How come we've evolved to respond to placebo, then?

[quimcunx]

Yes but like I said earlier, if the body is able to mend itself without any chemical/physical intervention, why does this ability only kick in once the placebo is administered? If your body can do this without waiting for a placebo to come along, then surely you would have a greater chance of survival, than someone who does have to wait, for a placebo that may or may not appear.

Because if you believe in evolutionary theory cells mutate and some traits get passed on. 'responding to placebos' may not have a bit of gene to itself at all. It might be a side effect of something else or piggy back. Alternatively it might have been an evolutionary mutation that, because it was more successful than ''dies if ill'', it got passed on, despite being less successful than ''cures self without any help''.

Also you could have traits in an individual which:

cures illness A without medicinal intervention
cures illnes B with placebo
cures illness C only with appropriate medicine i.e. penicillin.

And many combinations of these.

 

[8ball]

I think you may be oversimplifying a bit.

Humans are a bit complicated.

Maybe if we could get some bacteria that respond to placebo we could test this properly . .

 

[quimcunx]

I think you may be oversimplifying a bit.

Humans are a bit complicated.

Maybe if we could get some bacteria that respond to placebo we could test this properly . .

It's my lunch hour. It's the internet.

You want to pay me to write a book?

 

[8ball]

G'wan then.

 

[quimcunx]

Again, I'd like to know which illnesses are succesfully cured by placebos and which not.

 

[Hocus Eye.]

'Quantum' is one of those 'alarm bell' words.

'Quantum' doesn't mean a lot. In fact a 'quantum leap' would be very small indeed.

I too have noticed how the existence of Quantum Physics being something scientific that few people understand, is used by mystically minded people to justify irrational beliefs as if there was a connection between the scientific method and that of their unproven so called 'spirit world'. They may delude themselves but not me.

 

[quimcunx]

G'wan then.

Done!


It's called ''The Selfish Gene'' and my name is Richard Dawkins.


You can buy it in all good bookshops.


Of you go.

 

[8ball]

Again, I'd like to know which illnesses are succesfully cured by placebos and which not.

Good for:

pain
subjective symptoms
autonomically-influenced stuff like high blood pressure

Useless for:

male pattern baldness
scurvy
maintaining a healthy glossy coat

Not an exhaustive list, obv.

 

[Hocus Eye.]

I think you may be oversimplifying a bit.

Humans are a bit complicated.

Maybe if we could get some bacteria that respond to placebo we could test this properly . .

I suppose that if anyone was ill with a bacteria and was successfully treated with a placebo, then it could be argued that the bacterium had responded to the placebo. Although the mechanism could be the auto-immune system being given extra stimulus from the brain.

It has often been suggested that some illnesses are psychosomatic i.e. caused by thoughts or brain activity. If illness can be so created then the reverse may be true and cures engendered in a similar way. Perhaps this is how the placebo effect operates.

 

[8ball]

I suppose that if anyone was ill with a bacteria and was successfully treated with a placebo, then it could be argued that the bacterium had responded to the placebo.

It has often been suggested that some illnesses are psychosomatic i.e. caused by thoughts or brain activity. If illness can be so created then the reverse may be true and cures engendered in a similar way. Perhaps this is how the placebo effect operates.

Some illnesses definitely are psychosomatic and the mind-body relationship is a pretty mysterious and poorly-understood thing (it seems to be really complicated). It is only one of several elements that comprise the placebo effect, though. In terms of it 'evolving', each element would have to be considered and I think it quite likely that they would have very different evolutionary roots.

Have to go and do worky things now . . .

 

[teuchter]

Some illnesses definitely are psychosomatic and the mind-body relationship is a pretty mysterious and poorly-understood thing (it seems to be really complicated). It is only one of several elements that comprise the placebo effect, though. In terms of it 'evolving', each element would have to be considered and I think it quite likely that they would have very different evolutionary roots.

Have to go and do worky things now . . .

It raises the question of whether psychosomatic illness has a "purpose" or is an unfortunate side effect of something else beneficial, or neither.

