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."
The PDS study is based in the Child Health and Development Study (CHDS) cohort initiated by Jacob Yerushalmy at the University of California, Berkeley, in 1959, in collaboration with Kaiser Permanente Medical Care Plan in Northern California (KPNC). The goal of the CHDS was to examine influences on outcomes of pregnancy and childhood health and development. The CHDS recruited nearly every pregnant woman under obstetric care from the Kaiser Foundation Health Plan (KFHP) in Alameda County, California. The 19,044 offspring of these women born between 1959 and 1967 were automatically enrolled in KFHP. In addition to collecting and storing blood sera samples, the CHDS study collected extensive data on the prenatal period, and conducted maternal interviews on family health history, maternal and paternal health habits, and maternal and paternal socio-demographic information. In 1997- 1999, the research team used electronic databases to identify adult CHDS offspring that might have developed schizophrenia during the period between January 1, 1981 and December 31, 1997. These individuals were invited to participate in a diagnostic interview, and those who participated and were confirmed to have schizophrenia or disorders in the schizophrenia spectrum, were then compared with carefully matched individuals from the CHDS who did not develop these disorders.
In August 2004, the researchers determined in the same cohort that prenatal exposure to influenza may increase the risk for schizophrenia years later. Both of these findings are part of the larger team PDS study, which examines prenatal infection, nutrition, chemical exposure, paternal age, and a range of other prenatal factors that influence schizophrenia risk.
The PDS research is one of a number of "life course studies" being overseen by Dr. Susser at the Mailman School. In addition to the CHDS study, Dr. Susser and his team are looking at large birth cohorts from the U.S., Israel, and Norway to observe the pathogenesis of chronic and acute diseases and their links to prenatal and postnatal exposure to environmental factors such as viruses and toxins.
The only accredited school of public health in New York City, and among the first in the nation, Columbia University's Mailman School of Public Health provides instruction and research opportunities to more than 850 graduate students in pursuit of masters and doctoral degrees. Its students and nearly 250 multi-disciplinary faculty engage in research and service in the city, nation, and around the world, concentrating on biostatistics, environmental health sciences, epidemiology, health policy and management, population and family health, and sociomedical sciences.
Founded in 1896, the New York State Psychiatric Institute (PI) continues to contribute importantly to knowledge about understanding and treating psychiatric disorder and is ranked among the best psychiatric research facilities in the world today. Noted for its research on depression and suicide, schizophrenia, anxiety and child psychiatric disorders, PI is also at the forefront of research dedicated to unraveling the brain's mysteries. Its scientists constitute the core of the Department of Psychiatry at Columbia University. In 2000, Dr. Eric Kandel was awarded the Nobel Prize in Physiology or Medicine for research in his labs at PI on the cellular basis of memory. www.nyspi.org
Founded in 1959 by Jacob Yerushalmy at the University of California, Berkeley, The Child Health and Development Studies (CHDS)( www.chdstudies.org) enrolled 15,000 families who were members of the Kaiser Permanente Medical Care Plan between 1959 and 1967. CHDS scientists discovered ways to make pregnancy safer for mothers and their babies. Now they are discovering connections between early life and cancer, heart disease, diabetes, fertility and mental illness. The National Institute of Child Health and Development of the National Institutes of Health makes this unique research possible through continuing support over 40 years. The CHDS is now a part of the Public Health Institute, Berkeley California.
Founded in 1966, the Kaiser Permanente Division of Research (www.dor.kaiser.org), located in Oakland, CA, conducts NIH- and foundation-supported epidemiologic and health services research with the joint aims of increasing understanding of determinants of health and disease and improving the quality and effectiveness of medical care. The Division of Research is part of the Northern California Region of Kaiser Permanente Medical Care Plan (www.kaiserpermanente.org), which is a non-profit, integrated health services delivery organization with over 8 million members nationally.. The Northern California Region of KP is the oldest and one of the largest medical care plans in the US, with more than 3 million members in the San Francisco Bay Area and northern California.