This is your brain on belief: How you feel about a drug may influence its effects on your brain

A person’s beliefs about a drug may influence the drug’s effects on their brain and behaviour, according to a study by researchers at Mount Sinai Health System in New York.The study, which was published in Nature Mental Health, focused on beliefs about nicotine. It examined whether beliefs about nicotine can change brain activity in a similar manner to the “dose-dependent” effects of pharmaceutical drugs.“We set out to investigate if human beliefs can modulate brain activities in a dose-dependent manner similar to what drugs can do, and found a high level of precision in how beliefs can influence the human brain,” Dr. Xiaosi Gu, an author of the study, said in a release. “This finding could be crucial for advancing our knowledge about the role of beliefs in addiction as well as a broad range of disorders and their treatments.”The researchers enlisted 23 nicotine-dependent adults from the Dallas-Fort Worth metropolitan area (three of the participants were excluded from the final analysis). The participants were given e-cigarettes and were told that the nicotine levels were either “low,” “medium” or “high,” even though the levels were actually the same. They were instructed to vape as much as they wished for 20 minutes. After vaping, they were asked how they would rate the strength of the nicotine on a 10-point scale.“Overall, participants’ perceived nicotine strength significantly increased as a function of instructed beliefs about nicotine dosage,” the authors wrote in the study.In order to ascertain how these beliefs mapped onto the brain, participants underwent functional magnetic resonance imaging (fMRI) while performing a “decision-making task known to engage neural circuits activated by nicotine,” according to the release. The task involved investing in simulated stock markets.The findings showed that the participants’ beliefs about the strength of the nicotine they consumed resulted in a dose-dependent effect in the thalamus, a key binding site for nicotine in the brain.A similar dose-dependent effect was also found in the functional connectivity between the thalamus and the ventromedial prefrontal cortex, a region of the brain important for decision-making and belief states, as explained in the press release.The results provide “compelling evidence” that subjective beliefs—and not only pharmacologic agents, as previously thought—affect biological substrates in the brain, the release noted.“Our findings provide a mechanistic explanation for the well-known variations in individual responses to drugs and suggest that subjective beliefs could be a target for the treatment of substance use disorders,” Dr. Gu said in the release.She added that the research team hopes to also study the effects of beliefs when it comes to other addictive drugs, including cannabis and alcohol, as well as therapeutic agents such as antidepressants and psychedelics.

This is your brain on belief: How you feel about a drug may influence its effects on your brain

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