Schizophrenia linked to mother’s lack of sunlight Feb 8, 2002
Your chances of developing schizophrenia depend on how sunny it was months before you were even born, suggests new research.
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 data for a link with schizophrenia is still controversial, but potentially worrying because vitamin D deficiency is so common.
Vitamin D’s role in building healthy brains had been largely ignored, until researchers began to spot some curious epidemiological 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 as likely to be born to Afro-Caribbean immigrants living in England as they are to have parents of other ethnic origins living in the same areas.
The body needs sunlight to make vitamin D, and people with darker skin need more than paler-skinned people. So such observations led John McGrath of the Queensland Centre for Schizophrenia Research in Wacol to propose that a lack of vitamin D during early development tips the balance towards schizophrenia in genetically susceptible people (New Scientist, 21 July 2001, p 38).
Now McGrath has completed studies on rats that add experimental meat to the epidemiological bones. With neurobiologist Alan Mackay-Sim of Griffith University in Queensland, McGrath has found that – just like humans with schizophrenia – adult rats deprived of vitamin D from conception are more startled than normal by a loud noise preceded by a soft noise.
Ventricles in the brains of vitamin-deprived baby rats are also unusually large, a feature seen in people with schizophrenia, they told the International Society for Developmental Neuroscience meeting in Sydney last week.
The researchers also used “gene chips” to look at the activity of thousands of genes in the brains of adult rats deprived of vitamin D during gestation. The chips revealed many genes had become less active, including three for brain receptors, and several that code for proteins involved in building nerve synapses.
“It’s an exciting lead,” says Fred Mendelsohn, director of the Howard Florey Institute for experimental physiology and medicine in Melbourne. But he and others point out that the new findings are a long way from decisively showing that a lack of vitamin D during pregnancy helps trigger schizophrenia.
McGrath agrees, but says the rat studies clearly show that too little vitamin D “does something nasty to the brain”. He argues that 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 large US survey.
“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,” says McGrath.
But he warns pregnant women not to take additional vitamin D until more is known about its role in development – too much of the vitamin may cause birth defects.