New Insights into Depressive Disorder with Respect to Low-Grade Inflammation and Fish Oil Intake.

Unipolar depression has been recognized as one of the major diseases by the World Health Organization in the 21st century. The etiology of depression is complicated and includes genetic factors, stress, aging, and special physical status (pregnancy, metabolic syndrome, and trauma). Numerous animal and human studies have demonstrated that n-3 polyunsaturated fatty acids (n-3 PUFAs) are highly correlated to cognition and depression. These nutritional antidepressants, including EPA and DHA, have a range of neurobiological activities contributing to their potential antidepressant effects. Our preclinical and clinical studies have indicated that n-3 PUFA supplementation in addition to standard antidepressant medications may provide synergistic neuroprotective and antioxidant/inflammatory effects. To translate our preliminary findings into clinical application, this paper reviews the existing evidence on the antidepressant effects of n-3 PUFAs and the potential underlying mechanisms, which include modulation of chronic lowgrade inflammation and the corresponding changes in peripheral blood immune biomarkers.

Acupuncture ameliorates inflammatory response in a chronic unpredictable stress rat model of depression.

Depression is one of the most common psychiatric disorders. Chronic inflammatory response has been viewed as a key factor in depression. Acupuncture in Chinese medicine has been shown to be an effective treatment for depression. In the present study, we investigated the mechanism underlying antidepressant effect of acupuncture. The rats were subjected to chronic unpredictable mild stress (CUMS) for 28days to induce depressive-like behaviors. Acupuncture treatment was applied once every other day during the 28-day stress period. The behavioral tests (body weight, sucrose consumption and locomotor activity) were performed. The expressions of nitric oxide (NO), prostaglandin E2 (PGE2), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and nuclear factor kappa B (NF-κB) were determined in the rat hippocampus and prefrontal cortex. CUMS induced depressive-like behavior in rats, which was alleviated by acupuncture treatment. The increased levels of NO, PGE2, iNOS and COX-2 induced by CUMS, were all significantly decreased in the hippocampus and prefrontal cortex by acupuncture. Moreover, acupuncture markedly inhibited the activation of NF-κB in rats. These findings showed that the antidepressant-like effect of acupuncture might be mediated by inhibition of inflammatory mediators via modulation of NF-κB in the brain regions.

Alteration of immune markers in a group of melancholic depressed patients and their response to electroconvulsive therapy.

BACKGROUND: Immune system dysfunction is implicated in the pathophysiology of major depression, and is hypothesized to normalize with successful treatment. We aimed to investigate immune dysfunction in melancholic depression and its response to ECT. METHODS: 55 melancholic depressed patients and 26 controls participated. 33 patients (60%) were referred for ECT. Blood samples were taken at baseline, one hour after the first ECT session, and 48h after ECT series completion. RESULTS: At baseline, melancholic depressed patients had significantly higher levels of the pro-inflammatory cytokine IL-6, and lower levels of the regulatory cytokine TGF-ß than controls. A significant surge in IL-6 levels was observed one hour after the first ECT session, but neither IL-6 nor TGF-ß levels normalized after completion of ECT series. Seventy per cent (n=23) of ECT recipients showed clinical response and 42% (n=10) reached remission. Neither IL-6 nor TGF-ß changes correlated with clinical improvement following ECT. No significant changes in IL-10, TNF-α and CRP levels were found in relation to melancholia or response to ECT. LIMITATIONS: As a naturalistic study, some potential confounders could not be eliminated or controlled, including medication use. CONCLUSIONS: Melancholic depressed patients demonstrated a peripheral increase in IL-6 and reduction in TGF-ß, which did not normalize despite clinical response to ECT. These findings may be consistent with emerging hypotheses of the role of inflammation in mediating neurotrophin expression. The implications of chronic inflammation in the melancholic depressed population for future medical health, particularly cardiovascular risk, are largely unknown and warrant further investigation.

Inflammation and Immune Regulation as Potential Drug Targets in Antidepressant Treatment.

