Children whose mothers were exposed to high levels of lead during pregnancy are more than twice as likely to develop schizophrenia as adults, according to research presented at the annual meeting of the American Association for the Advancement of Science in Seattle.

During the 1960s, when lead was a common constituent in petrol, blood samples were routinely taken from pregnant American woman. A research team at Columbia University, New York, led by Dr Ezra Susser, used these preserved blood samples to compare the levels of lead in the mothers' blood with the incidence of schizophrenia that was reported in the adult.

“Results of the study provide the strongest evidence to date that schizophrenia may be caused by toxins or infections that damage the central nervous system under development in the fetus” (Toronto Star, 15 February 2004).

“It's the first time that any environmental toxin has been related to the later risk of schizophrenia”, Susser told BBC News online (14 February 2004).

“We think that people will now look at a variety of environmental toxins which can disrupt brain development, and see whether they are also related to the risk of schizophrenia” (BBC News online).

Susser suggests that lead interferes with the growth of nerve cells in the baby's brain during a critical developmental period in the womb (Health24.com, 16 February 2004)

More data are needed to confirm the findings but, as Susser explains, “If we can understand even one pathway of how schizophrenia is caused, we could open up the world of schizophrenia research to treatment and prevention.”