The AGE
February 2, 2006

Danish blood samples which have been frozen for decades may hold the key to confirming Australian research suggesting vitamin D deficiency at conception and during pregnancy is linked to schizophrenia.

Neuroscientist Darryl Eyles will travel to Denmark next week to launch a study which has the potential to unlock a major risk factor for developing the debilitating mental disorder.

Dr Eyles presented the results of animal studies to the Australian Neuroscience Society meeting in Sydney this week which found depriving rats of vitamin D from the point of conception resulted in psychotic-like behaviours in their offspring.

"We found that they have abnormal responses to agents that induce psychosis in humans such as drugs like amphetamines," said Dr Eyles, of the Queensland Centre for Mental Health Research.

The rodents also had structural changes in their brains similar to those found in people with schizophrenia, which affects around one in 100 Australians.

However, Dr Eyles said if vitamin D was added to the diets of rats at the point of conception their offspring developed no such problems.

If the theory is right, and vitamin D exposure at conception and during pregnancy can reduce the risk of schizophrenia, the finding would have major public health implications for women planning to get pregnant.

The message will have more bite if Dr Eyles can show an association between low maternal vitamin D levels and later schizophrenia risk in humans.

He hopes to do that by comparing 16,000 blood samples taken from Danish babies 30 years ago and comparing them with meticulously kept records to determine whether those born with low vitamin D levels had a greater risk of developing schizophrenia in early adulthood.

"If we show that, I think it's going to be one of the biggest risk factor type findings in schizophrenia for a very long time," Dr Eyles said in an interview.

"If I'm able to do that, I'll be opening French champagne. "We will then be able to say there are compelling indicators that women considering becoming pregnant should ensure they have moderate exposure to sunlight or supplement their diets with vitamin D fortified dairy products before they conceive."

Such a finding would explain why people with schizophrenia are more likely to be born in winter or spring.

Vitamin D is formed in the skin due to moderate exposure to sunlight and can be supplemented in the diet.

Until recent years, it has been more associated with being important for normal bone development.

But low developmental vitamin D is also emerging as a candidate risk factor for later onset neuropsychotic disease, such as schizophrenia, and degenerative conditions like multiple sclerosis.

Psychiatrist Philip Mitchell, of the University of NSW, described the research as "very intriguing" but he said the real test would be in demonstrating that the association occurred in humans.

"It's certainly research that the field will be keeping an eye on," he said.

"But I think it's premature to be saying to women that they should be taking vitamin D during pregnancy to avoid their children developing schizophrenia.

"I don't think the evidence at this stage is that firm."