GENETIC LINK TO HABITUAL DRUG USE FOUND

A LINK has been found between cocaine addiction and genes which control the
biological clock, scientists said yesterday.

The finding could lead to new drug addiction treatments and greater
understanding of the body’s internal clock mechanism, the scientists said.

University researchers made the discovery after giving repeated doses of
crack cocaine to fruit flies, which at basic levels are genetically similar
to humans.

When several genes were removed that play a critical role in the insects’
circadian rhythms (patterns of biological function based on a 24 hour cycle)
the flies failed to become sensitised to cocaine. Flies which retained the
genes eventually showed signs of sensitisation, characterised by intense
behaviour responses.

In humans, drug sensitisation is linked to heightened craving and psychosis.

The scientists, led by Dr Jay Hirsh at the University of Virginia in
Charlottesville in the United States published their findings yesterday in
the journal, Science.

Dr Hirsh said: ‘‘This opens up the field of drug studies to thinking about
how a totally unexpected set of genes functions in response to drugs.’’

For several years Dr Hirsh has used insect models to probe some of the brain
’s molecular mysteries, such as the circuitry involved in learning, memory
and muscle movement.

While researching communication pathways in the nervous systems of fruit
flies, Dr Hirsh hit on the idea of using cocaine to investigate fundamental
addiction mechanisms.

According to Dr Alan Leshner, director of America’s National Institute on
Drug Abuse: ‘‘This exciting new research has given us a clue to the specific
genetic mechanisms that influence vulnerability to addiction.”

“Once clear, these mechanisms could become the basis for predicting who is
most at risk for addiction, and thus become a major aid in preventing this
national health problem,’’ he said.