Introduction
borderline personality disorder, contamination-based obsessive, anxiety, ’, compulsive disorder, pain, reduced emotional distress, OLP
Several neuroimaging studies have shown that placebos can reduce the intensity of negative affective states. For example, inert pills administered as ‘analgesics’, ‘anxiolytics’, or ‘anti-nausea medication’ can alleviate feelings of social rejection (emotional pain), anxiety, and disgustDespite these positive effects, the prescription of ‘deceptive placebos’ is surrounded by serious ethical issues. The lack of informed consent and transparency of treatment prohibits the clinical use of placebos. One approach that circumvents these ethical issues is the administration of open-label placebos (OLPs), which are presented to a person openly and honestly, without any deception regarding their natureThe beneficial outcomes of OLP treatment for reducing emotional distress have been documented primarily using self-report measures. To the best of our knowledge, only three OLP studies have recorded neurobiological indicators of affective processing. In a functional magnetic resonance imaging (fMRI) study by Schaefer et al.The LPP effects observed in the above-mentioned OLP studies (specifically, the reduction of frontal and centroparietal LPP amplitudes due to OLP treatment) shared striking similarities with findings from previous EEG experiments focusing on cognitive reappraisal [CRA direct comparison of OLP treatment and CR could provide important insights into the underlying neural mechanisms of the two approaches. Functional magnetic resonance imaging (fMRI), a neurobiological method with excellent spatial resolution, presents itself as one effective approach for identifying brain networks involved in these interventions. It has been shown that the downregulation of negative emotional states using CR involves cognitive control regions in frontal areas of the brain (e.g., VLPFC/DLPFC). These areas modulate activity in (sub)cortical regions concerned with the decoding of stimulus salience (e.g., amygdala, insula; see meta-analysisAside from establishing the effectiveness of OLPs on a subjective as well as neurobiological level, it is also important to investigate whether this type of intervention is found to be plausible by the treated individuals. Some recent studies have indicated that the concept of OLPs is not always perceived as intuitive by the placebo recipients [e.g.,The current study with functional magnetic resonance imaging (fMRI) compared the effects of an OLP pill with CR for reducing a specific form of emotional distress: disgust. This basic emotion plays an important role in a wide range of psychopathology, including contamination-based obsessive–compulsive disorder, specific phobia (spider/blood), borderline personality disorder, and eating disordersThe present investigation explored whether an OLP can have similar disgust-reducing effects. The participants were randomly allocated to one of three groups (OLP, CR, PV: passive viewing), all of which were exposed to disgusting and neutral images. Ratings of disgust elicited by the pictures were assessed. It was hypothesized that participants of the OLP/CR groups would report less intense disgust feelings compared to the PV group. The reduced emotional distress should be accompanied by altered activity in prefrontal cognitive control regions (e.g., DLPFC, VLPFC, ACC) as demonstrated before in fMRI studies focusing on the effects of CR