Sham-neurofeedback as an Intervention: Placebo or Nocebo?

Abstract

IntroductionSham-controlled studies of neurofeedback are aimed to provide evidence-based data regarding its efficacy. However, a sophisticated sham procedure may turn out to be an intervention rather that a neutral control.MethodsData from a single-case cross-over sham-controlled study of NF in migraine were analyzed to access the effects of sham-NF. The study included 5 females with chronic migraine and was divided into 4 phases: pre-evaluation (≥ 2 weeks), treatment 1 (5 weeks), treatment 2 (5 weeks), post-evaluation (≥ 2 weeks), where treatment 1 and 2 included 10 infra-low frequency NF and 10 sham-NF sessions at T3T4 site in randomized order. Participants filled out a computerized diary about headache and emotions.ResultsSham-NF resulted in some reduction of the level of tension (0.8 ± 0.7 vs. 1.1 ± 0.5, P = 0.1) and anxiety (0.56 ± 0.5 vs. 0.95 ± 0.4, P = 0.07) as measured by the mean value in the diary (rating from 0 - no emotion, to 3 - very intense). While the total frequency of headache was not influenced by sham-NF (40 ± 11% vs. 40 ± 7% days, P = 1), a tendency towards an increase in quantity of severe headaches (42 ± 18% vs. 20 ± 18% days, P = 0.07) and in the need for drug intake (74 ± 27% vs. 44 ± 30% days, P = 0.07) was observed. We supposed that expectation of feedback and failure to receive it during sham sessions may have possible negative effects, while frequent visits to the clinic and contact with the therapist may explain reduction in anxiety.ConclusionSham-NF seems to have both placebo and nocebo effects, which should be considered during interpretation of results of the studies.Disclosure of interestThe authors have not supplied their declaration of competing interest.