Özüm Atasoy1, Melike Pekyürek1, Nilsu Çini1, Oytun Erbaş2,3

1Department of Radiation Oncology, Kartal Dr. Lütfi Kırdar Training and Research Hospital, Istanbul, Turkey
2Department of Physiology, Medical Faculty of Demiroğlu Bilim University, Istanbul, Turkey
3Institute of Experimental Medicine, Gebze-Kocaeli, Turkey

Keywords: Placebo, psychoneuroimmunology, nocebo


The placebo effect is a suggestion-based effect of a pharmacologically inert drug. Placebos have been in use since antiquity and its treatment power originate from the patient’s positive expectations about effect of the substance. Development of the placebo effect may be the result of either previous experiences which form conditioning mechanism or manipulations which form expectation mechanism. Placebos don’t produce solely beneficial results, but like other therapeutic agents they are also associated with adverse effects. The nocebo response is used to define these adverse effects and defined as a negative changes in symptoms and signs as a result of receiving inert substance or treatment. Both placebo and nocebo effects most likely have similar physiological mechanisms. The underlying neurological mechanism responsible for the development of the placebo effect is a well-studied topic. Changes in neurochemical pathways during the development of the placebo and nocebo responses have been documented by several studies. Psychoneuroimmunology is new field of scientific study and the evolution of placebo response through the psychoneuroimmunological pathways are under investigation.

Conflict of Interest

The authors declared no conflicts of interest with respect to the authorship and/or publication of this article.

Financial Disclosure

The authors received no financial support for the research and/or authorship of this article.