 

[quimcunx]

It raises the question of whether psychosomatic illness has a "purpose" or is an unfortunate side effect of something else beneficial, or neither.

Another good question.

*ponders*

 

[Hocus Eye.]

It raises the question of whether psychosomatic illness has a "purpose" or is an unfortunate side effect of something else beneficial, or neither.

How the hell can an any illness have a 'purpose'? When your car breaks down it doesn't have a 'purpose'. Teuchter the world your ideas live in doesn't seem to relate to the one most other people inhabit.

 

[quimcunx]

How the hell can an any illness have a 'purpose'? When your car breaks down it doesn't have a 'purpose'. Teuchter the world your ideas live in doesn't seem to relate to the one most other people inhabit.

Why not? Pain has a purpose. To alert us to something. psychosomatic symptoms might also serve a similar purpose.

 

[teuchter]

How the hell can an any illness have a 'purpose'? When your car breaks down it doesn't have a 'purpose'. Teuchter the world your ideas live in doesn't seem to relate to the one most other people inhabit.

Pain has a "purpose" in that it alerts you to damage to your body.

Vomiting has a "purpose" in that it expels toxins from your body quickly before they do to much damage.

 

[8ball]

Do you mean something simple like I know I need a day off when the stress causes me to come out in hives?

 

[Hocus Eye.]

Pain and vomiting are the body's reactions to the illness not the illness itself.

 

[quimcunx]

Pain and vomiting are the body's reactions to the illness not the illness itself.

And psychosomatic symptoms are most likely a reaction to something too.

 

[teuchter]

Nobody quite knows for sure why people get seasick.

But one interesting theory is that the sensory conflict caused (ie inner ears sense motion that doesn't match what the eyes see) is similar to what happens if a poison is affecting the nervous system, hence the reaction to vomit.

That would be an example of a response having a "purpose" but in the case of seasickness, the response being triggered by something that isn't actually dangerous.

 

[povmcdov]

We havent evolved to respond to placebos, we have evolved so that there is feedback from the central nervous system to the immune system and vice versa. It is this feedback that is thought to allow placebo effects to operate.

The body can fix itself, and not only in the presence of a placebo. Thats what your immune system does. The placebo effect is simply a modulatory effect on the immune system driven by the CNS/ANS/neuroendocrine systems. It isnt even nearly understood, but its not some mystical process.

One mechanism is through the "stress hormone" cortisol. Someone mentioned about stress being to stop you putting yourself in dangerous situations. Well, not really. To a neuroscientist stress is a specific phenomenon that is a bit different to the general usage of the word. It doesnt mean so much psychological stress, although that is part of it, but is more a general term for any deviation from the bodys normal internal state. In such states the bodys normal homeostatic mechanisms can cause damage by acting to counter the change.
A pertinant example is infection. Without regulation the immune system can become too active in fighting the infection causing unintended damage. To prevent this there is a system where messengers produced by immune activation (e.g. IL2) are detected in the paraventricular nucleus which starts a cascade of brain events culminating in the relase of cortisol from the adrenal glands. This Cortisol then damps down the immune response (hence why steroid drugs are used against autoimmune diseases - they are synthetic cortisol like drugs). There is clearly scope for higher level brain activity to influence the regulation of this system, and the neuroanatomy supports that idea.

From now on the science ends and its more like my hypothesis:
Lets say you have an infection, but in a survival situation. A lot of the nasty effects of being ill are caused by the immune response to infection, not infection itself. Things like a high temperature and inflammation could reduce your chances of survival in some situations, so cortisol can damp down the immune response until you are safer. It doesnt take much imagination to see how this sort of adaption could easily result in placebo effects.

 

[teuchter]

From now on the science ends and its more like my hypothesis:
Lets say you have an infection, but in a survival situation. A lot of the nasty effects of being ill are caused by the immune response to infection, not infection itself. Things like a high temperature and inflammation could reduce your chances of survival in some situations, so cortisol can damp down the immune response until you are safer. It doesnt take much imagination to see how this sort of adaption could easily result in placebo effects.

