Science: Update

CAESAREAN BIRTHS may contribute to schizophrenia - in rats, at least. A team at McGill University, Montreal, found that adult rats born by the operation differed from controls born by natural means. The Caesarean rats were more affected by amphetamines and had a "far worse" response to having their tails pinched - which, New Scientist explains, is a "standard test for stress reactions".

The hormonal surges that occur during birth could be the explanation, suggests Patricia Boksa, who led the work. But the data is not directly applicable to humans, and natural human birth probably affects the brain more than rats' natural birth.

AMERICAN DOCTORS have admitted that they still don't know the best way to treat or even diagnose attention deficit disorder (ADD) in children, even though more than a million children in the US now take powerful amphetamine- like drugs to control their hyperactive behaviour.

A report from an expert panel chosen by the National Institutes of Health this week called ADD a "profound problem" that may affect between 3 and 5 per cent of all American schoolchildren. But a consistent, proven method of diagnosing and treating the disorder remains elusive, the experts said.

There is "no current validated diagnostic test" for ADD, said Dr David Kupfer, a University of Pittsburgh psychiatry professor who chaired the panel. And while some treatments are effective in the short term (principally drugs such as Ritalin) no study has examined their effect on children who take them for more than 14 months.

"IN THIS dark, brown sediment I saw a small, white speck," said Frank Kyte, a geophysicist at the University of California at Los Angeles, explaining how he found a fossilised piece of the huge asteroid thought to have wiped out the dinosaurs 65 million years ago. Professor Kyte found the piece while studying sediments 150 feet down in the north Pacific Ocean, he reported in this week's Nature.

Analysis of the 2mm-wide piece showed a high concentration of iridium, the metal whose presence in sediment layers first suggested an extraterrestrial explanation for the death of the dinosaurs.

LAST WEEK, in an article on autism, we used the example of a fictional character in one of Nick Hornby's novels to illustrate the type of obsessional activity seen by some scientists as part of an autistic-like spectrum of behaviour. We also stated that it was perhaps no coincidence that Mr Hornby has an autistic son. We would like to apologise to Mr Hornby and his family for the distress this has caused. We did not intend the article to be insensitive or offensive, and regret that it has caused Mr Hornby distress.