Growing evidence supports a mutual relationship between inflammation and major depression. A variety of mechanisms are outlined, indicating how inflammation may be involved in the pathogenesis, course and treatment of major depression. In particular, this review addresses 1) inflammatory cytokines as markers of depression and potential predictors of treatment response, 2) findings that cytokines interact with antidepressants and non-pharmacological antidepressive therapies, such as electroconvulsive therapy, deep brain stimulation and physical activity, 3) the influence of cytokines on the cytochrome (CYP) p450-system and drug efflux transporters, and 4) how cascades of inflammation might serve as antidepressant drug targets. A number of clinical trials have focused on agents with immunmodulatory properties in the treatment of depression, of which this review covers nonsteroidal anti-inflammatory drugs (NSAIDs), cytokine inhibitors, ketamine, polyunsaturated fatty acids, statins and curcumin. A perspective is also provided on possible future immune targets for antidepressant therapy, such as toll-like receptor-inhibitors, glycogen synthase kinase-3 inhibitors, oleanolic acid analogs and minocycline. Concluding from the available data, markers of inflammation may become relevant factors for more personalised planning and prediction of response of antidepressant treatment strategies. Agents with anti-inflammatory properties have the potential to serve as clinically relevant antidepressants. Further studies are required to better define and identify subgroups of patients responsive to inflammatory agents as well as to define optimal time points for treatment onset and duration.

Assessing for unique immunomodulatory and neuroplastic profiles of physical activity subtypes: a focus on psychiatric disorders.

Physical activity (PA) is emerging as a safe and effective tool in the prevention and treatment of psychiatric disorders. PA subtypes include aerobic, resistance, flexibility, neuromotor (involving balance, agility and co-ordination), mind-body (e.g. tai chi, qi gong and yoga) and mixed type trainings. Evidence from clinical trials suggests that PA subtypes can have positive clinical effects, however the effects on the symptomatology may vary according to the PA subtype. It therefore stands to reason that various PA subtypes may modulate the immune system and neuroplastic processes differently. This systematic review aims to assess the immunomodulatory and neuroplastic profiles of various PA subtypes, particularly in unipolar depression and age-related cognitive decline (ARCD). The literature suggests several unique immunomodulatory and neuroplastic profiles for PA subtypes (i.e. resistance, aerobic and mind-body) in depression and ARCD. In depression, levels of various cytokines at baseline may predict treatment response to subtypes of PA and pharmacological agents. The pro-neuroplastic effects of resistance and aerobic PA in ARCD may differ due to variances in neurotrophin profiles. At this stage of literature in the field, it is difficult to draw firm conclusions on the specific immunomodulatory and neuroplastic pathways involved in these PA subtypes given of the small number of comparative studies and methodological heterogeneity between studies (e.g. study population age and illness severity, as well as duration and intensity of PA intervention). This important field requires well-designed, high-quality comparative studies to better describe unique immunomodulatory and neuroplastic profiles.

Synergistic relationships among stress, depression, and troubled relationships: insights from psychoneuroimmunology.

Stress and depression consistently elevate inflammation and are often experienced simultaneously, which is exemplified by people in troubled relationships. Troubled relationships also elevate inflammation, which may be partially explained by their ability to engender high levels of stress and depression. People who are stressed, depressed, or in troubled relationships are also at greater risk for health problems than their less distressed counterparts. Inflammation, a risk factor for a variety of age-related diseases including cardiovascular disease, Type II diabetes, metabolic syndrome, and frailty, may be one key mechanistic pathway linking distress to poor health. Obesity may further broaden the health implications of stress and depression; people who are stressed or depressed are often overweight, and adipose tissue is a major source of proinflammatory cytokines. Stress, depression, and troubled relationships may have synergistic inflammatory effects: loneliness, subclinical depression, and major depression enhance inflammatory responses to an acute stressful event. The relationship between distress and inflammation is bidirectional; depression enhances inflammation and inflammation promotes depression. Interesting questions emerge from this literature. For instance, some stressors may be more potent than others and thus may be more strongly linked to inflammation. In addition, it is possible that psychological and interpersonal resources may buffer the negative inflammatory effects of stress. Understanding the links among stress, depression, troubled relationships, and inflammation is an exciting area of research that may provide mechanistic insight into the links between distress and poor health.

Immune phenomena in neonates of women with depression during pregnancy: a case-control study.

OBJECTIVE: To evaluate the effects of major and minor depression during pregnancy on the maternal and neonatal immunities. METHODS: Peripheral venous blood from depressed women and cord venous blood from their neonates taken simultaneously and immediately after parturition were used. The serum levels of immunoglobulins IgG, IgM and IgA and complements C3 and C4 were determined through single radial immunodiffusion with the kits manufactured by the Biogen company (Mashhad, Iran). To reduce error, all the ring diameters were measured by one experimenter unaware of the study groups. The blood leukocyte and lymphocyte counts and lymphocyte percentage were determined with a H1 counter and for more accuracy also with a Hycel counter. RESULTS: The immune parameters of depressed women were not significantly different from controls. The lymphocyte counts in neonates of women with major and minor depression were increased, whereas ratio of the cord blood level of IgG to the maternal blood level of IgG in neonates of women with major depression were decreased compared to controls. CONCLUSIONS: Major depression during pregnancy reduces the prenatal transfer of IgG from mother to neonate. The low prenatal transfer of IgG may have clinical significance, because it can compromise immune competence in neonates.

