The researchers say their findings "go beyond the placebo effect," suggesting that beliefs alone can either eliminate or boost the brain effects of nicotine.
Published in the Proceedings of the National Academy of Sciences, the study revealed that participants who were told their cigarettes contained no nicotine showed less activity in areas of the brain that drive addiction - the reward-learning pathways, suggesting that an individual's beliefs about nicotine may influence a person's addiction to it.
Smoking is the leading preventable cause of death in the US. While it is other toxic agents in tobacco that are responsible for the damaging health effects of smoking, it is nicotine that causes tobacco addiction.
According to the research team, led by Read Montague, director of the Computational Psychiatry Unit at the Virginia Tech Carillon Research Institute, nicotine stimulates neural pathways in the brain associated with pleasure and reward, which is what drives nicotine addiction.
In their study, Montague and his team set out to investigate whether smokers' beliefs about nicotine, rather than their actual nicotine intake, could modify activity in reward-learning pathways of the brain.
The researchers point out that beliefs are known to contribute to the "placebo effect" - the idea that a "sham" treatment will have a positive effect based on the expectation that it will.
"A subject's belief that he or she is receiving a treatment could lead to observable improvement even in the absence of active drugs," the authors note. "These treatment effects are putatively accomplished by neurobiological processes usually associated with pharmacological actions of active drugs, even though active drugs are not administered."
Lower reward-learning activity for those who believed cigarettes were nicotine-free
The team tested whether a similar effect would be seen in 24 smokers who were divided into two groups. The subjects in one group were told the cigarettes they were about to smoke were nicotine free. In fact, both groups smoked conventional nicotine-containing cigarettes.
After smoking, all participants underwent functional magnetic resonance imaging (fMRI). During the brain scans, they played a reward-based learning game, in which they were given money, shown a historical stock price graph and asked to make an investment. This allowed the researchers to measure both their activity in the reward-learning pathways of the brain and the effect on choice behavior.
The study results revealed that the participants who believed they had smoked nicotine had much higher activity in their reward-learning pathways than those who believed their cigarettes were nicotine-free. Both groups also made very difference choices in the reward-based learning game.
These findings, the researchers say, "go beyond the placebo effect," suggesting that belief alone can either eliminate or boost the brain effects of nicotine. They add:
"These results provide compelling evidence demonstrating that prior beliefs about nicotine have the capacity to override the presence of a powerful neuroactive drug like nicotine by selectively modulating biophysically described processes in a fashion that correlates with measurable impact on learning and choice behavior."
Montague believes these findings may be useful for developing new treatments for addiction. "Just as drugs micromanage the belief state," he says, "maybe we can micromanage beliefs to better effect behavior change in addiction."Montague speaks more about the team's findings in the video below:
In an editorial linked to the study, Nora D. Volkow and Ruben Baler, of the National Institute on Drug Abuse (NIDA), say the research enhances understanding of why drug abusers perceive a drug to be more pleasurable when they expect it to be compared with when they do not.
"The report [...] represents an important step forward in this context because it offers new insights into how the power of belief modulates nicotine-driven learning signals related to nondrug rewards (money), as well as non-drug-related decisions (choice behavior)," they say. "More specifically, this work illuminates the mechanisms whereby belief can influence nonconscious learned association by modulating how the brain performs risk decisions while under the effects of nicotine."
Earlier this month, Medical News Today reported on a study published in JAMA, which found varenicline (brand name Chantix) could be useful for helping smokers to quit the habit gradually.