Infectious agents

How are infectious agents relevant to schizophrenia?

Exposure to infection in utero is often cited as a risk factor for schizophrenia. Much focus is given to the influenza virus, despite studies yielding inconsistent findings. This topic summarises the available evidence for the risk of developing schizophrenia following exposure to influenza and other infectious agents, both before and after birth. The physiological mechanisms of any association of these infectious agents with schizophrenia are largely unclear. Also see the topic in Physical Features on markers for infectious agents in adults with schizophrenia.

What is the evidence for infectious agents as risk factors for schizophrenia?

Moderate to high quality evidence finds a medium-sized increased risk of schizophrenia in adulthood after having had a central nervous system viral infection in childhood.

Moderate quality evidence finds a small increase in levels of Toxoplasma gondii antibodies before the development of schizophrenia, and a medium-sized increase in recent-onset schizophrenia. Toxoplasma gondii is a parasitic protozoa, hosted by domestic cats and other warm-blooded animals, including humans. Toxoplasma gondii infection is usually of minor consequence to an adult but can have serious implications for a foetus.

Moderate to low quality evidence finds a medium-sized increased risk of schizophrenia in adulthood following exposure to infections in utero, particularly maternal upper respiratory tract, genital or reproductive infections, also herpes simplex virus and Toxoplasma gondii, but not influenza. There may also be an increased risk of schizophrenia following exposure to inflammatory cytokines TNF-a and IL-8 in utero.

March 2019

Last updated at: 5:00 am, 16th March 2019
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Fact Sheet Technical Commentary

NeuRA Libraries

Title Colour Legend:
Green - Topic summary is available.
Orange - Topic summary is being compiled.
Red - Topic summary has no current systematic review available.