Evidence is accumulating to support the theory that vitamin D deficiency during pregnancy, caused by a lack of sunlight, can alter the development of a child's brain in the womb.
The role of vitamin D in building healthy brains was ignored until researchers began to notice some strange trends. People who develop schizophrenia in Europe and North America are more likely to be born in the spring, and they are roughly four times more likely to be born to Afro-Caribbean immigrants living in northern countries.
The body needs sunlight to make vitamin D, and people with darker skin need more than people with pale skins. Scientists believe that there is a genetic predisposition to the development of schizophrenia, but John McGrath of the Queensland Center for Schizophrenia Research, thinks a lack of vitamin D during the early development of the fetus can increase the tendency to develop the disease in genetically susceptible people.
McGrath and neurobiologist Alan Mackay-Sim studied adult rats that had been deprived of vitamin D from conception. They found that they were more startled than normal rats by a loud noise that was preceded by a soft noise. Ventricles in the brains of the vitamin-deprived baby rats are unusually large, a feature seen in people with schizophrenia.
The researchers looked at the activity of thousands of genes in the brains of adult rats that had been deprived of vitamin D during gestation. They found that many genes had become less active, including three for brain receptors, as well as several that are involved in building nerve synapses.
"It's an exciting lead," says Fred Mendelsohn, of the Howard Florey Institute in Melbourne. But he says the new findings are a long way from decisively showing that a lack of vitamin D during pregnancy leads to schizophrenia.
McGrath agrees, but says the rat studies clearly show that too little vitamin D "does something nasty to the brain." He says we urgently need to find out exactly what that is, because vitamin D deficiency affects 12 per cent of women of childbearing age, according to a U.S. survey.
He says, "This should be a big wake-up call. We should find out quickly because [low vitamin D] could impact general intelligence, and have a whole range of neurological outcomes."
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