Aug 30 2009
Placebos and the Brain
Many benefits of bogus treatments can be chalked up the “the” placebo response. Trouble is, we don’t know a whole heck of a lot about placebo responses to treatments. How robust and perhaps even real are they?
In that second sentence I used the plural for placebo response intentionally. For the nature of a placebo response may differ when given as a different treatment for a different illness, etc. When we lump all placebo responses together, we may be combining different types of fruit. So to speak.
A few days ago news of a study into “the” placebo effect for pain control was released. The strongly scientific research looked into the actual brain mechanisms that could be responsible for “placebo analgesia.” The release nicely summarizes the background information -
Placebo analgesia refers to an individual’s relief from pain following administration of a chemically inert substance and is thought to be due to a person’s belief that a potent pain medication was administered. Endogenous opioids, which are naturally produced by the brain in small amounts and play a key role in the relief of pain and anxiety, have been implicated in placebo analgesia. Brain imaging studies have shown that placebo analgesia stimulates release of endogenous opioids from higher brain regions associated with pain modulation and is associated with a decrease in signals from pain-sensitive areas.
In the new study, a drug that blocks opioid signaling, naloxone, was used to determine whether endogenous opioids do indeed play a role.
The researchers found that naloxone reduced behavioral placebo effects as well as placebo-induced decreases in pain-related brain responses. Most importantly, they also observed that, under placebo, cortical areas interacted with brainstem structures implicated in pain control and that these interactions were dependent on endogenous opioids and were related to the strength of experienced placebo effects.
Certainly, the above doesn’t close the book on placebo analgesia. But thanks to the research we can more confidently say that this type of placebo does indeed precipitate real changes in the brain.
