Placebo

[Tony Williams]

I'm not sure that it matters what the mechanism is (certainly not from the patient's POV) as long as it works. After all, if it looks like a duck and quacks like a duck, then you can call it a duck....

[special_k]

I'm not sure that it matters what the mechanism is (certainly not from the patient's POV) as long as it works. After all, if it looks like a duck and quacks like a duck, then you can call it a duck....

(unless it's a duck-like non-duck thing)

I would agree, the difficulty is the frame of reference for measuring something like placebo. Many contributors are vexed by the fact that placebo defies measurement. It's like checking the markings on a ruler by measuring it against itself.

[Bob Lloyd]

There's an excellent paper here discussing the study of the placebo effect including the methodological problems and how they are addressed.

You might need to register (free) for PubMed:

http://www.ncbi.nlm.nih.gov/pmc/arti...tool=pmcentrez

[Croydon Bob]

It's like checking the markings on a ruler by measuring it against itself.

No it isn't.

Have you actually read this thread and looked at any of the links posted by various contributors? Your inability to understand is extraordinary. The comedy value has worn off however...

[special_k]

No it isn't.

Have you actually read this thread and looked at any of the links posted by various contributors? Your inability to understand is extraordinary. The comedy value has worn off however...

Well done, Bob, finally managed to say something useful.

[special_k]

One consistent feature of well conducted trials is that the control group do much better than would be predicted from observational data.

There is another aspect to this, which is that observational data tend to include any and all subjects, whereas in trials a selection process for subjects changes the profile. Somebody might be too sick, or too 'different' for some reason to take part in a trial, but have an experience that's relevant in a clinical setting nevertheless.

[Croydon Bob]

Well done, Bob, finally managed to say something useful.

Which is more than you have ever done...

[special_k]

How about looking at this in another way, which is to drop terms like Placebo, Psychosocial, and start from the broader premise that there is a cognitive component to homoeostasis? If somebody phones you up and tells you bad news, it triggers a response in your physiology - it has to, from cortisol response right on through. But the same bad news will affect somebody else in different ways.

Instead of trying to select a product with certain characteristics, then fool the patient with it, aren't we really trying to understand better that how the patient makes sense of their situation and the efforts to help, and the personal significance of events along the way, have a material effect on the outcome? There is nothing unethical in this, but it doesn't lead to easy one-size-fits-all solutions (yet).

The mechanistic studies point strongly to this, but I think we all accept that at this point in time the mental influence on disease is neither easy to understand, nor easy to quantify, but that it has potential value nevertheless.

Bob?

[Croydon Bob]

How about looking at this in another way, which is to drop terms like Placebo, Psychosocial, and start from the broader premise that there is a cognitive component to homoeostasis? If somebody phones you up and tells you bad news, it triggers a response in your physiology - it has to, from cortisol response right on through. But the same bad news will affect somebody else in different ways.

Instead of trying to select a product with certain characteristics, then fool the patient with it, aren't we really trying to understand better that how the patient makes sense of their situation and the efforts to help, and the personal significance of events along the way, have a material effect on the outcome? There is nothing unethical in this, but it doesn't lead to easy one-size-fits-all solutions (yet).

The mechanistic studies point strongly to this, but I think we all accept that at this point in time the mental influence on disease is neither easy to understand, nor easy to quantify, but that it has potential value nevertheless.

Bob?

It is rather bizarre that the same person can, one day, not know what a germ is or what a theory is (even after being pointed at explanations), and the next day writes "that there is a cognitive component to homoeostasis".

Either the above was copied from somewhere or s_k just sometimes pretends to be stupid to wind us up.


My answer to the question is: Placebo (and nocebo) have a meaning and describe an effect. There is no reason to drop them just because someone doesn't like or understand the placebo effect. The relevance of the connection between placebo and homeostatic imbalance that you are trying to draw is lost on me.

Yes, the mental influence on disease is neither easy to understand, nor easy to quantify, yes it has value. But, that doesn't change simple facts such as that placebo can make people feel less pain, feel happier, etc, but doesn't cure cancer or HIV. There are some very clear parameters within which we are working plus defined areas of uncertainty.

[special_k]

Bob, do you understand the phrase 'sensitive dependence on initial conditions'?

[Croydon Bob]

Bob, do you understand the phrase 'sensitive dependence on initial conditions'?

I know it is to do with choas theory and the Butterfly Effect, but the answer is "no" I don't understand it. How about you?

[special_k]

I know it is to do with choas theory and the Butterfly Effect, but the answer is "no" I don't understand it. How about you?

It means that the effect of actions varies according to the set-up of the system into which they are applied, and exactly where and when they are applied. A pencil standing on its point will fall one way or another, exactly which way depends on many things. The more precisely it is balance, the more that little things will affect the direction of fall.

In theory, the direction of fall of a perfectly upright pencil will be completely altered by a vanishingly small influence, even though it is not the tiny influence that actually pulls the pencil over. Fall it must, because when perfectly balanced, it cannot escape the influence of tiny things.

In other systems, it can mean that a large input can be completely lost, but it also means that a very small input can massively alter the outcome.

It stands in marked contrast to the law of mass action, in that the outcome is determined as much by the exact state of the system as it is by the strength of the input. In my view it is more representative of the real behaviour of complex systems. Hence it explains why the right input at the rightr time might vastly alter the course of direction of a disease, but is less likely to do so in the presence of a strong 'cosh', or in a system out of stability (acute emergency). It also explains why even the strongest 'cosh' might not have the desired effect, and can only be predicted on a statistical level across whole populations.

[Graham Lappin]

Yes it is, thanks for that. My earlier faceciousness was merely light-hearted, hope it came across that way.

However, this does raise the question of how much trust we place in the 'well-established' analgesic. It might have been documented for years as working, but the mechanism could still be placebo, as seems to be the case in the well-trained in the long-term sufferers.

How do we know that the observed brain changes are not purely due to the cognitive experience for the well-established drug too? Clearly that is what happens following the placebo.

So this is a very interesting experiment, but I'm not sure it penetrates the problem.

I think you misunderstand.
The trials with analgesics themselves may be run against a placebo but to be deemed efficacious they have to show a significant increase in effect (significant in the statistical sense). There is little doubt that codeine and it's derivatives and other drugs like tramadol etc are highly efficacious in relieving pain well above any placebo effect.

My original point was that the placebo effect can be shown to have a mechanistic aspect. The studies showing that placebo has a physiological effect are quite different from studies on the genuine medication.

[special_k]

Bunny, yes it's quite possible that I have misread something.

It may not be directly pertinent to the point of your initial post, but for what it's worth it does seem to be an insurmountable conundrum that placebos cannot be objectively calibrated, as it is not easy to separate the giving of a medicine, fake or real, from the awareness of doing so; especially with a medicine that can only possibly work because of that awareness.

The only way I can see is to calibrate them against a drug that is given without the knowledge of the subject, and that poses another dilema, namely ethics.

[Graham Lappin]

Bunny, yes it's quite possible that I have misread something.

It may not be directly pertinent to the point of your initial post, but for what it's worth it does seem to be an insurmountable conundrum that placebos cannot be objectively calibrated, as it is not easy to separate the giving of a medicine, fake or real, from the awareness of doing so; especially with a medicine that can only possibly work because of that awareness.

The only way I can see is to calibrate them against a drug that is given without the knowledge of the subject, and that poses another dilema, namely ethics.

I'm sorry but I have absolutely no idea what you are talking about.