Friday, August 14, 2015

When you know its a placebo

As you know, I am a big proponent of placebos when used in the appropriate places. They can have pretty strong effects, have fewer side effects, and can cost a lot less.  For example, there is a lot of evidence that placebos work about as well as most of the anti-depressants on the market today.  Similar results have been found for over-the-counter pain relievers and cold medicines.

The one major hesitation I have for placebos is the ethics behind it. In my behavioral design work, I often stress that it is important that any nudges to the choice architecture need to be transparent.  Users need to know that their behavior is being influenced, why that influence supports their own personal goals and best interests, and give them the autonomy to refuse if they want. 

How can we do that with placebos?  Won’t placebos crash and burn if we have to tell users ahead of time that they are taking one? There are some people with enough top-down mental control that they can use placebos even when they know, but this is not a common trait.

It turns out, there is a way.  A recent study by the Cognitive and Affective Neuroscience Lab at Colorado University – Boulder found one.  What they did was apply a hot ceramic plate to the user’s arm (not enough to really burn them –we have ethics after all) and then give them a supposedly analgesic gel that was really a placebo. They secretly turned down the temperature of the ceramic plate so the user thought that it was the gel that was making their arm feel cooler.

After doing this four times, the users “learned” that the gel cooled down their arms.  Once this learning had occurred, the experimenters revealed that the gel was only a placebo. And it would still work.  After just one or two repetitions, it would not.

This makes scientific sense.  We have talked before about how hard it is to “unlearn” something.  There is a neuropsychological process to create a new memory or to strengthen an existing memory.  But there is not one to erase a memory.  There is reconsolidation to modify one, but that is not the same thing.

So if the link between the gel and the cooling (or the link from any placebo to its effects) is learned strongly enough (four repetitions in this case), the knowledge that it is a placebo doesn't “unlearn” the link that has been created in your brain. 

It seems to me that this is a nice middle ground that balances the effectiveness of the placebo and the need to be transparent when prescribing one.  Give the patient a chance to learn the placebo effect, then tell them it is a placebo, and then give them the autonomy to choose. 

Last minute update: 

There is a great term for how susceptible we are to the placebo effect – the placebome. It is a riff on the trend to name every biological attribute as an “-ome” of some sort. Genome was the real one.  Then we got the biome and microbiome and . . .

But seriously, it turns out that there are a few genes that predispose us to be more or less susceptible to the placebo effect.  So says researchers at the Beth Israel Deaconess Medical Center.

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