Mechanistic explanations how cell-mediated immune activation, inflammation and oxidative and nitrosative stress pathways and their sequels and concomitants play a role in the pathophysiology of unipolar depression.

This paper reviews that cell-mediated-immune (CMI) activation and inflammation contribute to depressive symptoms, including anhedonia; anxiety-like behaviors; fatigue and somatic symptoms, e.g. illness behavior or malaise; and mild cognitive impairment (MCI). These effects are in part mediated by increased levels of pro-inflammatory cytokines (PICs), e.g. interleukin-1 (IL-1), IL-6 and tumor necrosis factor (TNF)α, and Th-1-derived cytokines, such as IL-2 and interferon (IFN)γ. Moreover, new pathways, i.e. concomitants and sequels of CMI activation and inflammation, were detected in depression: (1) Induction of indoleamine 2,3-dioxygenase (IDO) by IFNγ and some PICs is associated with depleted plasma tryptophan, which may interfere with brain 5-HT synthesis, and increased production of anxiogenic and depressogenic tryptophan catabolites. (2) Increased bacterial translocation may cause depression-like behaviors by activating the cytokine network, oxidative and nitrosative stress (O&NS) pathways and IDO. (3) Induction of O&NS causes damage to membrane ω3 PUFAs, functional proteins, DNA and mitochondria, and autoimmune responses directed against intracellular molecules that may cause dysfunctions in intracellular signaling. (4) Decreased levels of ω3 PUFAs and antioxidants, such as coenzyme Q10, glutathione peroxidase or zinc, are associated with an increased inflammatory potential; more oxidative damage; the onset of specific symptoms; and changes in the expression or functions of brain 5-HT and N-methyl-d-aspartate receptors. (5) All abovementioned factors cause neuroprogression, that is a combination of neurodegeneration, neuronal apoptosis, and lowered neurogenesis and neuroplasticity. It is concluded that depression may be the consequence of a complex interplay between CMI activation and inflammation and their sequels/concomitants which all together cause neuroprogression that further shapes the depression phenotype. Future research should employ high throughput technologies to collect genetic and gene expression and protein data from patients with depression and analyze these data by means of systems biology methods to define the dynamic interactions between the different cell signaling networks and O&NS pathways that cause depression.

Immune suppression and immune activation in depression.

Depression has been characterized as a disorder of both immune suppression and immune activation. Markers of impaired cellular immunity (decreased natural killer cell cytotoxicity) and inflammation (elevated IL-6, TNFα, and CRP) have been associated with depression. These immunological markers have been associated with other medical illnesses, suggesting that immune dysregulation may be a central feature common to both depression and to its frequent medical comorbidities. Yet the significant associations of findings of both immune suppression and immune activation with depression raise questions concerning the relationship between these two classes of immunological observations. Depressed populations are heterogeneous groups, and there may be differences in the immune profiles of populations that are more narrowly defined in terms of symptom profile and/or demographic features. There have been few reports concurrently investigating markers of immune suppression and immune activation in the same depressed individuals. An emerging pre-clinical literature suggests that chronic inflammation may directly contribute to the pathophysiology of immune suppression in the context of illnesses such as cancer and rheumatoid arthritis. This literature provides us with specific immunoregulatory mechanisms mediating these relationships that could also explain differences in immune disturbances between subsets of depressed individuals We propose a research agenda emphasizing the assessment of these immunoregulatory mechanisms in large samples of depressed subjects as a means to define the relationships among immune findings (suppression and/or activation) within the same depressed individuals and to characterize subsets of depressed subjects based on shared immune profiles. Such a program of research, building on and integrating our knowledge of the psychoneuroimmunology of depression, could lead to innovation in the assessment and treatment of depression and its medical comorbidities.

A psychoneuroimmunological review on cytokines involved in antidepressant treatment response.

