BBC's Horizon covered the Placebo Effect last week and folks in UK can see here: http://www.bbc.co.uk/iplayer/episode/b03wcchn/Horizon_201320...
Came on here to say the same thing... Youtube mirror here: http://www.youtube.com/watch?v=oKG1lgI4zIk
Even Knowingly Taking A Placebo Seems To Help (2010)
11–20 of 33 posts
Re: Even Knowingly Taking A Placebo Seems To Help (2010)
#12This is quite an old paper, and I actually wrote a blog post about it (back when I had a blog). However, my issue with this study is that there was no deceptive placebo condition (i.e. what normally happens). I actually attempted to replicate this finding and didn't find any effect when a deceptive condition was involved, suggesting that IBS may be a special case. Interestingly enough, IBS patients have been found to…
I have definitely experienced the coffee and pain killer placebo more often than not.
Thinking about it now, it make sense that once you ingest either to alleviate certain symptoms, you let go of a portion of directed anxiety/overt attention in expectation of relief thereafter.
Despite knowing the placebo pill beforehand, I'd hazard a guess that the same brain areas associated with non-placebo oral administration will light up with activity in an MRI scan.
Anyone know if there is any scientific literature on this phenomenon?
Re: Even Knowingly Taking A Placebo Seems To Help (2010)
#13*makes sense
Re: Even Knowingly Taking A Placebo Seems To Help (2010)
#14The Placebo Effect is something of a misnomer, as there are actually many different placebo effects, which bias trial data in subtle and interesting ways. Effects like regression to the mean and the natural history of the disease, for example, will result in objective changes to a patient's condition even in cases where the patient is acutely aware they are only taking a placebo. Analyses comparing placebo interventi…
Suppose that by "placebo effect", we really are identifying a marker for something like "experimenter effect" or "physician effect" and only on subjective end-points.
I believe it would still be correct, and of practical value, to say that the placebo effect is real. Prescribing someone a placebo results in them receiving the experimenter/physician effect - they subjectively report feeling better - that's a good thing.
Re: Even Knowingly Taking A Placebo Seems To Help (2010)
#15The Placebo Effect is something of a misnomer, as there are actually many different placebo effects, which bias trial data in subtle and interesting ways. Effects like regression to the mean and the natural history of the disease, for example, will result in objective changes to a patient's condition even in cases where the patient is acutely aware they are only taking a placebo. Analyses comparing placebo interventi…
OK, lets take this in order. Hrobjarrtsson and Goetzche's review actually undermines your point around there being many placebo effects (which is the approach taken by Benedetti), as they modelled wildly different clinical trials (the inclusion criteria were simply possessing both a placebo and no-treatment arm).
Furthermore, Meissner et al 2007 re-analysed those studies and found large effects where the outcome could be mediated by nervous system, and very low effects where there was no direct nervous system link.
Additionally, uncertain expectations (you may receive a drug) are given in clinical trials and Vase (2002) found that placebo effect sizes were much smaller in this context than they are when placebos are deceptively administered (this is a potent painkiller) (as they normally are in clinical practice and experimental research) (c.f. Kirsch & Wiexel 1998, Amanzio et al 2001). Also certain vs uncertain expectations are associated with differential amounts of dopamine release, which has been associated with response to placebo (Scott et al 2007, DeLa Fuente-Fernandez, 2002, 2004).
I agree with many of your comments around this paper, and essentially it was only published because Kaptchuk and Kirsch are two of the leading names in the non-clinical field.
And the papers from 2010, and has been getting this treatment for a while....
Re: Even Knowingly Taking A Placebo Seems To Help (2010)
#16This is quite an old paper, and I actually wrote a blog post about it (back when I had a blog). However, my issue with this study is that there was no deceptive placebo condition (i.e. what normally happens). I actually attempted to replicate this finding and didn't find any effect when a deceptive condition was involved, suggesting that IBS may be a special case. Interestingly enough, IBS patients have been found to…
I have definitely experienced the coffee and pain killer placebo more often than not. Thinking about it now, it make sense that once you ingest either to alleviate certain symptoms, you let go of a portion of directed anxiety/overt attention in expectation of relief thereafter. Despite knowing the placebo pill beforehand, I'd hazard a guess that the same brain areas associated with non-placebo oral administration wil…
For the placebo effects of coffee - Kirsch & Wiexel 1988 (can't find it online, annoyingly enough).
There probably are some fMRI studies, but I really don't trust most of those due to the difficulties in avoiding multiple comparisions (see Vul et al 2009, Voodoo Neuroscience).
Re: Even Knowingly Taking A Placebo Seems To Help (2010)
#17The Placebo Effect is something of a misnomer, as there are actually many different placebo effects, which bias trial data in subtle and interesting ways. Effects like regression to the mean and the natural history of the disease, for example, will result in objective changes to a patient's condition even in cases where the patient is acutely aware they are only taking a placebo. Analyses comparing placebo interventi…
OK, lets take this in order. Hrobjarrtsson and Goetzche's review actually undermines your point around there being many placebo effects (which is the approach taken by Benedetti), as they modelled wildly different clinical trials (the inclusion criteria were simply possessing both a placebo and no-treatment arm). Furthermore, Meissner et al 2007 re-analysed those studies and found large effects where the outcome coul…
Indeed, all fair points.
