ADDICTION MAY BE IN THE GENES

Why would a talented and successful actor like Robert Downey Jr. repeatedly
risk his career for the sake of a drug-induced high? For many addicts like
Downey, the answer may lie not in their upbringing or the company they
keep, but in their genetic makeup.

And for drug users whose DNA plays a role in their habit, clinicians need
to turn their attention to new treatment options that address the genetics
of addiction.

Downey's very public yet personal struggle is a familiar story to millions
of Americans who struggle with addiction. A quarter of the U.S. adult
population is hooked on alcohol, cocaine, nicotine, amphetamines or some
other substance.

Through most of the 20th century, we viewed addiction largely as the
product of a flawed upbringing or bad character. Addicts deserved
punishment, not sympathy.

Studies comparing the lifestyles and habits of twins and adopted children
first suggested that addictive behavior has a hereditary component. We
began to consider the possibility that we might find the root cause of
addiction in our genetic makeup. A major breakthrough in understanding the
genetics of addiction came in 1990, when researchers first linked a gene
called DRD2--later nicknamed the "pleasure-seeking" gene--to severe alcoholism.

UCLA studies of brain tissue showed that individuals with the "A1
variation" of the DRD2 gene have significantly fewer dopamine receptors in
pleasure centers of the brain.

The findings suggest that many addicts use drugs, which increase brain
dopamine levels, to compensate for the deficiency in their neurological
pleasure system.

Subsequent studies linked the A1 variation of the DRD2 gene to cocaine,
amphetamine, heroin and nicotine addiction.

What does this all mean? It means simply that people with this genetic
trait are much more susceptible to addiction. In addition, they are more
likely to fall prey to the most severe forms of addiction. In fact, data
show that while only 10% of the general population in the United States has
the A1 variation of the DRD2 gene, it is found in about half of addicts.

Meanwhile, the implications for treatment programs are becoming
increasingly clear. A UCLA study of heroin addicts published this past
summer showed that a high percentage of heroin users who respond poorly to
traditional addiction treatment programs have the troublesome A1 variation
of the DRD2 gene.

And a recent study of alcoholics showed that patients with the same
"pleasure-seeking" trait responded well to treatment with a nonaddictive
drug that stimulates the dopamine receptors.

These findings demand that clinicians rethink treatment options for the
millions of drug-users who are genetically predisposed to addiction.

The implications carry additional weight in California, where
voter-approved Proposition 36 will divert tens of thousands of addicts a
year from the criminal justice system into treatment.

A simple cheek cell test of DNA can help differentiate hard-core, genetic
addicts from those who developed bad habits while socializing with bad crowds.

Drug abusers with a genetic propensity toward addiction typically require
one of a growing number of innovative prescription drug therapies to beat
their habit. Those without the gene more often respond best to counseling
that addresses environmental factors that led to their drug abuse.

The more we know about why the body craves drugs and the more we put that
knowledge to use, the more successful we will be in mitigating the heavy
toll that drug addiction takes on individuals, families and our society.