OBJECTIVES: The literature exploring the role that cytokine functioning plays in the pathogenesis and treatment of depressive illness is reviewed. The review focuses on the influence of antidepressants on cytokines, and on how treatment response might be affected by genetic variants of cytokines. METHOD: The authors systematically reviewed the scientific literature on the subject over the last 20 years, searching PubMed, PsychInfo, and Cochrane databases. RESULTS: Antidepressants modulate cytokine functioning, and these mechanisms appear to directly influence treatment outcome in depression. Antidepressants appear to normalize serum levels of major inflammatory cytokines, including interleukin (IL)-1beta, IL-6, tumor necrosis factor alpha (TNF-alpha), and interferon gamma (IFN-gamma). Antidepressants are postulated to modulate cytokine functioning through their effects on intracellular cyclic adenosyl monophosphate (cAMP), serotonin metabolism, the hypothalamo-pituitary-adrenocortical (HPA) axis or through a direct action on neurogenesis. Preliminary research shows that cytokine genotypes and functioning may be able to help predict antidepressant treatment response. CONCLUSIONS: Current literature demonstrates an association between antidepressant action and cytokine functioning in major depression. Improved understanding of the specific pharmacologic and pharmacogenetic mechanisms is needed. Such knowledge may serve to enhance our understanding of depression, leading to promising new directions in the pathology, nosology, and treatment of depression.

Comorbidity of depressive and dermatologic disorders - therapeutic aspects.

Depressive disorders are more common in the population affected with dermatologic disorders. Comorbidity of depression and dermatologic disorders is around 30%. The correlation between depressive and dermatologic disorders still remains unclear. In psychodermatology three disorders are described: a) psychophysiological disorders (both disorders induced and maintained by stressors), b) secondary psychiatric disorders (mental disorder as a result of skin leasions and treatment) and c) primary psychiatric disorders (skin alterations as a result of mental disorders and treatment). In depression and dermatology disorders in which certain precipitating factors are required thereby causing alteration of the patient's immunological identity causing a combination of hereditary features and ones acquired through adaptation occur to cause the disorder to develop. The cytokines are vital in the regulation of the immunology response and are also mediators of non-infective inflammatory processes leading to recurrent hormonal secretion affecting the function of the vegetative and central nervous system leading to so called "sickness behaviour", marked by loss of appetite, anhedonia, anxiety, decrease of concentration and interest along with other changes which generate a picture of depressive disorder. Treatment of depressive and dermatologic disorders is complex and requires an integral therapeutic approach encompassing all aspects of both disorders and their comorbidity. Therefore therapeutic success lies in a team approach to the patient under the auspice of consultative-liason psychiatry by setting the frame for efficient collaboration and bridging the gap between the mental and the physical in everyday clinical practice.

[Immune activation and depression in the elderly]. / Immuunactivatie en depressie bij ouderen.

Besides the monoamine hypothesis, the stress hypothesis and the vascular hypothesis, the inflammatory hypothesis might be an etiological explanation for late-life depression. There is a growing amount of evidence to support this hypothesis. In animal studies, injection with cytokines was shown to cause behavioural changes ('sickness behaviour') similar to depressive symptoms in humans. Cytokine treatment of certain tumours and chronic hepatitis can also cause depressive symptoms. The prevalence of depression in patients with autoimmune diseases is higher than in the general population. Etanercept had a favourable effect on the depressive symptoms in patients with psoriasis, independent of improvement of physical symptoms. Cytokines affect the hypothalamus-pituitary-adrenal axis and cerebral neurotransmitter systems, both of which are thought to be involved in depression. Immune activation has been associated with depression, and several anti-depressive treatments affect immune parameters, although inconsistently. Since the aging process is associated with a dysregulation of the immune system, the inflammation hypothesis might be particularly true in late-life depression.

From psychosomatic to psychological medicine: what's the future?

PURPOSE OF REVIEW: Recent research findings into putative psychobiological mechanisms of emotional disorders as the future development of psychosomatic medicine are discussed. RECENT FINDINGS: Recent studies reinforce the communication between the immune and central nervous systems and identify the large set of peptide and nonpeptide neurotransmitters and ligands they share. Cytokines are seen as humoral mediators that may explain the interaction between endocrine and immune systems. The hypothalamic-pituitary axis has been investigated as part of the regulatory circuits that interact with autonomic regulation to expose immunologic processes related to stress or depression, and also to several diseases. Immune dysregulation and psychological distress have been linked to each other in disease, chronic stress, bereavement and other major life events. Research findings in depressive disorders and cancer may generate new theoretical paradigms in psychosomatic medicine. SUMMARY: The clinical understanding and management of distress or emotional disorders associated with physical illness may change in future because of the results of interdisciplinary research, where environmental factors will be integrated with psychological and biological systems, mainly of endocrine or neuroimmunological nature. The ultimate goal of psychosomatic medicine may be the integration of different levels of individual functioning on a systemic basis.

