Researchers at the University of Iowa have identified certain genetic profiles that may be linked to a person’s risk for developing nicotine addiction and other psychological behaviors. Using a genome-wide scan, scientists analyzed blood samples from smokers versus nonsmokers and found similar genetic patterns among smokers that may one day be used as a genetic test to determine who may be more vulnerable to nicotine addiction.
“When you look at substance-abuse
disorders and antisocial behavior, these are the last vestiges of the belief
that mental impairments are related to moral will,” says Tracy Gunter, director
of forensic psychiatry at the
In the past few years, researchers around the world have zeroed in on various genetic regions believed to be involved in one’s vulnerability to addiction. Some have studied genes that control certain neurotransmitters in the brain, while others have looked at genes related to addictive traits like risk taking and impulsivity. Gunter and her colleagues chose to look at the genome as a whole and observe which genes are turned on and which turned off in people with a long history of smoking.
“One gene itself doesn’t tell you whether you have a disorder,” says Robert Philibert, a University of Iowa professor of psychiatry and the study’s lead author. “But if you measure 30 or 40, you come up with a good risk. So what we do is spot the biology.”
Gunter adds that few psychological behaviors exist alone. For example, people who smoke may also have panic disorders or depression, each of which may involve a number of different genes. “How do you sort that out?” Gunter asks. “Is a genetic test disorder- specific, or specific to a cluster of disorders? There may be some sites that contribute more to prediction of a disorder than other sites. In the years to come, could we prune that down? Maybe.”
There’s also a question of whether, once a person starts smoking, increased nicotine consumption causes certain genes to turn on or off. To that end, Philibert plans to run similar genome-wide analyses on younger people who have not yet started smoking but may have a family history of nicotine dependence. He will also analyze DNA samples from patients with single psychological diagnoses to obtain what he calls a “cleaner phenotype.”
“Transcriptional profiling in general, and this study in particular, are very promising ways of nominating candidate genes,” says Hinrichs. “I’m sure that these genes will now be on the map for other investigators.”