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Concept: Sickness behavior


The possible therapeutic impact of dietary changes on existing mental illness is largely unknown. Using a randomised controlled trial design, we aimed to investigate the efficacy of a dietary improvement program for the treatment of major depressive episodes.

Concepts: Randomized controlled trial, Schizophrenia, Major depressive disorder, Major depressive episode, Dysthymia, Depression, Suicide, Sickness behavior


When we contract an infection, we typically feel sick and behave accordingly. Symptoms of sickness behavior (SB) include anorexia, hypersomnia, depression, and reduced social interactions. SB affects species spanning from arthropods to vertebrates, is triggered nonspecifically by viruses, bacteria, and parasites, and is orchestrated by a complex network of cytokines and neuroendocrine pathways; clearly, it has been naturally selected. Nonetheless, SB seems evolutionarily costly: it promotes starvation and predation and reduces reproductive opportunities. How could SB persist? Former explanations focused on individual fitness, invoking improved resistance to pathogens. Could prevention of disease transmission, propagating in populations through kin selection, also contribute to SB?

Concepts: Immune system, Natural selection, Bacteria, Evolution, Symptoms, Evolutionary biology, Kin selection, Sickness behavior


Family caregivers of individuals with serious illness are at risk for depressive symptoms and depression. Hospice includes the provision of support services for family caregivers, yet evidence is limited regarding the effect of hospice use on depressive symptoms among surviving caregivers.

Concepts: Family, Major depressive disorder, Depression, Family Caregiver Alliance, Sickness behavior, Great Depression


Sickness behavior is characterized by lethargy, reduced appetite, anhedonia and anxiety. It can be induced in experimental animals by bacterial endotoxin, lipopolysaccharide (LPS). We investigated the impact of intracerebroventricular agmatine injections (5 - 20 μg/rat, icv) on sickness behavior induced by LPS (100 μg/rat, ip) in rats. Rats challenged with LPS demonstrated hyperthermia, anorexia, anxiety, depression like phenomenon and reduction in body weights. Additionally, mediators of sickness behaviors, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) level in LPS treated rat serum were also increased. The present study revealed that these LPS induced symptoms of sickness behavior including anorexia were normalized by pretreatment with agmatine. The IL-6 and TNF-α serum levels were also normalized in agmatine pretreated rats. It is anticipated that agmatine may suppress LPS induced sickness behavior by inhibiting proinflammatory pathway and/or activity circuitry in brain. This study suggests that agmatine may be important therapeutic target in the treatment of anorexia and other neurological abnormalities associated with bacterial infection.

Concepts: Inflammation, Psychology, Infection, Symptoms, Fever, Sickness behavior, Anorexia


Cognitive dysfunction is a prevalent and disabling symptom of Major Depressive Disorder (MDD), and is often retained in the remitted stage of illness. Emerging evidence suggests that cognitive impairment may be associated with dysfunction in a number of psychosocial domains (e.g., workplace productivity, social relationships). The current study explored the relationship between cognition and psychosocial functioning in remitted MDD and in healthy controls.

Concepts: Major depressive disorder, Dysthymia, Depression, Sickness behavior


It is of considerable translational importance whether depression is a form or a consequence of sickness behavior. Sickness behavior is a behavioral complex induced by infections and immune trauma and mediated by pro-inflammatory cytokines. It is an adaptive response that enhances recovery by conserving energy to combat acute inflammation. There are considerable phenomenological similarities between sickness behavior and depression, for example, behavioral inhibition, anorexia and weight loss, and melancholic (anhedonia), physio-somatic (fatigue, hyperalgesia, malaise), anxiety and neurocognitive symptoms. In clinical depression, however, a transition occurs to sensitization of immuno-inflammatory pathways, progressive damage by oxidative and nitrosative stress to lipids, proteins, and DNA, and autoimmune responses directed against self-epitopes. The latter mechanisms are the substrate of a neuroprogressive process, whereby multiple depressive episodes cause neural tissue damage and consequent functional and cognitive sequelae. Thus, shared immuno-inflammatory pathways underpin the physiology of sickness behavior and the pathophysiology of clinical depression explaining their partially overlapping phenomenology. Inflammation may provoke a Janus-faced response with a good, acute side, generating protective inflammation through sickness behavior and a bad, chronic side, for example, clinical depression, a lifelong disorder with positive feedback loops between (neuro)inflammation and (neuro)degenerative processes following less well defined triggers.

Concepts: Inflammation, Psychology, Symptoms, Major depressive disorder, Major depressive episode, Dysthymia, Sickness behavior, Hyperalgesia


Marijuana (MJ) use is common. Research shows risks for psychiatric illnesses, including major depressive disorder (MDD) and cognitive deficits with MJ use, particularly early-onset use. We investigated cognitive function, functional connectivity, and genetic risk with MDD alone and combined with MJ use, and differences between early-vs. late-onset/non-MJ use in youth.

Concepts: Psychology, Decision making, Major depressive disorder, Dysthymia, Depression, Sickness behavior


Perinatal depression is a neglected global health priority, affecting 10-15% of women in high-income countries and a greater proportion in low-income countries. Outcomes for children include cognitive, behavioural, and emotional difficulties and, in low-income settings, perinatal depression is associated with stunting and physical illness. In the Victorian Intergenerational Health Cohort Study (VIHCS), we aimed to assess the extent to which women with perinatal depressive symptoms had a history of mental health problems before conception.

Concepts: Psychology, Epidemiology, Illness, Educational psychology, Mental disorder, World Bank, Depression, Sickness behavior


With depressive disorders the leading source of disability globally, the identification of new targets for prevention and management is imperative. A rapidly emerging field of research suggests that the microbiome-gut-brain axis is of substantial relevance to mood and behaviour. Similarly, unhealthy diet has recently emerged as a significant correlate of and risk factor for depression. This review provides evidence for the gut microbiota as a key factor mediating the link between diet and depressive illness.

Concepts: Gut flora, Schizophrenia, Bipolar disorder, Major depressive disorder, Mood disorder, Mental status examination, Depression, Sickness behavior


As the incidence of malaria diminishes, a better understanding of nonmalarial fever is important for effective management of illness in children. In this study, we explored the spectrum of causes of fever in African children.

Concepts: Epidemiology, Malaria, Africa, Fever, Plasmodium malariae, Sickness behavior, University of St. La Salle