The effect of massage on cellular immunity, endocrine and psychological factors in women with breast cancer -- a randomized controlled clinical trial.

OBJECTIVES: The purpose of this study was to examine the effect of repeated effleurage massage treatments compared with a visit control group on circulating lymphocytes by studying the number and activity of peripheral blood NK cells, CD4+ and CD8+ T cells in women with breast cancer. Furthermore, the effect of repeated effleurage massage treatments on the levels of cortisol in saliva and oxytocin in plasma as well as degree anxiety, depression and quality of life was studied. DESIGN: A single centre, prospective, randomized, controlled trial. SETTINGS/LOCATION: The study was conducted in a radiation department, in a hospital in south-western Sweden. SUBJECTS: Twenty-two women (mean age=62) with breast cancer undergoing radiation were included in this study. INTERVENTIONS: The patients were randomly assigned to effleurage massage therapy (20 min of effleurage on ten occasions) or to control visits (ten 20-minute visits). OUTCOME MEASURES: Blood samples were collected before the first and last massage/control visit for analysis of peripheral blood NK, T cells and oxytocin. Saliva was analysed for cortisol. In addition, the patients completed the Hospital Anxiety and Depression Scale, Life Satisfaction Questionnaire and Spielbergers State Trait Anxiety Inventory prior to the first and last massage/control visit. RESULTS: Effleurage massage treatment had no significant effect on the number, frequencies or activation state of NK cells or CD4+ or CD8+ T cells. Furthermore, no significant changes between groups were detected on cortisol and oxytocin concentrations, anxiety, depression or quality of life. CONCLUSIONS: Significant effect of effleurage massage on cellular immunity, cortisol, oxytocin, anxiety, depression or quality of life could not be demonstrated in this study. Several possible explanations to the results of this study are discussed.

Depressive disorders and immunity: 20 years of progress and discovery.

Since the inception of Brain, Behavior and Immunity twenty years ago, many exciting developments have occurred regarding the relationship between depression and the immune system. These developments have increasingly put the field of psychoneuroimmunology into a clinical context with important translational implications. Initial studies focused on the impact of depression on relatively narrowly defined immunologic endpoints, which ultimately found their relevance in studies examining the effect of depression on immunologically-based diseases including infectious illnesses, autoimmune disorders, and cancer as well as more recently cardiovascular disease. Mechanistic studies have also greatly contributed to an understanding of those facets of depression, which might mediate these effects. More recently, the reciprocal influences of the immune system on the brain and behavior including depression have taken center stage. Increasing data now indicate that activated inflammatory processes can influence multiple aspects of CNS function including neurotransmitter metabolism, neuroendocrine function, and information processing leading to behavioral changes in humans that bespeak depression. These latter developments have intrigued scientists investigating the pathophysiology of depression and warrant consideration as some of the most exciting new developments in psychiatry in the past 20 years. What the future holds is a world of promise as multiple translational targets derived from the cytokine model of depression work their way into the clinical arena as drug targets for further development. Moreover, the work has served to instantiate brain-immune interactions as an essential component in psychiatric and medical co-morbidities and their impact on health and illness.

Cytokine, sickness behavior, and depression.

Sufficient evidence is now available to accept the concept that the brain recognizes cytokines as molecular signals of sickness. Clarifying the way the brain processes information generated by the innate immune system is accompanied by a progressive elucidation of the cellular and molecular components of the intricate system that mediates cytokine-induced sickness behavior. We are still far, however, from understanding the whole. Among the hundreds of genes that proinflammatory cytokines can induce in their cellular targets, only a handful has been examined functionally. In addition, a dynamic view of the cellular interactions that occur at the brain sites of cytokine production and action is missing, together with a clarification of the mechanisms that favor the transition toward pathology.

Cytokines as mediators of depression: what can we learn from animal studies?

