Selected infectious agents and risk of schizophrenia among U.S. military personnel.
OBJECTIVE
A number of studies have reported associations between Toxoplasma gondii (T. gondii) infection and the risk of schizophrenia. Most existing studies have used small populations and postdiagnosis specimens. As part of a larger research program, the authors conducted a hypothesis-generating case control study of T. gondii antibodies among individuals discharged from the U.S. military with a diagnosis of schizophrenia and serum specimens available from both before and after diagnosis.


METHODS
The patients (N=180) were military members who had been hospitalized and discharged from military service with a diagnosis of schizophrenia. Healthy comparison subjects (3:1 matched on several factors) were members of the military who were not discharged. The U.S. military routinely collects and stores serum specimens of military service members. The authors used microplate-enzyme immunoassay to measure immunoglobulin G (IgG) antibody levels to T. gondii, six herpes viruses, and influenza A and B viruses and immunoglobulin M (IgM) antibody levels to T. gondii in pre- and postdiagnosis serum specimens.


RESULTS
A significant positive association between the T. gondii IgG antibody and schizophrenia was found; the overall hazard ratio was 1.24. The association between IgG and schizophrenia varied by the time between the serum specimen collection and onset of illness.


CONCLUSIONS
The authors found significant associations between increased levels of scaled T. gondii IgG antibodies and schizophrenia for antibodies measured both prior to and after diagnosis.
Niebuhr
David W
DW
Department of Epidemiology, Division of Preventive Medicine, Walter Reed Army Institute of Research, 503 Robert Grant Ave., Silver Spring, MD 20901. David.Niebuhr@us.army.mil.
Millikan
Amy M
AM
Cowan
David N
DN
Yolken
Robert
R
Li
Yuanzhang
Y
Weber
Natalya S
NS
D000293:Adolescent; D000328:Adult; D000818:Animals; D000913:Antibodies, Protozoan / Q000032:analysis* / Q000097:blood / Q000276:immunology; D000914:Antibodies, Viral / Q000032:analysis / Q000276:immunology; D005260:Female; D006564:Herpesviridae / Q000276:immunology; D006801:Humans; D007124:Immunoenzyme Techniques / Q000706:statistics & numerical data; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D008297:Male; D008889:Military Personnel / Q000706:statistics & numerical data*; D012307:Risk Factors; D012559:Schizophrenia / Q000453:epidemiology / Q000209:etiology* / Q000276:immunology; D014122:Toxoplasma / Q000276:immunology*; D014123:Toxoplasmosis / Q000150:complications* / Q000453:epidemiology / Q000276:immunology; D014481:United States / Q000453:epidemiology
D000913:Antibodies, Protozoan; D000914:Antibodies, Viral; D007074:Immunoglobulin G