“Suggestible You” is the title of a book by Erik Vance. The subtitle is “The Curious Science of Your Brain’s Ability to Deceive, Transform, and Heal. This book is about the placebo response and related phenomena. This is the second post on this book.
Vance participated in an experiment in Luana Colloca’s laboratory on the campus of the National Institutes of Health. Dr. Colloca attached a variety of devices to Vance including two on his left hand. One device delivered the shock, the other, on his middle finger. She said that this device will tap into the A-B fibers in his hand that will occasionally interrupt the shocks, nearly cutting the pain altogether. As he explained it, the difference between the weak shock and the powerful shock would be that one has a crossing guard and the other does not. He was told that he would know which one was coming via a screen that will turn green when the A-B fibers are blocking the pain and red when they are not.
Vance said that the small shock feels like a pinprick or a pinch, but the bigger shock doesn’t feel like a bigger pinprick. He said that it’s more like a dull squeeze wrapped in fire, localized in his hand but seemingly all over his body as well. Colloca slowly increased the strength of the shock, working Vance up a scale of 1 to 10 (10 being the worst tolerable pain), testing his pain threshold. He agreed to a shock level of 6, although he said that this was very uncomfortable. He went through two rounds of 12 shocks each.
On the third round he noticed that the green (weak) shock) had gotten slightly worse—maybe from a 1 to a 2. He thinks there might be a problem with the shock blocker. They ran through 11 more trials and the torture session was over. When Colloca returned she told him his pain threshold was smack in the middle of the bell curve for pain, which is 100 hertz of electricity. She remarked that pain thresholds vary tremendously among individuals.
Then Colloca pointed to a sheet of paper showing Vance’s third round and dropped a surprise telling him, “In Block 3 we used green and red both at 100 hertz. You felt the green as less painful, compared to the red, when actually you received the same, and that is the placebo effect.” There never was any magic pain-lessening wire.
The question regarding why the placebo effect works was addressed by a team in Scotland in 1975. We do have a form of homemade opioids called endorphins. These endorphins play a number of tiles in our brain, such as regulating circadian rhythms, appetite and body temperature. They are the primary chemicals that make sex feel so good. Two neurologists, Jon Levine and Howard Fields conducted a simple experiment with people in pain after dental surgery.
The plan was to give a group of patients who had recently had a dental procedure either a placebo or naloxone. Naloxone blocks the endorphins. They told all of the patients that they were receiving a painkiller. As expected, many of those who got the placebo felt less pain, whereas the naloxone group felt miserable, as their own natural opioid (endorphin) generator was being blocked. When naloxone was given to the genuine placebo group, they also felt miserable. So this study does show that pain placebos work because the brain self-medicates with the opioid like drug endorphins.