GENE-LINK BREAKTHROUGH MAY EXPLAIN DRUG ADDICTION

SCIENTISTS have identified why some people may be genetically more
susceptible than others to becoming addicts if they experiment with drugs
or alcohol.

By discovering a key genetic sequence linked to drug and alcohol abuse, the
scientists believe they will be able to find ways to help at-risk
individuals avoid addiction.

Researchers have long suspected that genes play a key role in drug and
alcohol abuse, with studies of families of addicts hinting that a
disposition to addiction may be at least partly inherited.

Many now believe certain types of gene make brain cells more susceptible to
the effects of drugs, such as cocaine and heroin. These drugs home in on
so-called dopamine receptors on the surface of brain cells suggesting that
gene sequences linked to these receptors may be more common among drug
addicts.

A team at the University of Pittsburgh has now put this theory to the test
by looking for a genetic sequence known as DRD5, which animal studies have
linked to cocaine addiction.

Testing for the presence of the sequence among dozens of drug addicts, they
found the genetic sequence appeared in more than 80pc of abusers, compared
with barely half of the ordinary population.

Reporting their results in the journal Behavior Genetics, the team added
that more than one third of the drug addicts tested had inherited two
copies of the sequence from their parents, making the genetic effect
particularly strong. By contrast, only one in seven of non-addicts had both
copies. Almost half had none at all.

According to Dr Michael Vanyukov, head of the genetic research team at the
university's Centre for Education and Drug Abuse Research, the results
point strongly to a genetic influence on drug and alcohol abuse.

However, he stressed that this did not mean there was a "gene for drug
abuse," or that those with the gene were condemned to a life of addiction.

"This particular genetic sequence is pretty common in the population, so a
blood test would not be very helpful in identifying specific individuals,"
said Dr Vanyukov. "The real importance of this research is that it helps us
sift out the role of genes in drug abuse, and discover the role played by
environmental effects."

Dr Vanyukov added that the finding could lead to more sophisticated ways of
assessing a person's risk to drug abuse.

"At the moment, people are classified as either at risk or not at risk by
psychological tests which can be fairly arbitrary.

"We hope to develop a measure of risk that would include both relevant
genes and environmental factors, and develop preventative measures that
could offset even a high genetic predisposition to addiction."

British experts on addiction agreed that the discovery may prove useful in
identifying environmental factors behind drug addiction, but warned that
past claims of genetic links to behavioural traits had often proved premature.

"One of the problems with this type of research is that the findings turn
out to apply only to one group or population," said Dr Clare Stanford of
the University College, London.

"There have to be studies like this worldwide to confirm this kind of link."

Checked-by: Mike Gogulski