Cocaine use found to ravage foetal brains

Cocaine use by pregnant women may result in the loss of more than half the brain cells in the infant's cerebral cortex, the highest level of the brain, say researchers.

They studied the brains of rhesus monkeys, but scholarly commentators say the findings could have implications for humans about actual physiological damage to the infant brain linked to prenatal cocaine use by the mother.

Half the eight monkeys in the experiment were born to mothers who got 20mg/kg of cocaine daily during the second trimester of pregnancy. The other half got no cocaine, but had similar diet and prenatal care.

The study, published in the Journal of Comparative Neurology, found that the cerebral cortex of the drug-treated monkeys contained about 60 per cent fewer neurons and was about 20 per cent smaller than that of the control monkeys.

"This is the first study that clearly shows the possibility that cocaine may affect the brain structure," said one of the study's authors, Dr Michael Lidow of the University of Maryland's Programme of Neuroscience.

"It shows that it could happen. This is a warning sign."

Generated during the second trimester of monkeys and humans, the cerebral cortex is largely responsible for higher brain functions, including sensation, voluntary muscle movement, thought, reasoning and memory.

Dr Lidow said exposure to cocaine prevented a substantial population of neurons from reaching their proper position in the cerebral cortex. For example, researchers know cells born on day 70 of the second trimester should go to position 5. But the study found that cocaine use blocked the cells from reaching their intended position.

"[We found] a lot [of neurons] actually stayed under the cortex in the white matter," Dr Lidow said, adding that the same effect has been observed in many schizophrenic patients.

Performing the study on monkeys made it easier to pinpoint the exact effect of cocaine on the brain, he said.

At three years, the monkeys were put to sleep and the cerebral hemispheres of both groups of animals were analysed for discernible differences.

Dr Lidow said further research was needed to determine how the findings might apply to humans.

Dr Barry Kosofsky, of Massachusetts General Hospital, and Dr Steven Hyman, of the National Institute of Mental Health, said the study might imply significant repercussions for the long-term neurological development of humans exposed to cocaine in the foetal stages.

- REUTERS