Do you mean the placebo effect could be the brain deciding you are now "safer", and stopping damping the immune response as you describe?

 

[povmcdov]

Yeah, something along those lines. More like placebo is a vestige of a system like I describe that has become modified as the brain evolved and higher level thinking became possible. It is likely that consious processes play little to no role in placebo effect though.
I think we've all heard of people who are under extreme stress then get ill afterwards. Maybe they were ill before stress levels fell, but the immune system was damped down. When the stressor is removed the immune system goes to work making them feel like crap.

 

[teuchter]

Well, it's an interesting suggestion. But I'm not sure how it would work for pain, which seems to be one of the main things that responds to placebo. I know that adrenaline can blank out pain to allow people to escape from dangerous situations etc., but then it suddenly will get worse once you're in safety. Rather than better.

 

[povmcdov]

Pain is the easier one to explain. Infection is a real process, pain is an enirely subjective, internally generated phenomenon. Its been known for decades that there are endogenous opioids that can damp down pain, and that certain brain areas such as the periaqueductal grey can modulate pain both at the brainstem level and effect pain gating at the spinal level. I dont know tha neuroanatomy of the PAG, but I expect there to be major connections to various limbic nuclei (the amygdala being the obvious one - fear can dull pain responses).

Dont think just in terms of hormones such as adrenaline, those links are global but slow. There are direct connections between brain areas that are just as important. I wasnt talking about the effects of adrenaline in any case, this is cortisol, a totally different hormone that just happens to be produced in the adrenal gland. Mineralocorticoid and some sex hormone production happen in the same organ. Its not just adrenaline.

 

[teuchter]

Dont think just in terms of hormones such as adrenaline, those links are global but slow. There are direct connections between brain areas that are just as important. I wasnt talking about the effects of adrenaline in any case, this is cortisol, a totally different hormone that just happens to be produced in the adrenal gland. Mineralocorticoid and some sex hormone production happen in the same organ. Its not just adrenaline.

Sure, but why would pain be damped after reaching safety? I can see why it would stop being damped until reaching safety, but after reaching safety (which is what I understand you are suggesting "taking a placebo" could represent), surely it should be turned on to make sure you do something about the injury or whatever is causing it.

I can see why your immune system might be turned back on, as it were, after reaching safety/taking a placebo. Although if this is the case, you would expect that taking a placebo would make you feel worse before getting better, which I don't think is the common experience.

 

[povmcdov]

Its not the same mechanism. The immune system is modulated by corticol and other hormones such as interleukins and cytokines, but pain is mediated by direct neural connections. Its easy to see how cortical brain areas responsible to higher functions could talk to the PAG which could then use its decending inhibitory connections to the spinal dorsal horns to modulate the subjective experience of pain.

Your original post refered to the immune system rather than pain. TBH I know much less about pain as a percieved phenomenon, more about the molecular biology of the receptors involved. Its not really my area, I'm a neuroscientist not a psychologist. I do know that the reason most placebo studies operate on pain sensitivity is that the experiments are easier to do, despite the fact that the results are less important. Getting someone to rate pain on a scale is easier (and cheaper) than measuring the response of the immune system to a challenge.

My main point is that we have not evolved to exhibit the placebo effect specifically, and that the placebo effect is not some sort of supernatural thing. It may not be understood fully yet, but we know about systems that could give rise it. I'm not saying anyone knows how it works, just that given the way that the brain talks to the immune system placebo effects are not that surprising.

If you are interested in the biology of this sort of thing then you should read about psychoneuroimunology and psychoneuroendocrinology. Its mostly postgrad level neurobiology though so isnt easy. There is a introductory text, "introduction to psychoneuroimmunology" by Daruna, but I'm not sure how good it is. Another good place is the journal "brain, behaviour and immunity" Its an elselvier journal so should be available free online through the science direct service.

Beware when reading stuff in the non-technical press that talks about psychosomatic illnesses and placebo effects - theres a lot of psuedoscientific guff bandied about.