SCOTT SIMON, host:
New study strengthens the idea that mental illness can be triggered by a deprived environment, including malnutrition. Researchers at the University of Aberdeen in Scotland have examined China's famine of 1959 to 1961 and found that children born during these years faced twice the risk at developing schizophrenia. The lead author of this study is Dr. David St. Clair. He joins us now from the studios of the BBC in Edinburgh.
Dr. St. Clair, thanks very much for being with us.
Dr. DAVID ST. CLAIR (University of Aberdeen): Pleasure.
SIMON: Does this study verify, as I understand it, an earlier study that links famine and mental illness?
Dr. ST. CLAIR: Yes. The first clue that this might be important came from a study conducted in Holland by Professor Susa(ph) from Columbia University who looked at adults who were born during a famine that took place in Holland at the end of the Second World War called the Dutch Hunger Winter. This was a short-lived famine and mothers exposed to pregnancy during that period had double the risk of having children develop schizophrenia than mothers who weren't exposed to malnutrition. So we really tried to replicate this study in a much bigger population. The Chinese famine was sadly one of the biggest famines that has ever taken place where millions starved to death, and so we were able to examine exposure over a two-year period in a much larger group of individuals, and the results that we get are remarkably similar to the results that the Columbia group got in the Dutch study.
SIMON: You refer to the obviously greatly different numbers in China. Could you give us some idea of specifically what you found in terms of the tens of millions of people who were affected?
Dr. ST. CLAIR: We took a population in Anhui province, which was one of the worst affected, where the mortality rate was about 15 to 20 percent of the population. There were fewer people with schizophrenia who were born during the famine years, but the number of births dropped dramatically, so if one looks at the ratio of people with schizophrenia to number of births, it rose to about 2 percent whereas in other years, it was less than 1 percent.
SIMON: Dr. St. Clair, what happens to a fetus when it's starved of nutrition?
Dr. ST. CLAIR: What malnutrition does to the developing fetal brain is not clear at the moment. It's not obviously something that one can study easily. We have some ideas that some micronutrients, specific requirements in one's food, may be crucial, but this is speculation at the moment and is work that we in Shanghai and Aberdeen and the group in Columbia are looking at closely.
SIMON: Would one draw a fair extrapolation of that, that malnutrition while somebody is a youngster growing up or, for that matter, even after they are grown can affect or even trigger some kind of genetic predisposition to schizophrenia?
Dr. ST. CLAIR: There's not really any evidence that malnutrition postnatally is a risk factor for schizophrenia or even a risk factor for increasing risk in those that are genetically predisposed to schizophrenia. It seems to be that the interaction, if it occurs, is happening in early brain development.
SIMON: What implications do you draw from the study of which you've been a part?
Dr. ST. CLAIR: I think that we would like to know why schizophrenia is around in human populations that--really in all populations that have been surveyed to date. We think that there must be some form of perhaps evolutionary advantage in having the risk genes, if not the formal illness itself, and that it's possible that these genes survive better in times of extreme stress such as famine conditions. This, again, is speculation, but it's, from a scientific point of view, a question that a lot of people are trying to address.
SIMON: Professor David St. Clair is a psychiatrist and geneticist at the University of Aberdeen in Scotland. The study was published in this month's Journal of the American Medical Association. Dr. St. Clair, thank you very much.
Dr. ST. CLAIR: Pleasure.
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