Nocebo effect as the opposite of the placebo effect: Systematic review

Abstract

Background: the placebo effect refers to a clinical improvement in a patient as a result of interactions with the treating physician, information received about the treatment, and the defined therapy. The placebo effect is a broad field involving complex neurobiological and neurotransmitter mechanisms, and recent studies have provided evidence that these effects are genuine biopsychosocial phenomena. Although placebos cannot cure a disease, they can provide relief to the patient and improve the effectiveness of pharmaceuticals. The effectiveness of placebos depends on several factors, including the patient's age, psychological and emotional state, the doctor's approach, and the information provided to the patient. The nocebo effect, which generates an adverse response to this type of treatment, which can be defined as the effect opposed to placebo. 
Method: an exhaustive search was carried out in PubMED and a synthesis of the available evidence on the neurobiological factors associated with the nocebo effect. For this, a systematic review was carried out. 
Results: after manual selection, 4 articles were reviewed for the preparation of results.
Conclusion: therapeutic interaction, facial expressions, and eye contact influence placebo analgesia. The patient's expectation, based on the physician's information and nonverbal cues, is crucial in the placebo response. Variables such as age and psycho-emotional state reduce the efficacy of the placebo. The nocebo effect causes adverse responses related to negative expectations. The presentation of medical information influences the nocebo response. Cognitive behavioral treatments and medications can reduce nocebo effects. These determinations have implications for the treatment of psychiatric conditions and medication management