Gene for Drug Abuse Identified

Researchers have been able to identify a gene that increases risk for use and dependence on drugs. In a study appearing in the March 2002 issue of the Journal of Molecular Psychiatry, they report that the mu-opoid gene brings about increased risk for use and abuse of drugs in general and does not appear to be specific for any particular drug.

The new study followed up on work done in 1999 that found a relationship between alcohol dependence and the mu-opoid gene. By comparing gene patterns between alcoholics and normal volunteers, they discovered that alcoholics had an abundance of a particular form of the mu-opioid gene, the AA form, compared to non-alcoholics. However, since many alcoholics included in the 1999 study were also abusers of other substances, the researchers could not conclude that this particular gene configuration conferred increased risk specific to alcoholism or to drug abuse in general.

"The 1999 study suggested that mu-opioid was a part of the drug abuse story, but did not allow us to ask more specific questions about relationships to other drugs or the gene's impact in other groups such as smokers or social drinkers,” said Dr. John Schinka, professor of psychiatry at the University of South Florida (Tampa, USA).
"In the current study, we looked at several groups, including a group of normal volunteers who had never been smokers or drinkers and a group of alcoholics who also used other drugs.”

The new research showed that the AA configuration occurred even in individuals with no history of smoking or drinking. However, the frequency of the configuration increased in groups with any use of alcohol or cigarettes and occurred in almost 90% of individuals treated for abuse of several drugs. Dr. Schinka emphasized that mu-opioid is only one of several genes that produce risk for drug abuse. The search for other genes will continue, and studies will also address how mu-opioid might interact with other genes in increasing risk.

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