Smokers who kick the habit could be hard-wired for success, thanks to greater communication between two regions of the brain that may play a role in controlling the urge to reach for cigarettes, a US study suggests.
Researchers reviewed brain scans of smokers who tried to quit and found the people who succeeded had something in common: a stronger connection between the insula, home to urges and cravings, and the somatosensory cortex, which handles touch and motor control.
"The insula is believed to be where we are consciously aware of physical sensations, such as pain, disgust, craving and emotions," lead study author Merideth Addicott, a researcher in psychiatry and behavioural sciences at Duke University in Durham, North Carolina, said by email.
While more research is needed to understand how the connection between the two regions works, scientists believe the insula is responsible for sending information on cravings to other areas of the brain that then decide how to react.
"The somatosensory cortex is important for movement, and thus, control over behaviour, so it makes sense that it is also involved in smoking cessation," Addicott said.
To see what the brains looked like in smokers who quit, researchers took magnetic resonance imaging (MRI) scans of 85 people one month before they tried to stop smoking and then followed them for 10 weeks to see if they succeeded.
At the start of the study, participants typically smoked an average of 19 cigarettes a day and had been smoking for around 19 years. Their average age was 38, and slightly more than half of them were women.
While participants got nicotine patches to help them quit, they received little in the way of advice or additional cessation support.
During the study period, about half of the smokers managed to quit. The rest relapsed at some point, smoking at least one cigarette each day for one week.
One shortcoming of the study is that it relied on participants to truthfully report whether or not they smoked, and another drawback is the lack of repeated MRIs throughout the study period, the researchers acknowledge in the journal Neuropsychopharmacology.
Still, the findings highlight activity in the brain that might be targeted by future smoking cessation treatments, said Arthur Brody, director of the Greater Los Angeles VA Smoking Cessation Programs and a psychiatry professor at the University of California, Los Angeles.
"The finding is novel in that it is the first to link greater functional connectivity between the insula and the somatosensory cortex with an improved likelihood of quitting or minimizing smoking," Brody, who wasn't involved in the study, said by email. "If the results of the current study are replicated, studies to assess the effectiveness of somatic treatments that affect brain circuitry may certainly be warranted."
Many people don't respond to currently available treatments for smoking cessation, such as nicotine patches or drugs that target cravings or nicotine receptors in the brain, said Amy Janes, a psychiatry and addiction researcher at Harvard University in Cambridge, Massachusetts.
"Factors like genetics, duration of exposure to tobacco, stress, other drug use, and psychiatric or medical disorders can affect treatment success," Janes, who wasn't involved in the study, said by email. "The effectiveness of a specific treatment may depend on individual differences in factors like brain function and communication between brain regions."