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Neuropsychiatric disorders (i.e., mood disorders and schizophrenia) and inflammation are closely intertwined, and possibly powering each other in a bidirectional loop. Depression facilitates inflammatory reactions and inflammation promotes depression and other neuropsychiatric disorders. Patients with neuropsychiatric disorders exhibit all cardinal features of inflammation, including increased circulating levels of inflammatory inducers, activated sensors, and inflammatory mediators targeting all tissues. Inflammation may contribute to the pathophysiology and clinical progression of these disorders. Of note, proinflammatory cytokines modulate mood behavior and cognition by reducing brain monoamine levels, activating neuroendocrine responses, promoting excitotoxicity (increased glutamate levels), and impairing brain plasticity. What are the sources of this chronic inflammation? Increasing evidence indicates that changes in neuroendocrine regulation, metabolism, diet/microbiota, and negative health behaviors are important triggers of inflammation. Finally, recent data indicate that early-life stress is associated with overt inflammation prior to the development of neuropsychiatric disorders., (© 2018 New York Academy of Sciences.)

Aging continuously remodels the immune system, a process known as immunosenescence. Here, we review evidence of premature immunosenescence in younger individuals under conditions of chronic psychological stress, chronic inflammation, or exposure to certain persistent viral infections. Chronic stress may accelerate various features of immunosenescence by activating key allostatic systems, notably the hypothalamic-pituitary-adrenal axis and increased cortisol levels. Chronic stress is associated with thymic involution, blunted T cell proliferation, increased serum proinflammatory markers, and shorter telomere lengths. Human cytomegalovirus (CMV) infection has been implicated in accelerating immunosenescence by shrinking the T cell receptor repertoire and causing clonal expansion of senescent CD8(+) CD28(-) T cells with a proinflammatory profile. These factors increase inflammation associated with aging, or "inflammaging," particularly as it relates to etiology of several age-related diseases and increased mortality. Patients with rheumatoid arthritis have been shown to have several signatures of premature immunosenescence, including expansion of senescent T cells associated with cognitive impairment. We end by speculating that bipolar disorder can be considered as a model of accelerated aging because it has been associated with shortened telomeres, higher CMV IgG titers, and expansion of senescent and regulatory T cells., (© 2015 New York Academy of Sciences.)

This manuscript reviews current evidence suggesting that aging of the immune system (immunosenescence) may be closely related to chronic stress and stress factors. Healthy aging has been associated with emotional distress in parallel to increased cortisol to dehydroepiandrosterone (DHEA) ratio. The impaired DHEA secretion together with the increase of cortisol results in an enhanced exposure of lymphoid cells to deleterious glucocorticoid actions. The lack of appropriated growth hormone signaling during immunosenescence is also discussed. It follows that altered neuroendocrine functions could be underlying several immunosenescence features. Indeed, changes in both innate and adaptive immune responses during aging are also similarly reported during chronic glucocorticoid exposure. In addition, chronically stressed elderly subjects may be particularly at risk of stress-related pathology because of further alterations in both neuroendocrine and immune systems. The accelerated senescent features induced by chronic stress include higher oxidative stress, reduced telomere length, chronic glucocorticoid exposure, thymic involution, changes in cellular trafficking, reduced cell-mediated immunity, steroid resistance, and chronic low-grade inflammation. These senescent features are related to increased morbidity and mortality among chronically stressed elderly people. Overall, these data suggest that chronic stress leads to premature aging of key allostatic systems involved in the adaptation of the organisms to environmental changes. Stress management and psychosocial support may thus promote a better quality of life for elderly people and at the same time reduce hospitalization costs.