New insights into placebo effect

New insights into placebo effect

(—Mathematical models developed by scientists at the University of Bristol are providing new insights into why the placebo effect exists and when it should occur. Their research is published today in the journal of Evolution and Human Behaviour.

A placebo – such as a sugar pill – is a treatment which is not effective through its direct action on the body but works because of its effect on the patient's beliefs.  But if individuals are capable of recovering without external aid, why do they rely on an external cue?  In other words, why have individuals not evolved the ability to get better immediately on their own?

Members of the Modelling Animal Decisions group in the University of Bristol's School of built mathematical models of the placebo effect which examine the trade-off between the costs and benefits of an when faced with a health problem.

The work is based on an idea proposed by the theoretical psychologist Professor Nicholas Humphrey.  He proposed that, as it can be beneficial to hold the immune system back from full operation due to uncertainties about the state of the world (such as the possibility of starvation), cues which indicate a change can therefore lead to an altered level of immune response.

The models take this argument even further and demonstrate that the placebo effect is modulated by the patient's expectations.  Previous studies measuring using (fMRI) provide which support the models, by showing between the placebo effect and regions of the brain associated with expectation.

The models show why changes to the perceived cost of getting well, the value of being well or external environmental factors can induce the placebo effect.

Dr Pete Trimmer, lead author of the work, said: "The placebo effect comes down to expectations about when to take action.  Waiting for a useless pill before taking action is not optimal.  But the general responsiveness to cues is adaptive, so it is logical for evolved organisms to display the placebo effect."

The models indicate that under stress it can be better for the immune system to work less effectively.  However, the most important finding of the research is that the particular type of belief in the treatment can lead to positive or negative effects.  The belief that a treatment will cure, without any need for the to do anything, could have deleterious effects on the patient's health.

Now that a theoretical approach has laid the foundations of understanding the placebo effect, future empirical work may provide insights as to how the placebo effect can be invoked and controlled in a clinical environment.  The Bristol study clearly shows that the focus of future placebo studies should be shifted to the type of belief patients have about their treatment rather than just whether a treatment is helpful or harmful.  A better understanding of the may change the code of practice for health practitioners and save human lives.

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Study evaluates placebo effectiveness

More information: 'Understanding the placebo effect from an evolutionary perspective' by Trimmer, PC, Marshall, JAR, Fromhage, L, McNamara, JM, Houston in Evolution and Human Behaviour.
Journal information: Evolution and Human Behaviour

Citation: New insights into placebo effect (2012, August 31) retrieved 18 September 2019 from
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Aug 31, 2012
How interesting to have an "evolutionary" explanation claim it is more beneficial to a body to allow itself to die of infection when it might be subjected to foor shortage.
In fact, diseases are penalties from God, which is why they are so specific. Lying brings heart disease; depraved contempt for others causes cancer; pettiness results in diabetes. And lack of faith in God produces clods and flu. Since all sin invlves lack of faith in God, that's why so many diseases begin with "cold and flu like symptoms". God allows substances to cure people, even in sin, since it can be difficult for them to concentrate if they're ill. This is a second chance. But it also suggests God would allow anything to act as a cure. Which can be the case, if all were honorable, all food contributing wholly to well being. Placebos are only a faint glimmer of this condition.

Sep 01, 2012
Holy crap, you aren't really this insane are you? I don't know whether to respond with logic, jokes, anecdotal evidence, ad hominem, or just useless sputtering.

I'll go with anecdotal for now since it's the easiest. I am an atheist and get sick less than anybody else I know. Not going to put serious effort into combating that amount of crazy.

Sep 01, 2012
(julianpenrod sounds like an internet troll rather than a Christian)

Sep 01, 2012
@julianpenrod. Your comment offends me deeply; my father died of complications from cancer, two friends from HIV, and a another with complications from diabetes. To ascribe illnesses to their 'sinning' is ignorant and cruel. Please don't bring your pre-renaissance perspectives to this 21st century discussion. Also, look up what the word 'fact' means.

Sep 01, 2012
Vulgarity and insults don't advance any conttradiction of what I say. They are, however, characteristic of those without any legitimate point to make. By the same token, the sleasy attempt to use p0olitics rather than proof, using the claim that what I say "offends" as reason not to say it! Just because someone is "offended" by a statement does not make that statement untrue! In fact, a look into the ailments so many, if not most or all, suffer will show that the illness is a punishment for their specific malefactions.

Sep 02, 2012
In fact, a look into the ailments so many, if not most or all, suffer will show that the illness is a punishment for their specific malefactions.

Especially all those bastard kids with leukemia. Totally had it coming.

Just because someone is "offended" by a statement does not make that statement untrue!

Hey, I agree whole heartedly with that part of your statement. People in general are offended too easily. That doesn't make the rest of your statements any less insane of course, but at least it's something.

Sep 02, 2012
Just because an action doesn't fall within your definition of "appropriate" doesn't mean it doesn't make sense.
So many question why children have certain diseases if diseases are a penalty. Among other things, consdier such eminent likelihoods that the ailments they suffer that weren't introduced by crooked doctors may be being overblown to convince parents to spend massively for "cures" that weren't needed. "Cures" that cause the damage ascribed to the "illness". And, to whatever extent the diseases may be genuine, consider that the child being sick may be the penance visited upon the parents, maybe for having killed several children beforehand.

Sep 02, 2012
whoops - looks like I took troll-bait. Check out julianpenrod's other physorg posts before deciding if their comments warrant your response. Spoiler alert: god and the new world order feature frequently, science rather less.

Sep 02, 2012
And, to whatever extent the diseases may be genuine, consider that the child being sick may be the penance visited upon the parents, maybe for having killed several children beforehand.

Who could possibly want to serve a God that would punish children with painful and deadly diseases due to something entirely outside of their control? If God is really like that then screw him, I want nothing to do with that nutjob.

Sep 02, 2012
Shabs42's statements notwithstanding, are we then to apply condemnatory terms to anyone who kills children regardless of their innocence? Such as those who authorize Predator drones to wipe out entire families to get one "terrorist" even though effective espionage methods, which haven't been tried since before September 11, could work just as well? Or nations that use white phosphorus on a calculated 300 to 1 attrition ratio against non combatant populations, even in cases where all that happened to their side was one of their own was kidnapped? Where was Shabs42 on those issues? What about the execution of criminals whose tissue types could provide useful transplants for children? And, don't forget, the parents who engaged in the unholy actions that bred the dire results are the cause of what is visited on their children.

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