A Brown-led study has identified a genetic variant that indicates an increased risk of alcohol abuse in adolescents. The study, led by Robert Miranda P'04, assistant professor of psychiatry and human behavior for research, focused on a receptor gene previously tied only to adult alcohol abuse.
The mutation — located on a gene known as the m-opioid receptor gene, or OPRM1 — could lead to a higher risk of alcohol misuse in adolescents and heightened sensitivity to the reinforcing effects of alcohol.
The study will help "shed some light" and "get a better handle on the etiology" of adolescent alcohol abuse from a genetic perspective, said Assistant Professor of Community Health Valerie Knopik, who co-authored the paper. Knopik said the study, which will appear in the January 2010 issue of Alcoholism: Clinical and Experimental Research, the official journal of the Research Society on Alcoholism and the International Society for Biomedical Research on Alcoholism, is significant because most literature on alcohol abuse has focused on adults.
The study involved 187 participants between the ages of 12 and 18 from "high-risk disadvantaged neighborhoods and the court system," Knopik said. The volunteers were asked to provide a genetic sample and complete a series of assessments.
The researchers searched for the OPRM1 gene mutation — called a polymorphism — and surveyed each participant to determine "alcohol use disorder diagnoses and other psychopathology," Miranda said. Those who exhibited the polymorphism were more likely to abuse alcohol.
"Our findings provide the first evidence to suggest that teenagers who carry a certain variant of the OPRM1 gene experience more alcohol-related problems," said Miranda, "and are more likely to meet diagnostic criteria for an alcohol-use disorder."
This variant was shown to enhance how adolescents feel while drinking more than in adolescents without it, which partly explains why they are more likely to develop alcohol-related problems.
These findings, however, are not the sole causes of alcohol-use disorders, and both Knopik and Miranda emphasized the importance of environmental factors.
Still, "the relative importance of environmental and genetic factors appears to shift considerably over the course of adolescence," Miranda said. The genetic mutation appears to play a larger role in determining alcohol abuse "once teenagers begin to drink," he said.
This research will extend into future studies "to replicate these findings in a larger sample of youth and to identify protective environmental factors that reduce genetic risk for alcoholism," Miranda said.
Drinking and alcohol abuse are "really complex behaviors," Knopik said. "The candidate gene is just one piece of tens, of hundreds, of thousands of genes" influencing the actions of adolescents.
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