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Brain network interaction reduced self control in smokers

Large-scale brain networks may work together to make quitting smoking more difficult, according to study findings from the University of Pennsylvania and the National Institute on Drug Abuse.

Smokers abstaining from nicotine for 24 hours had difficulty switching between the salience, executive control and default mode networks of the brain, which may increase the urge to smoke, according to researchers.

Caryn Lerman

Caryn Lerman, PhD, of the Center for Interdisciplinary Research on Nicotine Addiction in the department of psychiatry at the University of Pennsylvania, and colleagues constructed a within-subject functional MRI study in which they compared resting-state brain connections in 37 participants after 24 hours of smoking abstinence and after smoking satiety.

The researchers designed a resource allocation index (RAI), which contained data on the combined strength of interactions between the salience, executive control and default mode brain networks. Researchers examined the connection between RAI changes and changes in visual working memory.

Findings demonstrated that RAI decreased significantly when participants abstained from smoking compared with when they smoked at their usual rate (left hemisphere RAI, P=.002; right hemisphere RAI, P=.04). Further analysis revealed that change in right hemisphere RAI was negatively correlated with changes in smoking urge (P=.007), with larger decreases in RAI reflecting increased urges to smoke during abstinence.

In memory-based task performance, the researchers found that decreasing right hemisphere RAI was linked to participants giving correct answers more slowly (P=.08). When researchers interpreted activity in specific networks of the brain, the salience and default mode networks were more strongly coupled during smoking satiety than in abstinence.

The data supported the researchers’ theory that the inability to disengage from the brain’s default mode may be critical in establishing nicotine dependence.

“We believe that smokers who just quit have a more difficult time shifting gears from inward thoughts about how they feel to an outward focus on the tasks at hand. It's very important for people who are trying to quit to be able to maintain activity within the control network — to be able to shift from thinking about yourself and your inner state to focus on your more immediate goals and plan," Lerman said in a press release.

Disclosure: Lerman reported receiving research funding from Pfizer independent of this study.