Ok, we all know what the placebo effect is supposed to be.
A researcher gives some people a drug. Other people get a sugar pill. The sugar pill people think they’re getting the drug, and some of them get better. From the 1950’s the number is supposed to be around 30%.
But the placebo effect varies far more widely than 30%. Some studies of pain show a startling placebo effect. Some drug studies have the placebo outperforming the drugs. (See the infamous St. Johns Wort vs. Zoloft vs. Nothing study. Nothing won, but St. Johns Wort got blamed.)
A meta-analysis of the sugar pill placebo effect found that in modern patients an active placebo was no more effective than no treatment, but the results varied depending on clinical interventions (study here).
But clearly a placebo effect exists. It is not the pill, but the doctor-patient relationship and patient expectation, that acts to improve a patients’ outcomes. More recently, researcher Benedetti “succeeded in mapping many of the biochemical reactions responsible for the placebo effect, uncovering a broad repertoire of self-healing responses. Placebo-activated opioids, for example, not only relieve pain; they also modulate heart rate and respiration. The neurotransmitter dopamine, when released by placebo treatment, helps improve motor function in Parkinson’s patients. Mechanisms like these can elevate mood, sharpen cognitive ability, alleviate digestive disorders, relieve insomnia, and limit the secretion of stress-related hormones like insulin and cortisol.” (Wired article).
The placebo effect from doctor-patient relationships and patient expectations has risen, in part possibly due to the massive marketing campaigns by pharmaceutical companies pre-selling their wares to consumers. (See Wired article).
It’s rising so quickly, the placebo effect at times exceeds the effect of the treatments themselves. In a recent analysis of placebo, no treatment, and treatment: “We found placebos often had as great a benefit over no treatment as treatments had over placebos. In trials with binary outcomes treatment effects were usually greater than placebo effects, and in trials with continuous outcomes and a low risk of bias placebo effects were greater than treatment effects.” (meta-analysis here).
Wait, are we saying that the placebo effect, by itself, has a significant, long-term healing capacity? That the effect is rising, rather than falling, and that a placebo effect alone is a worthwhile clinical goal over no treatment?
Ok, I’ve got all that. So what’s blowing my mind right now is a study on epilepsy in dogs. Animals, officially, don’t respond to the placebo effect. You aren’t supposed to be able to say to a dog: “Hey, this is medicine. It will make you better.” Well, maybe you could do it for something like pain with a doggie treat. But not something like epilepsy.
Here’s the conclusion of the study:
Results: Twenty-two of 28 (79%) dogs in the study that received placebo demonstrated a decrease in seizure frequency compared with baseline, and 8 (29%) could be considered responders, with a 50% or greater reduction in seizures. For the 3 trials evaluated, the average reduction in seizures during placebo administration relative to baseline was 26% (P= .0018), 29% (P= .17), and 46% (P= .01). (study abstract here).
So now dogs are demonstrating a significant placebo effect. Which means either dogs can think (which just made lots of dog lovers go “well, duh”) or the placebo effect is something that we really, really don’t understand.
One final thought from the Wired article. “geographic location alone could determine whether a drug bested placebo or crossed the futility boundary.” So social norms can determine whether your antidepressant or ulcer medication is effective?
How far off are we from the Krebiozen man? (blog post here).
Addition: We may be looking at a darker future as well. In a study of the placebo effect, women who did not comply by taking the placebo pill in a drug study died at almost twice the compliant patients‘ rate. Are we noceboing (negative placebo effect) ourselves to death?