If the placebo effect is real, what might the mechanism be? We can’t just write it off as delusions of hyper-suggestible patients. There’s evidence that several things might be going on. The main hypotheses are: expectancy, motivation, conditioning, and endogenous opiates.
Expectancy is an established psychological phenomenon. It even affects vision: we are more likely to see what we expect to see. Wine tastes better if the price is higher. Kids like fast food better if it comes in a McDonald’s wrapper. If we expect to feel pain we are more likely to feel pain. If we are told to expect a strong painkiller, we’re more likely to get pain relief.
Motivation, the need or desire to improve health or get relief, has been shown to contribute independently to the placebo response. Patients who are strongly motivated to get well are more compliant and follow health advice more conscientiously. And patients who are more compliant about taking their placebo pills regularly get a stronger placebo response.
Conditioning is what Pavlov did to his dogs. People learn to associate pills and medical treatments with relief of symptoms. The body even learns physiologic responses: dogs salivate when injected with morphine; after they become conditioned, injecting a placebo makes them salivate, although not as much.
Endogenous opiates are pain-relieving chemicals produced in the brain that mimic the effects of opium-like drugs (morphine, etc.). There is some evidence that when patients respond to placebos, their brains produce more of these chemicals. Imaging studies have shown activation of opioid receptors in the brain when people are told that a placebo is a painkiller. And there is evidence that giving a drug that blocks the effect of narcotics can also block the placebo effect.
Dopamine levels increased in the brains of Parkinson’s patients after taking a placebo; and patients who said they felt better released higher levels of dopamine. In another brain imaging study, researchers had patients play a game and estimate their chances of winning. The same reward areas in the brain lit up in subjects who thought they would win as in patients who were most convinced that the placebo painkiller would work. Another study of patients who preferred either Coca Cola or Pepsi found that brand information was processed in a different part of the brain than taste from blind taste tests. We may be seeing clues about how the brain handles anticipation, expectation, optimism, previous experience, or who knows what. There may be genetic differences or differences in dopamine receptor responsiveness. Brain imaging is a blunt tool, and it’s too soon to know what these studies mean, but it’s a promising avenue of research. genetic differences or differences in dopamine receptor responsiveness. Brain imaging is a blunt tool, and it’s too soon to know what these studies mean, but it’s a promising avenue of research.
NLP & Placebo’s; How Could They Work?
If the placebo effect is real, what might the mechanism be? We can’t just write it off as delusions of hyper-suggestible patients. There’s evidence that several things might be going on. The main hypotheses are: expectancy, motivation, conditioning, and endogenous opiates.
Dopamine levels increased in the brains of Parkinson’s patients after taking a placebo; and patients who said they felt better released higher levels of dopamine. In another brain imaging study, researchers had patients play a game and estimate their chances of winning. The same reward areas in the brain lit up in subjects who thought they would win as in patients who were most convinced that the placebo painkiller would work. Another study of patients who preferred either Coca Cola or Pepsi found that brand information was processed in a different part of the brain than taste from blind taste tests. We may be seeing clues about how the brain handles anticipation, expectation, optimism, previous experience, or who knows what. There may be genetic differences or differences in dopamine receptor responsiveness. Brain imaging is a blunt tool, and it’s too soon to know what these studies mean, but it’s a promising avenue of research. genetic differences or differences in dopamine receptor responsiveness. Brain imaging is a blunt tool, and it’s too soon to know what these studies mean, but it’s a promising avenue of research.
Thoughts?