Though I disagree that Hróbjartsson et al undermines the notion of many placebo effects.. or maybe I don't, depending on our definition of placebo effect.
If we define "placebo effect" as any clinically significant change observed in the placebo wing of a clinical trial, there are many placebo effects. As I mentioned before, regression to the mean, natural history of the disease, experimenter effect, and so on.
Alternatively, we could define it as any clinically significant change observed in the placebo wing of a clinical trial which is not also observed in a no treatment wing. This would eliminate things like regression to the mean and arguably leave behind only a "true" placebo effect. Though even here, we have to account for bias (and perhaps even classical conditioning?) I wonder how much placebo effect is left if these are controlled for?
Within the context of analysing trial data, it is the former definition we are interested in. But within the context of discussing "the placebo effect" as a standalone phenomenon, I'd argue the latter definition is more useful.
Unfortunately, as most trials don't have no treatment arms, any clinically significant changes observed in the placebo arm are chalked up to "the placebo effect", especially by the media (though sometimes by clinicians), even when there is good reason to think many of those same changes would have been observed under no treatment. Which IMHO leads to a distorted view of the clinical relevance of the placebo effect outside the context of a clinical trial. Especially as the placebo effect appears to have a reputation as a bizarre mind-over-matter affair.
Re: Even Knowingly Taking A Placebo Seems To Help (2010)
#18Earlier quoted context omitted.
OK, lets take this in order. Hrobjarrtsson and Goetzche's review actually undermines your point around there being many placebo effects (which is the approach taken by Benedetti), as they modelled wildly different clinical trials (the inclusion criteria were simply possessing both a placebo and no-treatment arm). Furthermore, Meissner et al 2007 re-analysed those studies and found large effects where the outcome coul…
Indeed, all fair points. Though I disagree that Hróbjartsson et al undermines the notion of many placebo effects.. or maybe I don't, depending on our definition of placebo effect. If we define "placebo effect" as any clinically significant change observed in the placebo wing of a clinical trial, there are many placebo effects. As I mentioned before, regression to the mean, natural history of the disease, experimenter…
Ah, I see what the issue is here. I typically (used to) work in experimental placebo research, rather than clinical placebo research (I'm a psychologist by trade) so I would be more interested in those studies, rather than clinical trials.
In terms of what's left over after accounting for no treatment, Vase and H&G got into a big academic fight about this, and it appears that the effect size for placebo effects in pain is approximately (d=0.5), which is a relatively large effect (especially within psychology). This doesn't entirely account for experimenter effects, though with the use of a balanced-placebo design, those can be accounted for.
In terms of clinical trials, I would tend to agree with your second definition. Its not perfect, but its as good as it tends to get.
I think that one of the issues with placebo research is this notion of mind-over-matter, in that such a viewpoint is the reason that it is perceived as special, and also a reason why people disbelieve in it.
Based on old research (Levine, 1979) many (but not all) placebo effects in pain appear to be mediated by endogenous opioids,which I would take to mean that they are pretty naturally mediated by the brain, and so its a physical phenomenon. Many people do go a bit crazy with the woo around it though, I do agree.
Funny that this came up today, when I'm currently finalising a hopefully final draft of my thesis on the placebo (PROTIP: never, ever leave your university before submitting a PhD, it tends to go badly).
Re: Even Knowingly Taking A Placebo Seems To Help (2010)
#19The Placebo Effect is something of a misnomer, as there are actually many different placebo effects, which bias trial data in subtle and interesting ways. Effects like regression to the mean and the natural history of the disease, for example, will result in objective changes to a patient's condition even in cases where the patient is acutely aware they are only taking a placebo. Analyses comparing placebo interventi…
Suppose that by "placebo effect", we really are identifying a marker for something like "experimenter effect" or "physician effect" and only on subjective end-points. I believe it would still be correct, and of practical value, to say that the placebo effect is real. Prescribing someone a placebo results in them receiving the experimenter/physician effect - they subjectively report feeling better - that's a good thin…
The problem with "they subjectively report feeling better" is that sometimes the people "lie" voluntary or involuntary. Perhaps they don't feel better but want to make the experimenter happy. Perhaps they don't feel better but wish to feel better. Too much possible sources of confusion.
Just using an exaggeration for comparison, if you pay $1000000 to the experiment subject in one arm to say that they fell better, then you will get a very big improvement, but it doesn't mean that they really feel better. This is an exaggeration, but the problem is that there are a lot of more subtle things that can change the self reported feeling.
I don't know how to measure the well feeling in a non subjective way. If I may just made up an inexistent medical device, perhaps I can put a 24hs endorphin measurer to the test subject and look for a difference in the mean concentration.
Re: Even Knowingly Taking A Placebo Seems To Help (2010)
#20Here's a clever guess at why this might be true from an economics perspective (I'm not the author): http://cheaptalk.org/2010/08/10/blogging-something-i-know-no...
A clever response titled: "Blogging Something I Know Nothing About."