Some smokers can ease cravings not only by lighting up and giving the brain a hit of nicotine — but also by just thinking they're getting the drug, even when they're not, new research has discovered.

The Center for BrainHealth at the University of Texas at Dallas took 24 established smokers into the lab for a double-blind study.

They were asked to smoke under four conditions. For two visits, they were given a nicotine-containing cigarette each time. On two other visits, they were given a non-nicotine placebo. Here is the breakdown:

  • They believed the cigarette contained nicotine but received a placebo.
  • They believed the cigarette did not contain nicotine but received a nicotine cigarette.
  • They believed the cigarette contained nicotine and received nicotine.
  • They believed the cigarette did not contain nicotine and received a placebo.

After smoking, the participants completed a "reward learning task" while undergoing a brain scan. They rated their levels of craving before smoking the cigarette and after the task, which involved a game of investing in the stock market.

Scientists used functional magnetic resonance imaging (fMRI) to capture neural activity in the insula cortex, a region of the brain that plays a role in diverse functions and is also associated with drug cravings and addiction.

The purpose of using the task was to help activate the brain's brain's dopamine system, a little like gambling, said Dr. Xiaosi Gu, assistant professor in the School of Behavioral and Brain Sciences and the study's lead author.

The scans showed significant neural activity that correlated to both craving and learning signals when participants smoked a nicotine cigarette and believed its nicotine content was genuine. However, smoking nicotine but believing it was a placebo did not produce the same brain signals.

Reduced cravings

The smokers who got the nicotine, or simply believed they did, reported reduced cravings and the scan recorded increased neural activity. 

'When they believed there is nicotine and they had nicotine, the craving correlated with these anterior insula activations — but when they did not believe so, that correlation was gone." Gu said.

"Even when they had nicotine, but did not believe there was nicotine, their brain did not respond [with higher neural activity] and they still reported as much craving as before," she said.

"Basically, you have nicotine and your brain is kind of on, but the twist here is you have to have nicotine, but also believe you have nicotine for the brain to be on," she said.

"So in other words, if you have nicotine, but did not think so — you thought you had some kind of placebo — then your brain is still off," Gu said.

While the biological pull of nicotine plays a key role in the addiction, a person's belief system can also exert a pharmacological effect, she said.

Not just about substance itself

Researchers hope the study, recently published in Frontiers in Psychiatry, will tell them more about the mechanism of addiction.

"It looks like addiction is not just about the substance itself, but also the belief you need the substance to have a normal daily life," Gu said.

She said the study shows why cognitive therapy is so important in changing a smoker's beliefs.