Subj: Gene-link breakthrough may explain drug addiction

Date: Jul 13, 1998

Source: The Irish Independent

Gene-link breakthrough may explain drug addiction

By ROBERT MATTHEWS in London

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."