Can you tell me about the placebo effect? What is it?
The placebo effect is interesting, both historically and its mechanisms. The placebo effect really
was publicized as a result of a paper, I think in 1955, by somebody named Beecher, called
the "Powerful Placebo." He didn't do any new research, but he evaluated existing literature,
and he showed that for a variety of treatment modalities, about a third of the—for a variety
of different diseases states, about a third of the people that don't get treated get better.
That's the widely cited statistic where about 30 or 33 percent of people who get a placebo get better.
What do you mean by a placebo? What's a placebo?
Well, a placebo can be anything. If the treatment is a drug, a placebo can be something that
looks like the drug but doesn't contain the active ingredient. If the treatment consists
of the application of a machine like a hearing aid, a placebo would be something that looks
like that hearing aid...
Not turned on.
...but not turned on.
Yes, I see. Okay. How does the placebo effect work? What's the mechanism that allows you
to somehow have a physiological reaction even though there is no active drug or substance?
Well, when you say have a physiological reaction, the placebo effect is based on the patient's
report of them feeling better, and that's to be distinguished from a physiological reaction.
Although there are occasional isolated reports, there are really not good studies that have
stood up to replication that said that a placebo could have a physiological effect in terms
of producing tumor regression, for example. Rather, placebo effects are seen primarily
in two areas: analgesia—that is, pain relief—the patient reports that they're in less pain;
and depression—the patient reports less depression. These are all kinds of private
symptoms. They're only available to the patient. They're not available to anybody else outside
the patient, and so the patient has to report on them. In terms of public symptoms—blood
pressure, asthma symptoms, and things like that—placebo effects are much less pronounced.
Let me tell you about an interesting study that was done recently where patients who
had asthma had—there's a drug that's effective called "Albuterol." If patients get Albuterol,
you can demonstrate that the symptoms are released by changes, for example, in respiratory
volume. If you give half your patients—well, they gave a third of the patients nothing,
a third of the patients an Albuterol inhaler, and a third of the patients a placebo inhaler
that didn't have the active drug in it. The patients that got the placebo inhaler reported
they felt as good as the patients that got the actual active ingredient inhaler, and
both of them did better than the patients who got nothing, but if you actually measure
respiratory volume, it was only the patients who got the active Albuterol inhaler that performed better.
If the patient says they feel better, that's usually taken as evidence of the placebo effect,
but often if you measure whether they get better, and if you have some physiological
index, like respiratory parameters, then you'll find that there is no placebo effect.
Well, what does it mean for something to be a real effect, though? How would you react
to someone who said—well, even though you feel or you're reporting you have less depressive
symptoms, you don't really have less depressive symptoms because I gave you a placebo. But
that seems strange because I do have less. I am actually reporting feeling less...
You'll report it. People make mistakes, and their mistakes are understandable. Even with
the best diagnostic procedures, physicians that do appendix surgery are going to do unnecessary
surgery 10 to 20 percent of the time.
Because they don't want to make the type of error, which is to miss a burst.
Exactly. There are two types of mistakes, and one type of mistake is horrendous—that
is, missing an affected appendix. That would be a false negative. The other type of mistake,
a false positive, where the patient doesn't really have appendicitis but you do the surgery—well,
that's pretty bad you're doing unnecessary surgery, but it's not as bad as missing an
inflamed appendix. We understand the physician can make false positive errors, when considering
the cause and benefits of the different types of errors that they make.
The patient is in pain and gets a drug or gets a substance, which the physician assures
the patient will alleviate the pain. Just like the physician had a hard time diagnosing
the appendicitis, the patient has a hard time deciding whether the pain or the depression
or whatever is better or not. The pain is fluctuating in intensity, they have to somehow
compare the current level of pain with some presumably arithmetic mean of the pain in
the recent past and how recent past.
In average, yes.
It's a very difficult decision to make. If the patient in fact gets an inert substance
but doesn't know that, doesn't know whether they get an inert substance or placebo, then
if they make one type of mistake they'd be—suppose they actually got an active ingredient and
if they said, "I don't feel better," they'd be disputing the expertise of the physician;
they might be labeled a complainer; they might be prolonging their stay in the hospital...
So there are pressures on the patient to respond positively?
That's right. So placebo effect for a patient is a false positive response—that is, mistakenly
saying, "I feel better when I don't feel better," and it's as understandable as a false positive
response that the clinician makes in diagnosing appendicitis in a patient.
That's interesting. You said before that a placebo can be anything. Are there any factors
that affect the strength of a placebo effect?
I guess if the patient is more and more convinced that the substance that they get might be
one with active ingredients because, for example, it's very expensive or it comes from a bottle
that looks like an orthodox medicine bottle rather than...
Yes, or a big syringe.
That's right, yes. But I don't want you to think that all placebo effects are simply
false positive response. In fact, most of them and all of them in Beecher's case in
1955 are explained by a much simpler mechanism which is simply regression to the mean—that
is, most people that are sick approach a clinician, seek treatment, when they're sickest, and
most people who are sick get better.
They get better anyway.
My name is Shep. I think about anticipation.