Researchers in Aberdeen and China have shown that prenatal exposure to famine increases the risk of schizophrenia.
Their findings published today (August 3) in the Journal of American Medical Association follows the collaboration of Shanghai Jiao Tong University and the University of Aberdeen on a study of a province which was one of the worst hit areas during the catastrophic 1959-1961 famine of China.
Researchers found that among births which occurred during the “Great Leap Forward” famine - which claimed the lives of around 30 million people - the risk of developing schizophrenia in later life significantly increased.
Their results support a separate study conducted earlier into the 1944-1945 Dutch Hunger Winter - when a sharp and time-limited decline in food intake occurred - which led to those most exposed showing a two-fold increased risk of schizophrenia.
The results in this study showed that among births that occurred during the famine years, the risk of developing schizophrenia in later life increased from 0.84% in 1959, to 2.15% in 1960 and 1.81% in 1961. These results were highly statistically significant.
David St Clair, Professor of Psychiatry at the University of Aberdeen, and a lifetime Professor at Shanghai Jiao Tong University in Shanghai, was one of the researchers who led the study.
He said: “The 1959-1961 Chinese famine was one of the 20th Century’s great horrors. It followed on the heels of immense social and economic upheaval often called the Great Leap Forward.
“We studied the Wuhu region of Anhui which was one of the most severely affected provinces. By the spring festival of 1959 Anhui was starving and people began to die in large numbers. The famine was relieved in the first months of 1961, but in other parts of China it continued throughout the year.
“We set out to test the hypothesis that prenatal exposure to famine would increase the rate of schizophrenia in adult life. Because 40 years had elapsed since the famine, individuals born during the famine would have passed through 80% to 90% of the lifetime risk of developing schizophrenia.
“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 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.”
Researchers say schizophrenia is almost certainly a multifactorial disorder with genetic and environmental elements contributing to overall risk. Schizophrenia is increasingly viewed as a neurodevelopmental disorder with environmental influences during early brain development modifying the risk of developing it.
Nutritional deficiency may increase the risk of schizophrenia by adversely affecting the developing fetal brain. The main evidence that prenatal nutritional deficiency comes from studies of the 1944-1945 Dutch Hunger Winter.
Nutritional restriction during the China famine encompassed all strata of society.
Researchers found that exposure to famine through early gestation is the critical period for increased risk of schizophrenia. Both sexes were equally affected and there was no difference in age of onset schizophrenia among those born before, during or after the famine years.