It has recently been postulated that cytokines may cause depressive illness in man. This hypothesis is based on the following observations: 1. Treatment of patients with cytokines can produce symptoms of depression; 2. Activation of the immune system is observed in many depressed patients; 3. Depression occurs more frequently in those with medical disorders associated with immune dysfunction; 4. Activation of the immune system, and administration of endotoxin (LPS) or interleukin-1 (IL-1) to animals induces sickness behavior, which resembles depression, and chronic treatment with antidepressants has been shown to inhibit sickness behavior induced by LPS; 5. Several cytokines can activate the hypothalamo-pituitary-adrenocortical axis (HPAA), which is commonly activated in depressed patients; 6. Some cytokines activates cerebral noradrenergic systems, also commonly observed in depressed patients; 7. Some cytokines activate brain serotonergic systems, which have been implicated in major depressive illness and its treatment. The evidence for each of these tenets is reviewed and evaluated along with the effects of cytokines in classical animal tests of depression. Although certain sickness behaviors resemble the symptoms of depression, they are not identical and each has distinct features. Thus the value of sickness behavior as an animal model of major depressive disorder is limited, so that care should be taken in extrapolating results from the model to the human disorder. Nevertheless, the model may provide insight into the etiology and the mechanisms underlying some symptoms of major depressive disorder. It is concluded that immune activation and cytokines may be involved in depressive symptoms in some patients. However, cytokines do not appear to be essential mediators of depressive illness.

Chronic ACTH autoantibodies are a significant pathological factor in the disruption of the hypothalamic-pituitary-adrenal axis in chronic fatigue syndrome, anorexia nervosa and major depression.

Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is a commonly recognized feature of many pathological conditions. Abnormal adrenal responses to experimental manipulation have been well documented in patients suffering from chronic fatigue syndrome, anorexia nervosa and major depression. Yet no defect of any single organ, gland or brain region has been identified as a cause of these abnormalities. The disruption of the HPA axis that occurs in these conditions can be understood if an interfering factor is present in these patients. Evidence indicates that this interfering factor is adrenocorticotropin hormone (ACTH) autoantibodies. Chronic high levels of ACTH autoantibodies will significantly disrupt the HPA axis and force the body to compensate for an impaired cortisol response. The resulting effect of chronic ACTH autoantibody interference is the manifestation of adrenocortical insufficient symptoms and psychological disturbances. Some symptoms of chronic fatigue syndrome, anorexia nervosa and major depression, such as anxiety, are the adverse effects of mechanisms compensating for less effective ACTH due to autoantibodies. Furthermore, these patients engage in extraordinary behaviors, such as self-injury, to increase their cortisol levels. When this compensation is inadequate, symptoms of adrenocortical insufficiency appear. Corticosteroid supplements have been demonstrated to be an effective treatment for chronic fatigue syndrome, anorexia nervosa and major depression. It allows the patients to have the corticosteroids they require for daily functioning and daily stressors. This therapy will relieve the patients of their symptoms of adrenocortical insufficiency and permit their cortisol-stimulating mechanisms to operate at levels that will not cause pathological problems.

Unkind cytokines: current evidence for the potential role of cytokines in immune-mediated depression.

A great deal of interest has recently become focused on interactions between the nervous and the immune systems, including the potential for alterations in immune function to contribute to various psychiatric and neurologic disorders. Evidence suggests that cytokines may be involved in the development of depression. Immune-mediated mechanisms in the pathophysiology of some types of depression are reviewed from both clinical and animal studies and the difficulties inherent in studying the interplay of these two complex systems in the development of depression are described.

Stress and depression-induced immune dysfunction: implications for the development and progression of cancer.

The persistent activation of the hypothalamic-pituitary-adrenal axis and the sympathetic-adrenal-medullary axes in chronic stress response and in depression impairs the immune response and contributes to the development and progression of some types of cancer. This overview presents results from experimental animal models, human studies, and clinical evidence that various cellular and molecular immunological parameters are compromised in chronic stress and depression. At the cellular level, stressed and depressed patients had overall leukocytosis, high concentrations of circulating neutrophils, reduced mitogen-stimulated lymphocyte proliferation and neutrophil phagocytosis. At the molecular level, high levels of serum basal cortisol, acute phase proteins, specific antibodies against herpes simplex virus type 1 and Epstein Barr virus, plasma concentration of interleukins IL-1, IL-6, and TNF-alpha, and a shift in the balance of Th1 and Th2 immune response were observed. Both stress and depression were associated with the decreased cytotoxic T-cell and natural killer cell activities affecting the processes of the immune surveillance of tumours, and the events that modulate the development and the accumulation of somatic mutations and genomic instability. DNA damage, growth and angiogenic factors, proteases, matrix metalloproteinases, and reactive oxygen species were also related to the chronic stress response and depression. Behavioural strategies, psychological, and psychopharmacotherapeutic interventions that enhance effective coping and reduce affective distress showed beneficial effects in cancer patients. A better understanding of the bidirectional communication between the neuroendocrine and immune systems could contribute to novel clinical and treatment strategies in oncology.