STUDY FINDS STIMULANTS CAN HEAD OFF ADDICTION

Giving Ritalin or other stimulants to children with attention deficit
hyperactivity disorder could reduce their chance of becoming drug
addicts in later life.

A study has shown that rats given Ritalin during pre-adolescence
undergo behavioural and neurological changes that make cocaine
unappealing and that this state lasts into adulthood.

Some researchers have suggested exposure to stimulants in adulthood
increases sensitivity to drugs of abuse, raising the possibility that
children treated with Ritalin might be at greater risk of drug abuse
later in life.

But Susan Andersen and colleagues at Harvard Medical School have
provided evidence against this idea by injecting pre-adolescent rats
with Ritalin and then examining their sensitivity to cocaine during
adulthood.

Using place conditioning - a procedure in which rats learn to
associate drug effects with particular environments - they found that
rats treated with Ritalin as juveniles spent less time in places
associated with cocaine use.

Rats given Ritalin in adulthood also spent less time in places
associated with cocaine than normal animals, but the change was not
as great as in the younger group, Dr Andersen said. "(Ritalin)
exposure in developing rats seems to decrease responsiveness to
cocaine's rewarding effects and increase responsiveness to its
aversive effects," she said.

The research is published in the current issue of the journal Nature
Neuroscience.

Daryl Efron, a paediatrician at Melbourne's Royal Children's
Hospital, said the research was good news for parents of children who
were treated with stimulants for the disorder.

"It really supports the clinical and epidemiological data that we
have had previously suggesting that children with ADHD who are
treated with Ritalin have less chance of substance abuse later in
life," he said.