Haour France
Inserm-EMI 350, Hôpital Saint-Antoine, 184, rue du Faubourg Saint-Antoine, 75571 Paris Cedex 12, France.
Med Sci (Paris). 2005 Mar;21(3):315-9. doi: 10.1051/medsci/2005213315.
A placebo is a sham treatment such as pill, liquid, injection, devoid of biological activity and used in pharmacology as a control for the activity of a drug. In many cases, this placebo induces biological or psychological effects in the human. Two theories have been proposed to explain the placebo effect: the conditioning theory which states that the placebo effect is a conditioned response, and the mentalistic theory for which the patient expectation is the primary basis of the placebo effect. The mechanisms involved in these processes are beginning to be understood through new techniques of investigation in neuroscience. Dopamine and endorphins have been clearly involved as mediators of the placebo effect. Brain imaging has demonstrated that the placebo effect activates the brain similarly as the active drug and in the same brain area. This is the case for a dopamine placebo in the Parkinson'disease, for analgesic-caffeine- or antidepressor-placebo in the healthy subject. It remains to be understood how conditioning and expectancy are able to activate, in the brain, memory loops that reproduce the expected biological response.
安慰剂是一种虚假治疗手段，如药丸、液体、注射剂等，不具备生物活性，在药理学中用作药物活性的对照。在许多情况下，这种安慰剂会在人体中引发生物学或心理学效应。人们提出了两种理论来解释安慰剂效应：条件反射理论，该理论认为安慰剂效应是一种条件反应；以及心理主义理论，该理论认为患者的期望是安慰剂效应的主要基础。通过神经科学的新研究技术，这些过程中涉及的机制正开始被人们所理解。多巴胺和内啡肽已被明确作为安慰剂效应的介质。脑成像显示，安慰剂效应与活性药物类似地激活大脑，且激活的是相同的脑区。帕金森病中的多巴胺安慰剂、健康受试者中的止痛咖啡因安慰剂或抗抑郁安慰剂都是如此。条件反射和期望如何能够在大脑中激活重现预期生物学反应的记忆回路，仍有待进一步了解。
