Prenatal exposure to famine increases risk of schizophrenia

07/28/05

People born during a famine in China have an increased risk of schizophrenia, consistent with previous research suggesting a link between fetal nutritional deficiency and schizophrenia, according to a study in the August 3 issue of JAMA, a theme issue on violence and human rights.

Schizophrenia is a common form of severe mental illness characterized by thought disorder, hallucinations, and delusions, as well a as deterioration of social functioning and social withdrawal, according to background information in the article. It is distributed worldwide with a lifetime risk of approximately 1 percent. Schizophrenia is increasingly viewed as a neurodevelopmental disorder with environmental influences during early brain development modifying risk of schizophrenia. These influences, none of which are yet firmly established, include fetal nutritional deficiency. A previous study found that there was twice the risk of schizophrenia among children conceived during a food shortage in Holland in 1944-1945. However, the number of cases in this study was small, and the findings were only modestly statistically significant.

David St. Clair, M.D., Ph.D., of Shanghai Jiao Tong University, Shanghai, China, and colleagues conducted a study to test the hypothesis that prenatal exposure to famine would increase the rate of schizophrenia in adult life by examining people who lived through a massive famine in China from 1959-1961. The risk of schizophrenia was examined in the Wuhu region of Anhui, one of the most affected provinces. Rates were compared among those born before, during, and after the famine years. All psychiatric case records for the years 1971 through 2001 were examined, and clinical and sociodemographic information on patients with schizophrenia was extracted by researchers.

The researchers found that birth rates (per 1,000) in Anhui decreased approximately 80 percent during the famine years from 28.28 in 1958 and 20.97 in 1959 to 8.61 in 1960 and 11.06 in 1961. Among births that occurred during the famine years, the risk of developing schizophrenia in later life increased from 0.84 percent in 1959 to 2.15 percent in 1960 and 1.81 percent in 1961. The death-adjusted risk was 2.3 times higher for those born in 1960 and 1.9 times higher for those born in 1961.

"Our study strongly supports the view that prenatal exposure to famine increases the risk of schizophrenia in later life. Using a much larger sample size with clear evidence of exposure, our findings are internally consistent and almost exactly replicate the Dutch findings. Since the two populations are ethnically and culturally distinct, the processes involved may apply in all populations undergoing famine," the authors conclude.

(JAMA. 2005; 294:557–562. Available pre-embargo to the media at www.jamamedia.org.)

Editor's Note: For information on funding/support, please see the JAMA article.

Editorial: Accumulating Evidence for Prenatal Nutritional Origins of Mental Disorders

In an accompanying editorial, Richard Neugebauer, Ph.D., M.P.H., of the New York State Psychiatric Institute and Columbia University, New York, examines the study by St. Clair et al.

"The Chinese study, while providing invaluable confirmation of the earlier Dutch work, unfortunately is not able to directly advance understanding of how nutrition may perturb prenatal neural development so as to influence risk for schizophrenia. The most pressing question from a public health and interventionist perspective is whether the relevant nutritional restriction of interest constitutes a global nutritional deficiency or a specific micronutrient deficiency. If the former, the implications of this work are confined largely to developing countries where severe protein-calorie malnutrition is common – certainly a matter of enormous public health and humanitarian concern in its own right. If the latter, the implications extend to developed and developing countries alike," writes Dr. Neugebauer.

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