More than 90% of attempts to quit smoking, the leading cause of preventable deaths globally, result in relapse, so the search for new cessation aids is ongoing.
The researchers behind the new study suggest repetitive TMS (rTMS) offers a safe option for reducing nicotine craving in dependent smokers. The US Food and Drug Administration (FDA) has already approved TMS for the treatment of depression.
Xingbao Li and colleagues from the Medical University of South Carolina report their findings in the 15 April issue of the journal Biological Psychiatry.
They found that a single 15-minute session of rTMS directed at the prefrontal cortex area of the brain temporarily reduced cue-induced smoking craving in nicotine-dependent individuals.
TMS is a non-invasive procedure that uses magnetic fields to stimulate nerve cells in the brain through coils positioned near the forehead.
During TMS the patient does not have to be sedated or anesthetized. They can undergo the treatment while lying back in a chair, awake.
Nicotine craving arises because of the substance's effect on the brain's reward centers, and on the dopamine system. Nicotine withdrawal results in decreased activity of the dopamine system, which is closely linked to craving, relapse and continued use of nicotine.
The researchers targeted the rTMS at the left dorsolateral prefrontal cortex (DLPFC), a critical region in the brain's reward system.
For the study, they recruited 16 nicotine-dependent individuals and gave them two treatments about one week apart. On one visit they received a 15-minute session of TMS, and on the other visit, they received a sham treatment. This allowed the researchers to compare the effect of the intervention against a placebo.
None of the participants was seeking treatment to stop smoking when they were recruited, and they all smoked ten or more cigarettes a day.
They were asked to continue smoking as normal, but to abstain from smoking for two hours before the treatment sessions to ensure cravings.
The participants were exposed to smoking cues (eg smell of smoke or sight of a cigarette) before and after each treatment and rated their craving after each block of cue presentation.
The results showed that craving induced by smoking cues was temporarily but significantly reduced after participants received the real rTMS but not after the sham treatment.
The researchers also found that the reduction in craving was greatest in those participants with higher levels of nicotine use.
They conclude that more studies are now needed to explore rTMS as an aid to smoking cessation, and Li adds in a statement that the finding "opens the way for further exploration of the use of brain stimulation techniques in smoking cessation treatment".
John Krystal, Editor of Biological Psychiatry, notes that:
"One of the elegant aspects of this study is that it suggests that specific manipulations of particular brain circuits may help to protect smokers and possibly people with other addictions from relapsing."
Although the reduction in craving induced by the single TMS treatment was only temporary, the team believes repeated sessions would make the effect last longer and give smokers a good chance of quitting for good.
Li says the "TMS as used in this study is safe and is already FDA approved for treating depression".
In another study published recently, researchers at the George Washington University School of Public Health and Health Services found that walking for just 20 minutes a day can help teenage smokers cut down on their smoking habit.