Are some cases of psychosis caused by microbial agents? A review of the evidence

Abstract

The infectious theory of psychosis, prominent early in the twentieth century, has recently received renewed scientific support. Evidence has accumulated that schizophrenia and bipolar disorder are complex diseases in which many predisposing genes interact with one or more environmental agents to cause symptoms. The protozoan Toxoplasma gondii and cytomegalovirus are discussed as examples of infectious agents that have been linked to schizophrenia and in which genes and infectious agents interact. Such infections may occur early in life and are thus consistent with neurodevelopmental as well as genetic theories of psychosis. The outstanding questions regarding infectious theories concern timing and causality. Attempts are underway to address the former by examining sera of individuals prior to the onset of illness and to address the latter by using antiinfective medications to treat individuals with psychosis. The identification of infectious agents associated with the etiopathogenesis of schizophrenia might lead to new methods for the diagnosis, treatment and prevention of this disorder.

Small intestinal inflammation following oral infection with Toxoplasma gondii does not occur exclusively in C57BL/6 mice: review of 70 reports from the literature

“…As a first step, the prevalence of antibodies against T. gondii could be determined in patients with IBD compared to well-selected control populations; a slightly but significantly higher seropositivity rate (based on Sabin-Feldman dye test results) has been observed previously in a small cohort of Crohn's patients over the age of 40 in Israel (Rattan et al 1986). Results of studies that include larger patient numbers should be especially interesting since an association of T. gondii infection (based on the presence of IgG antibodies) with psychiatric disorders has been suggested (Yolken & Torrey 2008). …”

Increased levels of IL-6 in the cerebrospinal fluid of patients with chronic schizophrenia — significance for activation of the kynurenine pathway

“…Epidemiological studies have shown that infections and autoimmune diseases are clin ic ally important risk factors for the development of schizo phrenia. [1][2][3] Furthermore, a recent study integrating results from a meta analysis of genome wide association studies in schizophrenia found that the most significant changes were observed in genetic loci related to the immune system. 4 Also, patients with schizophrenia show microglial activation, as re vealed by positron emission tomography.…”

Gastroenterology issues in schizophrenia: Why the gut matters

“…This causal interface most likely occurs during prenatal or early postnatal brain development when neurons are migrating and synapses are being formed and pruned. Abundant and converging evidence from both genetic and environmental studies points to immune system aberrations as contributing a substantial risk for development of the disorder [6][7][8][9][10].…”