Placebo effects

The current evidence suggests that there might be some beneficial effects on postmenopausal symptoms, but it is not possible to be more categorical at present given the conflicting observations in the limited number of studies undertaken and the possibility that placebo effect may explain the changes noted in the incidence of subjective symptoms. 

The identification of a placebo effect is not easy and its study is full of drawbacks and pitfalls. In fact, the effect which follows the administration of a placebo can be due... 

When all these phenomena are tuled out and the correct methodological approach is used, striking placebo effects can be detected which are mediated by psychophysiological mechanisms worthy of scientific inquiry [4, 5]. Therefore, it is this psychological component that represents the real placebo effect. 

The neural mechanisms underlying the placebo effect are only partially understood and most of our knowledge comes from pain, although recently Parkinson s disease, immune and endocrine responses, and depression have emerged as interesting models (Fig. 1). In each of these... 

The nocebo effect, or response, is a placebo effect in the opposite direction. For example, administration of an inert substance along with verbal suggestions of pain... 

Benedetti F, Mayberg HS, Wager TD et al (2005) Neurobiological mechanisms of the placebo effect. J Neurosci 25 10390-10402... 

Placebo Effect Placebo Response Placenta Growth Factor... 

Clinical trials should be designed so as to mirtimise potential sources of bias. It is known that patients can demonstrate a positive response to treatments that they believe will benefit them, even if no pharmaceutical agent has been admrrtistered (the placebo effect ). Similarly, investigators may be biased in their observations by an expectation of particular results. To avoid such bias, blinded trial designs are used. 

For some conditions, a large placebo effect can be anticipated. For example, studies of hormone replacement therapies for hot flashes in postmenopausal women consistently show a 50% decline from baseline in the number of daily hot flashes in the placebo group. Therefore, in order to show significance, an active treatment must produce an effect that is substantially larger than 50%. A marked placebo response is commonly observed with any condition that has a subjective component, such as chronic pain (e.g. arthritis), episodic pain (e.g. headaches), psychological states (e.g. anxiety), and certain physiologic measurements (e.g. blood pressure). 

Swartzman, L. C. 8c Burkell, J. (1998). Expectations and the placebo effect in clinical drug trials why we should not turn a blind eye to unblinding, and other cautionary notes. Clin. Pharmacol. Ther., 64, 1-7. 

It was with that in mind that one of my postgraduate students, Guy Sapirstein, and I set out to investigate the placebo effect in depression - an investigation that I describe in the first chapter of this book, and that produced the first of a series of surprises that transformed my views about antidepressants and their role in the treatment of depression.4 In this book I invite you to share this journey in which I moved from acceptance to dissent, and finally to a thorough rejection of the conventional view of antidepressants. 

The conventional view of depression is that it is caused by a chemical imbalance in the brain. The basis for this idea was the belief that antidepressant drugs were effective treatments. Our analyses showing that most - if not all - of the effects of these medications are really placebo effects challenges this widespread view of depression. In Chapter 41 examine the chemical-imbalance theory. You may be surprised to leam that it is actually a rather controversial theory and that there is not much scientific evidence to support it. While writing this chapter I came to an even stronger conclusion. It is not just that there is not much supportive evidence rather, there is a ton of data indicating that the chem-... 

The chemical effect of antidepressant drugs may be small or even non-existent, but these medications do produce a powerful placebo effect. In Chapters 5 and 6 1 examine the placebo effect itself. 1 look at the myriad of effects that placebos have been shown to have and explore the theories of how these effects are produced. 1 explain how placebos are able to produce substantial relief from depression, almost as much as that produced by medication, and the implications that this has for the treatment of depression. 

In 1995 Guy Sapirstein and I set out to assess the placebo effect in the treatment of depression. Instead of doing a brand-new study, we decided to pool the results of previous studies in which placebos had been used to treat depression and analyse them together. What we did is called a meta-analysis, and it is a common technique for making sense of the data when a large number of studies have been done to answer a particular question. It was once considered somewhat controversial, but meta-analyses are now common features in all of the leading medical journals. Indeed, it is hard to see how one could interpret the results of large numbers of studies without the aid of a meta-analysis. 

But people recover from colds even if you give them nothing at all. So when the patients in our imaginary study took a dummy pill and their colds got better, the improvement may have had nothing to do with the placebo effect. It might simply have been due to the passage of time and the fact that colds are short-lasting illnesses. 

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