[whack]

With the first study, I notice that they didn't take into account the participants' general attitudes and happiness levels. It's possible that the people who "thought they were more active", felt that way because they were more optimistic/confident/happy in general, which in turn leads to the reduction in mortality.

The second study is more convincing, since it relies on randomly assigned groups. However, I don't think they measured the participants' actual level of activity during the course of the experiment? It's possible that the different interventions led to differences in activity level, during the experiment period, which led to the physiological improvements later seen.

Perhaps I'm being overly cynical in not accepting the study's conclusion. It just seems too fantastic, that someone can lose weight and reduce their mortality, merely by deluding themselves on how active they really are.

[buckminster]

It does seem fantastic, yet the placebo effect is a thing. Oddly enough, people have less trouble believing the opposite: that long term stress causes health problems, but stress is also just a state of mind, even if the stressors are real.

[Moodles]

I read recently that stress isn't actually related to mortality as much as people think. Similar to this post, it showed that people who are stressed, and additionally think that stress is bad for them, are more likely to die. Whereas people who felt stress and thought it was a good thing, i.e, their body calling them to action, were actually pretty much okay.

[whatshisface]

That sounds like people might be experiencing different things and calling it stress. For example one person might think stress and pressure are the same thing, and they would be physically healthy. Another person might only call themselves stressed when they started experiencing physical symptoms.

[rimliu]

I recently saw somewhere that placebo effect is not really a thing and is very overestimated. Sorry, have no source at hand.

[mortehu]

If a randomized controlled trial includes just two groups, one which gets a treatment and another which gets placebo, it cannot attribute any results to the placebo, because it's missing a control for the placebo, i.e. a group which gets no intervention at all. Many studies have made this error, but that doesn't mean there's never a placebo effect.

http://www.dcscience.net/2015/12/11/placebo-effects-are-weak...

[perl4ever]

I don't disagree exactly about missing a control for the placebo, but I think a control for a placebo is logically impossible, and therefore nobody has ever, or can ever, measured a placebo effect. Does that mean "there's never a placebo effect"? That's a philosophical question.

[dragonwriter]

> I don't disagree exactly about missing a control for the placebo, but I think a control for a placebo is logically impossible, and therefore nobody has ever, or can ever, measured a placebo effect.

The control for a placebo is no intervention, and not only has placebo effect been measured, but differential placebo effects by administration method have been measured (a placebo treatment that involves piercing the skin, for instance, has a bigger effect than a pill.) This is why a valid placebo needs to match administration method of the intervention being tested.

[perl4ever]

There is no way to coherently define the "placebo effect".

When you test a treatment vs. placebo, and speculate that there is a "placebo effect", it means that you are supposing that lying about treatment produces a therapeutic effect.

But you can't test a placebo vs. nothing, because a placebo is not a treatment, and nothing is not a placebo.

Giving a sugar pill and disclosing you are giving a sugar pill is not the same thing as lying about treatment (unless the recipient believes it is efficacious). Lying about it being efficacious doesn't help your experiment unless it's a credible lie.

Giving "nothing" cannot be a control because it is obviously different from a sugar pill. So you cannot do a blind test.

The idea of testing a placebo effect is an epistemological morass.

[collyw]

Couldn't you,

-Give people an effective drug tell them so.

-Give people a placebo tell them its a real drug.

-Give people a real drug tell them it may be placebo.

-Give them a placebo tell them it may be placebo.

It would certainly tell us something about the placebo.

[bcook]

You mention the word "tell" often, which makes me feel... uncertain.

I get your point but GP seems to understand uncertainty better.

You can't force me to believe.

[xapata]

That study wouldn't be checking placebo but whether the intervention beats placebo. Not sure why that's a mistake if measuring placebo is not a research goal.

[mortehu]

The mistake would be attributing any outcome to the placebo intervention. The mistake isn't in the construction of the experiment, but in the interpretation of its results.

[JamesBarney]

But a lot of reported placebo effects are more likely reversion to the mean.

