The influence of personality traits on the placebo/nocebo response: A systematic review.
Kern AInstitute for Complementary and Integrative Medicine, University Hospital Zurich and University of Zurich, Zurich, Switzerland. Electronic address: alexandra.kern@usz.ch.
Kramm CInstitute for Complementary and Integrative Medicine, University Hospital Zurich and University of Zurich, Zurich, Switzerland.
Witt CMInstitute for Complementary and Integrative Medicine, University Hospital Zurich and University of Zurich, Zurich, Switzerland; Institute for Social Medicine, Epidemiology and Health Economics, Charité Universitätsmedizin Berlin, Berlin, Germany; Center for Integrative Medicine, University of Maryland, School of Medicine, Baltimore, MD, USA.
Barth JInstitute for Complementary and Integrative Medicine, University Hospital Zurich and University of Zurich, Zurich, Switzerland.
English
OBJECTIVE Some people might be more prone to placebo and nocebo responses than others depending on their personality traits. We aimed to provide a systematic review on the influence of personality traits on placebo and nocebo responses in controlled and uncontrolled studies.
METHODS We conducted a systematic literature search in the databases CINAHL, AMED, PsycINFO and EMBASE for relevant publications published between January 1997 and March 2018. For all included papers, we conducted an additional forward search.
RESULTS After screening 407 references, we identified 24 studies. The Big Five (i.e., neuroticism, extraversion, openness to experience, agreeableness and conscientiousness) and optimism were the most frequently investigated personality traits. Several studies found a positive association between optimism and the placebo response. Furthermore, we found that higher anxiety was associated with increased nocebo responses.
CONCLUSION Evidence points to a possible association between optimism and the placebo response. Therefore, further emphasising the investigation of the influence of optimism on the placebo/nocebo response seems warranted. For clinical practice, the impact of anxiety on the nocebo response might be important to identify patients who might be more prone to experiencing side effects of medical treatments.