher levels of anxiety are associated with steeper diurnal cortisol patterns. One mechanism of the body's defense to stress is enhanced immune function in response to subclinical anxiety levels (Koh, 1998). In this study, higher anxiety levels related to steeper diurnal cortisol patterns may show another natural reaction of the body under stress conditions.
Stress and wound healing
2007, Clinics in DermatologyImpairment of several immune functions in anxious women
2007, Journal of Psychosomatic ResearchCitation Excerpt :This last response is considered a transient phenomenon occurring prior to immune down-regulation, indicating the body's defense against stressors and thus dealing with state (discrete response to a specific threatening situation) anxiety as opposed to trait (general tendency to experience anxiety symptoms when faced with nondangerous situations) anxiety [4–7]. Nevertheless, research dealing with the relation of anxiety to immunity is scarce [5]. Cytokines are known to orchestrate the complex network of cellular interactions that regulate immune response.