Serotonin Transporter Gene Shown to Influence College Drinking Habits
Researchers have identified a genetic factor that may predispose
young people to harmful drinking habits. A team of scientists interviewed
college students about their alcohol consumption and then analyzed
their genetic profiles, or genotypes. They found that students who
shared a particular variant of the serotonin transporter gene (5HTT)
consumed more alcohol per occasion, more often drank expressly to
become inebriated, and were more likely to engage in binge drinking
than students without the variant. The study appears in the current
issue of the journal Alcohol and Alcoholism.
"This research provides important new evidence that the risk of developing
a maladaptive pattern of alcohol consumption is influenced by genetically
determined neurobiological differences that exert their effects during
young adulthood," says Ting-Kai Li, M.D., director of the National
Institute on Alcohol Abuse and Alcoholism (NIAAA).
NIAAA clinical investigators Paolo B. DePetrillo, M.D., and Research Fellow
Aryeh I. Herman B.A., along with researchers from George Washington University
in Washington, D.C., conducted the study of 262 male and female college
students and analyzed data from the largest homogenous group: 204 male
and female Caucasian college students aged 17 to 23 years. To assess the
frequency and patterns of alcohol consumption, the scientists asked all
the students a set of questions, for example, how many times in the past
two weeks they had engaged in binge drinking (five or more drinks for
men and four or more drinks for women on one occasion).
The research team also analyzed each student's genotype with a focus on
the 5-HTT gene, which is involved in recycling the chemical serotonin
after it is secreted into the synapse of a cell. The researchers determined
which students had long or short versions of this so-called serotonin
Everyone inherits two copies of each gene, one from each parent. There
are two normal variations, or polymorphisms, of the serotonin transporter
gene, labeled the long and the short variants. Most people are heterozygous,
that is, they have one copy of each variant, but about 30 percent of the
Caucasian population are homozygous (carry duplicate copies) of either
the long or the short version. This percentage varies depending on the
ethnic background of the individual.
The researchers found that the students who carried two copies of the
short version of 5-HTT were more likely to report troublesome drinking
patterns. Dr. DePetrillo says, "Our findings reveal a significant
association of the serotonin transporter promoter polymorphism with increased
alcohol consumption behavior in the students that we studied. Taken together
with other research, this finding suggests that genetically mediated differences
in serotonergic response play an important role in mediating patterns
of alcohol intake." The students with two copies of the short form
of the gene engaged more frequently in binge drinking, drank more often
to get drunk, and consumed more alcoholic drinks per occasion than did
students with the other genotypes.
Another difference the researchers observed was that students with at
least one copy of the long variant of the 5-HTT gene tended to consume
a smaller number of drinks at a sitting, even though they went out to
drink as often as the other students.
Why should the presence of the shorter gene variant make such a difference?
The authors speculate that, because individuals who are homozygous for
the short version are known to be at risk for higher levels of anxiety,
they may use alcohol to reduce tension. Further studies are needed to
understand the influence of the serotonin transporter gene on drinking
behavior, with special attention given to replication in other ethnic
The article "Serotonin transporter promoter polymorphism
and differences in alcohol consumption behavior in a college student
population" is published as a Rapid Communication at http://alcalc.oupjournals.org/.
The study will appear in the September printed issue of Alcohol
and Alcoholism (Volume 38, Number 5).
For an interview with Dr. DePetrillo, please telephone 301/496-9420. Additional
information about genetic and other areas of NIAAA research is available
from the NIAAA Press Office and at http://www.niaaa.nih.gov.
The National Institute on Alcohol Abuse and Alcoholism, a
component of the National Institutes of Health, U.S. Department of Health
and Human Services, conducts and supports approximately 90 percent of U.S.
research on the causes, consequences, prevention, and treatment of alcohol
abuse, alcoholism, and alcohol problems and disseminates research findings
to science, practitioner, policy making and general audiences.