The Emperor's New Drugs by Irving Kirsch

Author:Irving Kirsch
Language: eng
Format: epub
Publisher: Basic Books

Mind and Brain

One of the factors that determine the effectiveness of a placebo is the nature of the condition being treated. Conditions that have a strong psychological component - such as pain, anxiety and depression - are particularly prone to placebo influence, whereas conditions like bone fractures, diabetes and infertility are less likely to be affected by placebo treatment. But this does not mean that placebo effects are ‘all in the mind’. Placebos affect physiology as well as psychology.

The most common physiological effects of placebos are those that are associated with changes in subjective experience. When placebo stimulants make people feel energized and alert, for example, they also increase their blood pressure and heart rate, and when placebo tranquillizers relax people, they decrease their blood pressure and heart rate.32 Similarly, when Stewart Wolf gave ipecac to patients and told them it would ease their nausea, their reports of no longer feeling nauseous were accompanied by a resumption of normal gastric activity.

Many people seem particularly impressed by the physiological effects of placebos. They see them as evidence that the mind can affect the body. But the physiological placebo effects I have described are not all that surprising. Instead, they are exactly what we should expect, given what we know about the relation between mind and body. Strictly speaking, they are not really instances of mind affecting body. Rather, they are instances of body affecting body.33

What do I mean by this seemingly strange assertion? As far as we know, there is a physical substrate to all of our subjective experiences. In particular, experience seems to be linked to our brains. When the brain is injured, subjective experience is also changed, and the changes in experience are specific to the location of the tissue damage. Conversely, our subjective experiences are accompanied by changes in brain activity, and the particular areas of the brain in which these changes occur depend on the nature of the experience. With the advent of modern methods of imaging the brain, neuroscientists have located specific brain areas that are involved in vision, pain perception, speech, the voluntary control of movements and a vast myriad of other cognitive functions that were in the past attributed to the mind. Just as water is H2O, so the mind seems to be the brain.34

If what we experience is associated with something that happens in the brain, and if placebos change subjective experience, then we ought to be able to find changes in brain activity that are produced by placebos - and in fact this is precisely what has been found. A team of researchers led by Helen Mayberg, a neurologist at Emory University and the University of Toronto, have used a technique called positron emission topography (PET) to study changes in brain activity associated with the experience of depression.35

In the first of these studies, the researchers identified the areas of the brain that are associated with normal sadness. They asked volunteer subjects to think about some very sad personal experiences - and about some emotionally neutral experiences - while their brains were being imaged in a PET scanner.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.