Smokers suffering from nicotine withdrawal may have more trouble shifting their brain network, according to a recent study published in JAMA psychiatry.

Researchers from the Perelman School of Medicine at the University of Pennsylvania found that weakened brain connections may be the reason why people who try to quit smoking - and often say that kicking the habit makes the voice inside their head telling them to light up even louder -succumb to their nicotine cravings so often. Previous studies have found that up to 80 percent of those who attempt to quit smoking end up relapsing.

In the recent study, scientists found that people going through nicotine withdrawal showed weakened interconnectivity between certain large-scale networks in their brains: the default mode network, the executive control network, and the salience network. They posit that this weakened connectivity reduces smokers' ability to shift into or maintain greater influence from the executive control network, which may ultimately help maintain their quitting attempt.

"What we believe this means is 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," lead researcher Caryn Lerman said in a statement. "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."

For the study, researchers conducted brain scans on 37 healthy smokers (those who smoke more than 10 cigarettes a day) ages 19 to 61 using functional magnetic resonance imaging in two different sessions: 24 hours after biochemically confirmed abstinence and after smoking as usual.

Imaging showed a significantly weaker connectivity between the salience network and default mode network during abstinence, compared to when they are smoking, researchers said. Weakened connectivity during abstinence was also linked with increases in smoking urges, negative mood, and withdrawal symptoms, suggesting that this weaker internetwork connectivity may make it more difficult for people to quit.

Researchers said such connectivity could serve as a clinical biomarker to identify smokers who are most likely to respond to a particular treatment.

"Symptoms of withdrawal are related to changes in smokers' brains, as they adjust to being off of nicotine, and this study validates those experiences as having a biological basis," Lerman said. "The next step will be to identify in advance those smokers who will have more difficultly quitting and target more intensive treatments, based on brain activity and network connectivity."