Placebo effect in patients with algic syndrome

Abstract

Introduction: In recent years, the placebo effect has become more of a target of scientific inquiry, rather than a nuisance factor in clinical research setting. A better understanding of the neurobiology of the placebo and nocebo responses will represent the basis for designing behavioral protocols that can be employed as supportive therapy together with standard pharmacological regimen, in order to maximize the therapeutic outcome for the patients benefit. Objectives: to study the psychological profile of patients respondent and non-respondent to placebo; to study the factors that have an impact on the magnitude of placebo response; to study the autonomic profile of patients respondent and non-respondent to placebo; to determine sensitivity to placebo; to develop a screening test to estimate the sensitivity to placebo. Materials and methods: Subjects: a group of 15 patients with chronic migraine, selected according to HIS 2004 criteria, with average age of 29.9±2.6 years. Pain induction: pain was induced experimentally by means of the tourniquet technique. Drugs: for the placebo condition, calcium gluconate was administered; for analgesic control condition was used baralghetas. Results: This group was divided into respondent and non respondent to placebo subgroups. As criterion of division had served the decrease of the pain reported degree between control condition of natural flow and the placebo condition, with at least 10%. In the group respondent to placebo (8 patients, 53.3%), during the placebo condition, pain decreased by 23.17% (p<0.001) and pain tolerance value increased by 28.4% (p<0.05) compared to control condition of natural flow. For the SCL90 questionnaire scale were obtained higher degrees of non-respondents to placebo in comparison with respondents to placebo for the following scale: depression (2.03±0.01 in comparison with 1.35±0.08, p<0.001), anxiety (1.7±0.04 in comparison with 1.11±0.24, p<0.05), psychotic scale (1.45±0.06 in comparison with 0.98±0.2, p<0.05). Higher degrees of non-respondents to placebo were obtained on the following scales of autonomic profile (Ion Moldovanu 2011): anxiety and panic attacks (16±0 in comparison with 11.5±1.4, p<0.01), thermoregulation (40.5±5.9 in comparison with 20.33±3.4, p<0. 05). Degree of suggestibility was obtained higher among respondents to placebo compared to non-respondents. Conclusion: In patients with chronic migraine the presence of placebo response depends on anxiety, depression and the degree of suggestibility. Thus it is possible to perform a screening test containing questions from the questionnaire scales used, where there have been registered statistically significant differences between the groups respondent and non-respondent to placebo.