[cryoshon]

the placebo effect is both larger and smaller than people intuitively assume.

it's larger in the sense that part of it is essentially impossible to control for; people in a clinical trial are predisposed to, at a minimum, think about the issue which is being investigated, which likely causes some sort of change in their mindset and subsequently their body. there's no real way to measure that adequately.

but it's smaller in the sense that the body isn't a system like in the Matrix where "the mind makes it real". if someone tells you that you drank lethal poison (but in actuality you drank a placebo), you might feel bad, but you won't die. the reverse is not necessarily true, bizarrely.

if you get a (unbeknownst to you) placebo/sham knee surgery as part of a trial to investigate the merit of a genuine surgical procedure designed explicitly to reduce pain, it'll reduce your pain almost as effectively as "the real deal". but here's the clincher. if you are told beforehand that it is a placebo, it'll still reduce your pain, although if i am remembering the study correctly it was a smaller benefit than those who were not told they received a placebo.

so if you know you're getting a placebo, the effect is WAY larger than it "should" be. but that's for a subjective variable -- pain. but when the subject isn't prompted about the effects of the placebo, or is administered a totally implausible placebo which can't possibly fix the issue -- like a pill to cure a severed arm -- it's even more impotent than we would expect.

[danieltillett]

I am not sure why you have been downvoted. Yes the placebo effect is often just a regression to the mean of a condition that varies. Imagine that you have a disease that goes up or down in serverity (say depression). People enter the trial when most ill and over the course of the trial they trend back to symptomatic mean (i.e. they get better on their own). This is why doctors favourite treatment "let's wait and see" is so effective.

[hshehehjdjdjd]

Yes, a hidden factor seems far more likely. There is probably some secondary variable that affects both your mortality rate and your perception of your own fitness. This seems much more likely, even to the point of seeming obvious.

[JamesBarney]

Healthy people feel healthy is probably a big confound.

[chiefalchemist]

Feel like it might be being optimistic. I believe "positive outlook" at the very least has correlated with better health, longevity, etc.

Feeling in better shape (and not actually being so) is a byproduct of optimism.

[usrusr]

"Being healthy makes people feel healthy" (and thus more optimistic/active/positive) would be the more occhamish interpretation of that correlation.

[chiefalchemist]

But I think it goes both way, with anticipation driving outcome as much as if not more than the other way around. That's the gist of the study. How you feel is more important than how healthy you actually are.

[kiliantics]

Stress has measurable physiological effects, e.g. cortisol levels

[agumonkey]

mindset is quite important: brain (para)sympathetic nervous system controls part of your heart rate, it's also linked to hormones (catecholamines IIRC) which in turn affects your vascular contractility and blood viscosity (then affecting many organs, eyes, lung, kidneys).

someone mostly happy may avoid a lot of stupid complications

[azhu]

Examined closely enough, optimism, confidence, and happiness are naught but delusion themselves. IMHO you are not being overly cynical in being skeptical, just do not discard these conclusions entirely. Weigh them amongst other studies. I suspect that the future will bring many more discoveries that approach health as a holistic relationship between mind and body. The brain is an organ like any other.

[whack]

> Examined closely enough, optimism, confidence, and happiness are naught but delusion themselves.

I agree completely. The base human emotions are all prone to delusion, but have substantial effects on the human body. "Unjustified" confidence and optimism can still have a great impact on physiological health. However, "perceived physical activity" is such a hyper-specific and abstract thought, that it doesn't engage our reptilian brain the same way something like "confidence" would. Hence why I find the study's conclusion pretty surprising.

[perl4ever]

I think that the belief that confidence and optimism improve health can cause extreme pain even when well intentioned.

An example from my experience is when an oncologist lies about a terminal cancer patient being in remission in the belief that a false confidence will cause them to last longer.

[jack9]

Emotions (and the feelings that combine to form attitudes) are delusions does not make sense. Physiological responses from an infant onward, are informed, but does not suppose a mental model that diverges from reality. The psychological assessment that we have multiple competing personalities that form our mental self inevitably leads to something that appears to be semi-random state. It's just internal physiological chaos manifest.

[memling]

Genuinely curious here: I created an account for this. How do you know that your delusion-sensing faculty is reliable, i.e., that it itself is not a delusion?