Rates of Adult Schizophrenia Following Prenatal Exposure to the Chinese Famine of 1959???1961

Abstract

Through adverse effects on the developing brain, maternal nutritional deficiency may increase the risk of schizophrenia apart from any genetic predisposition. After the Dutch Hunger Winter in 1944–1945, in which there was a major but time-limited decrease in food intake, the most exposed offspring had a twofold increase in the risk of becoming schizophrenic. The present investigators sought a similar association in the Wuhu region of Anhui, one of the Chinese provinces most affected during an extreme famine in the years 1959–1961. Rates of schizophrenia were obtained from psychiatric case records for the period 1971 through 2001. Researchers were unaware of exposure status. The Wuhu area has a population of 62 million. Up to the last decease, there has been little migration in or out of the region. The records review also took note of a family history of major mental illness. Birth rates declined by approximately 80% in 1960–1961. Mortality began to increase in 1959 and peaked in 1960. Overall mortality for Anhui was 12%, and for Wuhu and surrounding counties, 15%. The absolute number of cases of schizophrenia in children born during the famine years decreased but, as a proportion of total births in each year, the cumulative risk increased in the years 1960–1961 compared with the preceding and following years. The sexes were equally affected, and no difference in age at onset of schizophrenia was noted. Cumulative mortality rates were 35% to 40% in children conceived or born during the famine years. The figures for those born in the years just before the famine were 20% to 30%. The mortality-adjusted relative risk of schizophrenia was 2.3 (95% confidence interval [CI], 1.99–2.65) for children born in 1960 and 1.93 (95% CI, 1.68–2.23) for those born in 1961. There was no change in the proportion of familial cases in the years under study. These findings indicate strongly that prenatal exposure to famine conditions increases the risk of schizophrenia later in life. The increase in risk is nearly the same as in the Dutch studies, from an ethnically and culturally distinctive population, but it is based on a much larger sample and on clear evidence of exposure.