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Medical The Placebo Effect - What's your theory

  1. Feb 14, 2007 #1
    This is something strange that has baffeled scientist. Several times a day, for several days, you induce pain in someone. You control the pain with morphine until the final day of the experiment, when you replace the morphine with saline solution. Guess what? The saline takes the pain away.

    This is the placebo effect: somehow, sometimes, a whole lot of nothing can be very powerful. Except it's not quite nothing. When Fabrizio Benedetti of the University of Turin in Italy carried out the above experiment, he added a final twist by adding naloxone, a drug that blocks the effects of morphine, to the saline. The shocking result? The pain-relieving power of saline solution disappeared.

    So what is going on? Doctors have known about the placebo effect for decades, and the naloxone result seems to show that the placebo effect is somehow biochemical. But apart from that, we simply don't know.
    Benedetti has since shown that a saline placebo can also reduce tremors and muscle stiffness in people with Parkinson's disease (Nature Neuroscience, vol 7, p 587). He and his team measured the activity of neurons in the patients' brains as they administered the saline. They found that individual neurons in the subthalamic nucleus (a common target for surgical attempts to relieve Parkinson's symptoms) began to fire less often when the saline was given, and with fewer "bursts" of firing - another feature associated with Parkinson's.

    The neuron activity decreased at the same time as the symptoms improved: the saline was definitely doing something. We have a lot to learn about what is happening here, Benedetti says, but one thing is clear: the mind can affect the body's biochemistry. "The relationship between expectation and therapeutic outcome is a wonderful model to understand mind-body interaction," he says. Researchers now need to identify when and where placebo works. There may be diseases in which it has no effect. There may be a common mechanism in different illnesses. As yet, we just don't know.
  2. jcsd
  3. Feb 14, 2007 #2
    You have endogenous opioids that are natural pain killers involved in the placebo effect...

    And so if you inject an opioid blocker (naloxone) you no longer have an effect of placebo...

    What is interesting is the number of 'side effects' that people complain about with placebo...

    And yes you are correct... Your mind can control physiological responces to pain... For example, many soldiers in the war have such horrific injuries but carry on fighting and don't feel the pain... Adrenaline?... Or is it that they have so many other stimuli that the can't think about it?... Probably a combination of both...

    You've raised a lot of interesting questions though...
  4. Feb 14, 2007 #3


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    Do you have a citation for that study? It will help for others to discuss it if they know where the full details are reported.

    Here's the full citation on that one (again, helpful if we're going to discuss papers to provide the full citation so others can easily locate it).
    Benedetti F, Colloca L, Torre E, Lanotte M, Melcarne A, Pesare M, Bergamasco B, Lopiano L. Placebo-responsive Parkinson patients show decreased activity in single neurons of subthalamic nucleus Nature Neuroscience 7, 587 - 588 (2004)
  5. Feb 15, 2007 #4
    What do you mean citation? I'm sorry im new to this stuff.
  6. Feb 15, 2007 #5


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    The reference for the study you pulled that information from.
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