"This is the first time abstinence-induced changes in the working memory have been shown to accurately predict relapse in smokers," say the researchers.
Earlier this year, the researchers - from Penn Medicine in Philadelphia, PA - demonstrated in a study published in JAMA Psychiatry how people experiencing nicotine withdrawal have trouble shifting between brain networks that govern different modes of behaviors.
In particular, nicotine withdrawal makes it harder for people to shift into the "executive control network," which experts say allows individuals to exert more conscious self-control over cravings.
Now, the researchers say that their new study - published in the journal Neuropsychopharmacology - is the first to apply analysis of that brain activity to predicting relapse among smokers.
"This is the first time abstinence-induced changes in the working memory have been shown to accurately predict relapse in smokers," says senior author Prof. Caryn Lerman, a professor of Psychiatry and director of Penn's Center for Interdisciplinary Research on Nicotine Addiction.
Lead author James Loughead, PhD, associate professor of Psychiatry, adds:
"The neural response to quitting even after 1 day can give us valuable information that could inform new and existing personalized intervention strategies for smokers, which is greatly needed."
Using functional magnetic resonance imaging (fMRI), the team analyzed brain activity in 80 smokers seeking help for quitting. The participants were aged 18-65 and reported smoking more than 10 cigarettes a day for more than 6 months.
Each participant was scanned using fMRI immediately after smoking and again 24 hours after they initiated abstinence. A week after the quit date, participants also underwent a monitoring visit, which involved an assessment of smoking behavior and a urine test.
The monitoring visit and urine test occurred 7 days after the quit date because previous research shows that if a person is tobacco-free after 7 days, it is likely they will remain smoke-free for at least 6 months.
Relapsing smokers had reduced activity in 'working memory' brain region
During the study period, 19 smokers quit successfully and 61 relapsed. The researchers found that the smokers who relapsed had reduced activity in an area of the brain called the left dorsolateral prefrontal cortex.
The left dorsolateral prefrontal cortex controls executive functions such as working memory - an essential cognitive function for staying focused and completing tasks.
Another brain region, the posterior cingulate cortex, was found to have heightened activity in relapsed smokers. Typically, there is increased activity in the posterior cingulate cortex when an individual is in what experts call the "introspective" or "self-referential" state.
Using established clinical and behavioral predictors for relapse, the researchers were able to correctly predict relapse in 73% of cases using a model that took into account withdrawal symptoms, demographic and smoking history. They were also able to predict relapse in 67% of cases using a model that looked only at demographic and smoking history.
However, when the working memory data from the fMRI scans was applied as a predictor, the researchers found that the accuracy of the predictions jumped to a rate of 81%.
The researchers admit that it is not clinically or economically feasible to commonly adopt fMRI to predict smoking behaviors, but they suggest that the changes in working memory they have identified could provide potential targets for improved assessment models.
The researchers add that "predictive models can identify therapeutic targets for pharmacotherapies or neuroscience-based non-pharmacologic interventions to promote smoking cessation."