A study published last month in the American Journal of Psychiatry suggests an association between maternal exposure to toxoplasmosis and increased risk for developing schizophrenia in adult children.
The study, which evaluated archived blood samples from pregnant women who participated in a large birth cohort called the Child Health and Development Study (CHDS) from 1959–1967, was conducted by researchers at the New York State Psychiatric Institute and the Department of Epidemiology at the Mailman School of Public Health at Columbia University, in collaboration with the Kaiser Permanente Medical Care Plan, Northern California Region.
Toxoplasmosis is a parasitic infection that can develop from eating undercooked meat and unwashed fruits and vegetables, drinking contaminated water, or not washing one's hands after gardening or changing cat litter boxes. Researchers found a potential link between high maternal toxoplasmosis gondii antibody titers and development of schizophrenia spectrum disorders in the adult offspring. No association was found for moderate antibody titers. While active toxoplasmosis infection is known to adversely affect fetal brain development, this is the first suggestion of a possible association between an elevated maternal antibody to toxoplasmosis and the risk of schizophrenia.
"These findings underscore the value of prenatal serologic samples to document how maternal infectious disease exposures affect the development of adult disorders over time," said Alan Brown, MD, lead author and associate professor of clinical psychiatry and epidemiology at the New York State Psychiatric Institute, Columbia University and Mailman School of Public Health. Since publication of this study, another group presented similar findings at a recent scientific conference. Their study, based in Denmark, also suggests a potential link between elevated levels of maternal toxoplasmosis gondii antibody and increased risk for schizophrenia among adult offspring. Dr. Brown noted, "While it's as good an idea as ever to wash hands before eating and to cook meat thoroughly, these studies are too preliminary to lead to new public health recommendations."
The risk of schizophrenia spectrum disorders in the general population is about one percent. The increase related to high toxoplasma antibody suggested by the Columbia study would add another one to two percent to this risk.
"Evidence from this and previous studies leads us to consider that the increased risk for schizophrenia may not stem from exposure to a specific infectious disease, but from a mechanism secondary to infection, such as inflammation," said Ezra Susser, MD, DrPH, Anna Cheskis Gelman and Murray Charles Gelman Professor and chair of the Department of Epidemiology at the Mailman School of Public Health. Dr. Susser is also senior investigator of the Prenatal Determinants of Schizophrenia (PDS) study, and head of Epidemiology of Brain Disorders at the New York State Psychiatric Institute. He added, "The current findings, while intriguing, must be replicated in a larger sample before we can conclude that elevated toxoplasma antibody in a pregnant woman could predispose her unborn child to develop schizophrenia later in life."