Wednesday, September 06, 2006

OLDER men are far more likely to father autistic children

Since autism seems to be linked to high intelligence, these results may mean that smart older guys tend to have more children than dumb older guys

A study involving more than 100,000 children found that those born to fathers aged 40 and over were nearly six times more likely to suffer from autism and related disorders than those with a father under 30. Scientists from the Institute of Psychiatry at King's College, London and Mount Sinai School of Medicine in New York, said that their research supported the theory that men also have a "biological clock" when it comes to producing healthy babies.

They described the findings as "the first convincing evidence that advanced paternal age is a risk factor for autism spectrum disorder". However the authors could not find a link between a mother's advancing age and autism.

The exact causes of autism remain unknown, but cases of it and related conditions such as Asperger's syndrome - known collectively as autism spectrum disorders (ASDs) - have increased tenfold in the past two decades. They now affect the lives of more than half a million families in Britain. A recent study suggested that the rate could be as high as 116 ASD cases per 10,000 children...

The latest study, published in the Archives of General Psychiatry, analysed 132,271 Jewish children born during the 1980s in Israel. The researchers found that, if the father was aged 15 to 29 when the child was born, the risk of autism was 6 in every 10,000 children. If the father was 30 to 39, then 9 in 10,000 children suffered autism (1.6 times higher), going up to 32 in 10,000 (5.75 times higher) for fathers aged 40 to 49. The risk was even higher for older fathers.

"This research adds to our knowledge that men also have a biological clock when it comes to reproducing," Dr Reichenberg said. "The sample size for the over-50s was small, so we added it to the results for fathers aged over 40, but our research suggests that very old fathers have around nine times the risk. "The research shows a linear effect - with every ten years, the risk doubles."

The researchers emphasised that the results related to autism and could not necessarily be generalised to apply to related disorders such as Asperger's syndrome. But they added: "This data suggests a significant association between advancing paternal age and risk of ASD."

They said that there were several genetic factors which could be at play, including spontaneous mutations in sperm-producing cells, or discrepancies in how genes are expressed.

Although the fact that all the children were Jewish was a limitation of the study, Dr Reichenberg did not believe it affected the results. More research was needed to see if the findings were replicated across other racial and ethnic backgrounds.

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