Study shows what ‘craving’ looks like
Whether it’s by chewing gum, snacking on carrots, taking medication or going cold turkey, smokers looking to kick the habit must first find a way to overcome the powerful, addictive grip of nicotine.
Nearly 80 percent of smokers who try to quit relapse within a year, according to the National Institute on Drug Abuse. To better understand why, scientists have long studied nicotine’s affect on the brain. Previous research demonstrates that brain activity spikes when a smoker is shown smoking-related images or pictures of someone smoking, triggering the strong cravings that often lead to relapse. Far less, however, is known about how the human brain reacts to naturally arising, abstinence-induced cravings to the drug.
For the first time, a new study by researchers in Penn’s Abramson Cancer Center shows that cravings associated with nicotine withdrawal correspond with increased activity patterns in regions of the brain important to attention, behavioral control, memory, and reward. The findings, published in the Dec. 19 issue of The Journal of Neuroscience, give researchers a new method of predicting when a person is more or less likely to reach for a cigarette when hit with an urge to smoke.
“The craving assessments used in our study predict relapse in smoking cessation treatment,” says Caryn Lerman, director of the Transdisciplinary Tobacco Use Research Center and senior author of the paper. “If validated in larger studies, these results may have important clinical implications.”
For the study, researchers recruited 15 smokers, ages 18-55, who smoked at least 10 cigarettes a day for the prior 6 months. Each participant was scanned using arterial spin labeled perfusion magnetic resonance imaging (MRI) technology. John Detre, associate professor of Neurology at Penn and a co-author of the study, developed the use of MRI as a non-invasive technique for measuring cerebral blood flow volumes.
Participants were asked to smoke a cigarette within an hour of the first scan. On a separate date, they returned for a second scan, this time having abstained from smoking for 14 hours overnight.
By comparing the two scans, Lerman’s team could “see” cerebral blood flow changes during abstinence-induced cravings.
Although the use of MRI scans is currently limited to research and pharmaceutical development for nicotine dependence, Lerman’s study demonstrates the technology’s potential for use in identifying smokers at increased risk of relapse who would benefit from more intensive therapy.
“Neuroimaging technology could potentially be applied to personalize therapy in the same way genomics is being utilized,” she says.
The research, which was funded by the National Institute on Drug Abuse and the National Cancer Institute, could lead to future MRI studies that identify people most and least likely to benefit from new or existing smoking cessation medication. For example, a particular drug might be shown to reduce regional cerebral blood flow during abstinence in some but might not work in others. “It may give us an early signal” of the efficacy of a drug, Lerman says.
Meanwhile, other ongoing research projects at the Transdisciplinary Tobacco Use Research Center are looking at the genetic influences on why people start—and continue—smoking, and the effectiveness of tobacco dependence treatments.
“Smoking is the greatest preventable cause of cancer and other diseases. ...Our focus is on translating new discoveries in neuroscience, pharmacology and genetics with the goal of developing new and better treatments to help people to quit,” Lerman says.
Originally published on Jan. 24, 2008
