Placebo Theory and Its Implications for Research and Clinical Practice: A Review of the Recent Literature

Abstract

Although placebo effect is a common phenomenon in medicine and research, its mechanisms are not well understood. With the advent of modern medicine, placebo became a symbol for an outdated, morally questionable practice implying deceit and paternalism. However, in recent years, there has been an increasing amount of rigorous research into the mechanisms of placebo response and placebo analgesia with most studies coming from the field of pain medicine. New theories on placebo mechanisms have shown that placebo represents the psychosocial aspect of every treatment and the study of placebo is essentially the study of psychosocial context that surrounds the patient. Therefore, its understanding is essential for researchers and all medical practitioners, particularly those dealing with patients suffering from pain, depression, and motor disorders. In this article, we review the theories on placebo mechanisms and discuss their implications for clinical practice and the design of clinical trials.

The effectiveness of pulsed electrical stimulation in the management of osteoarthritis of the knee: Results of a double‐blind, randomized, placebo‐controlled, repeated‐measures trial

“…A number of characteristics of our study have previously been noted to contribute to a robust placebo response (35,(37)(38)(39). Blinding was apparent throughout, and the level of commitment required to participate was considerable and over an extended period of time.…”

‘Placebos’ and the logic of placebo comparison

“…The surprising result -which the meaning-theories help us appreciate -is that the range of aspects which can have a therapeutic effect is both large and in many cases unintuitive. So for example: the mere number of pills (Blackwell et al 1972;de Craen et al 1999;Moerman 2000), the branding of pills (Branthwaite and Cooper 1981), whether one is given a pill or an injection (Amanzio et al 2001), and the justified belief that one has undergone surgery (Cobb et al 1959;Dimond et al 1960), are just some examples of the different aspects of treatments that have been shown to have therapeutic consequences (See for more references: Koshi and Short 2007;Price et al 2008;StewartWilliams and Podd 2004). That is to say, more pills are better than fewer, branded pills are better than unbranded, injections work better than pills, and the justified belief that one has undergone surgery is itself sufficient for patients to improve.…”

Efeito de exercícios motores orofaciais e laserterapia nos sintomas de desordem temporomandibular e funções orofaciais

“…O efeito placebo é inerente em todo contato clínico-paciente (George e Robinson, 2010), principalmente aqueles que lidam com pacientes que sofrem de condições como dor crônica, depressão e comprometimento da função motora (Koshi et al, 2007). O contato repetido no tratamento, provavelmente, funciona como um processo de condicionamento no estabelecimento e manutenção do placebo.…”

“…Assim, um tratamento placebo (não ativo) não deve ser considerado ausência de tratamento, mas sim ausência de um tratamento específico (ativo) (Koshi et al, 2007), pois ele produz uma resposta terapêutica por uma consequência do significado do tratamento (Greene et al, 2009). …”

“…Esta hipótese tem sido apoiada por recentes estudos de neuroimagem, os quais sugerem que a analgesia placebo pode ocorrer pela estimulação da secreção de opióides endógenos e ativando as trajetórias descendentes de modulação da dor (Koshi et al, 2007).…”