Fabrizio Benedetti
Neuroscience Dept, University of Turin Medical School and National Institute of Neuroscience, Turin, Italy
Objectives: The placebo effect has evolved from being thought of as a nuisance in clinical and pharmacological research to a biological phenomenon worthy of scientific investigation in its own right. The study of the placebo effect and of its negative counterpart, the nocebo effect, is basically the study of the psychosocial context around the treatment and the patient, and it plays a crucial role in the therapeutic outcome [1,2].
Methods: In recent years, different types of placebo effects have been analyzed with sophisticated biological tools, such as neuropharmacology, neuroimaging, and single-neuron recording from awake subjects, that have uncovered specific mechanisms at the anatomical, physiological, biochemical and cellular level.
Results: Most of our knowledge about the neurobiological mechanisms of the placebo effect comes from the field of pain, whereby different neurotransmitters have been found to be involved, such as endogenous opioids and endocannabinoids in placebo analgesia [3] and cholecystokinin in nocebo hyperalgesia [4]. In addition, dopamine has been found to play a role as well, with an activation of dopamine receptors in the nucleus accumbens in placebo analgesia and their de-activation in nocebo hyperalgesia. Recent findings suggest that some of these mechanisms are also present in other medical conditions, like Parkinson’s disease, in which placebos induce dopamine release in the striatum and changes of neuronal activity in the thalamus, subthalamus and substantia nigra [5].
Conclusions: This recent research has revealed that these placebo-induced biochemical and cellular changes in a patient’s brain and body are very similar to the biochemical changes induced by drugs. This new way of thinking may have profound implications both for clinical trials and for medical practice [6].
References
[1] Colloca L, Benedetti F (2005) Nature Rev Neurosci 6: 545-552.
[2] Finniss DG, Miller F, Kaptchuk T, Benedetti F (2010) Lancet 375: 686-695.
[3] Benedetti F, Amanzio M, Rosato R, Blanchard C (2011) Nature Med 17: 1228-1230.
[4] Benedetti F, Amanzio M, Maggi G (1995) Lancet 346: 1231.
[5] Benedetti F, Colloca L., Torre E, Lanotte M, et al. (2004) Nature Neurosci 7: 587-588.
[6] Colloca L, Lopiano L, Lanotte M, Benedetti F (2004) Lancet Neurol 3: 679-684.
Reference: PAGE 21 () Abstr 2635 [www.page-meeting.org/?abstract=2635]
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