Doctor’s cannot prescribe placebos as it is considered unethical to prescribe an inactive compound. As you say, we often will give innocuous medications or change to another drug in the same class if the first one doesn’t work which is getting close to placebo.

And anyone who thinks benzos only work as well as placebo has never met a patient with anxiety disorder. Short-term use is very effective, long-term is not.

Alan

There was a great article on the Placebo Effect at Skeptic Magazine here which answers your questions.

http://www.skeptic.com/eskeptic/09-05-20#feature

the system is too risk-averse; it takes way too long for important drugs to be approved

Perhaps so, but that is no reason for a drug to get approved if its sponsor is willing to defraud the FDA and denied it if its sponsor is unwilling.

You can understand why big-pharmaceutical industries would be interested in studying the placebo effect. In order to fabricate good medicines, the effects have to be real… in the sense that the healing effects are not simply due to psychological…

But maybe pain is higher up the chain of command. Damage control reports are fused with an appreciation of the tactical situation to produce pain that modulates behaviour in the obvious way without being impossible to over-ride if the strategic situation demands it. So after a hit on Alpha Turret the Alpha-Turret-Fire light comes on. Another hit starts a fire close to the magazine. Then the Alpha-Turret-Fire light goes out; Alpha Turret is still on fire but the tactical situation demands that damage control crews go to fight the fire threatening the magazine. Perhaps the captain will over-rule this, unless the forward turret can be brought back into action the approaching enemy torpedo boat will sink the ship anyway.

Scuttling the nautical metaphor and returning to the body, pain has an obvious role of modulating behaviour so as to rest an injury and then to gradually bring the affected limb back into use as it heals. Suppose that pain is integrating both the degree of damage and an instinctive estimate of how much rest is a good trade-off between healing and being out of action. Perhaps the instinctive estimate is sophisticated enough to pick up on the idea that the magic medical pill will take care of the healing, so rest is no longer required and activity need not be discouraged. Result: pain relief.

Perhaps placebo effects are sensitive the fine distinction of whether the patient thinks of a pill as paliative or curative. Since it is probably the patients subconscious beliefs that matter to the bodies pain system, this is probably hard to research.

I agree with Ben A’s points. Anxiety, depression, and chronic pain are notable for their degree of placebo responsiveness, as I recall. And that probably goes a long way towards explaining why a diazepam trial could fail to beat placebo.

Variable sensitivity is probably an issue here too, and leads to a lower trial dose. If you hit a set of anxious people with an “elephant dose” of diazepam, they would probably all respond very strongly indeed – but such a dose wouldn’t be appropriate for everyone (would put some to sleep), and wouldn’t be used in the trial.

Perhaps chronic effectiveness is also a problem. The acute efficacy is certainly high but if someone did a trial of chronic use (over a month) it might be hazier due to tolerance.