June 28, 2006

Infectious Agents in Schizophrenia and Bipolar Disorder

Since the beginning of the century, some scientists have theorized that bipolar disorder and even schizophrenia might be caused by an infection. This theory is supported with their similarities to other infectious diseases. AIDS, malaria, polio, and many more infectious diseases show a genetic predisposition, like both bipolar and schizophrenia. Even the neurotransmitter abnormalities provide support for this theory; alterations of dopamine, serotonin, and glutamate (neurotransmitters effected by bipolar and schizophrenia) have been seen in infectious diseases.

One study reviewed 108 psychiatric cases believed to be caused by CNS (central nervous system) viruses and concluded that 62 of those cases showed a specific virus. Syphilis, a STD, and Borrelia burgdorferi have been associated with producing schizophrenia like symptoms. More support for this theory is shown with over 200 studies that found an increased risk for developing bipolar and schizophrenia if born during the winter-spring seasons; which is consistent with an increased risk for other infectious diseases.

Dr. Robert Yolken and Dr. Fuller Torrey are examining 4 infectious agents they believe may be causes for schizophrenia and bipolar disorder (T gondii, HSV-1 and HSV-2, CMV, and endogenous retroviruses).

T gondii, one of the most prevalent human parasites, is hosted in cats and past to people through feces ingestion, or undercooked meat from animals that are infected. Exposure to it during pregnancy can cause CNS abnormalities in the fetus, and even stillbirths. A review of many studies found that persons with schizophrenia are 3 times more likely to be infected with T gondii than the control. There have even been reports of greater childhood exposure to cats in those suffering from schizophrenia.

Herpes Simplex Viruses (HSV-1 and HSV-2), usually spread by sexual contact, are fairly common infections in humans. A recent study found increased levels of HSV-2 in mothers of persons with schizophrenia or bipolar disorder. HSV-1 has been shown to increase cognitive dysfunction in those with schizophrenia and bipolar disorder, but not in the control.

Cytomegalovirus (CMV) is another herpes virus. People with schizophrenia have an increase in CMV antibodies, especially in those suffering with primarily negative symptoms. People with schizophrenia have also shown decrease in symptoms when treated with Val acyclovir, an antiviral medication used to treat herpes.

Endogenous Retroviruses are parts of DNA that join the human genome when infection in present. They can alter the transcription of genes and limit immune response. Studies have found that infection with T gondii and herpes viruses may activate the endogenous retroviruses, and be the connection between genetic abnormalities and infectious diseases in causing psychiatric disorders.

More research is needed to know the true connection between bipolar and schizophrenia with infectious diseases. Dr. Robert Yolken and Dr. Fuller Torrey along with the Stanley Medical Research Institute are currently studying the effects of antibiotics and antiviral medications on schizophrenia and bipolar disorder. The hope is that in the future a vaccine could be created to protect against infections that lead to these 2 disorders.

Source Article: “Infectious Agents in Schizophrenia and Bipolar Disorder.” Psychiatric Times (http://www.psychiatrictimes.com), June 2006, Vol XXIII, No. 7.

Recent Abstracts of Interest:

"The catechol O-methyltransferase Val158Met polymorphism and herpes simplex virus type 1 infection are risk factors for cognitive impairment in bipolar disorder: additive gene-environmental effects in a complex human psychiatric disorder." (http://blackwell-synergy.com) Bipolar Disorders, Volume 8 Page 124 - April 2006

"Human Endogenous Retrovirus Expression Profiles in Samples from Brains of Patients with Schizophrenia and Bipolar Disorders." Journal of Virology (http://jvi.asm.org/), September 2005, p. 10890-10901, Vol. 79, No. 17.


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