Can verbal suggestions strengthen the effects of a relaxation intervention?

Mindfulness Effects on Anxiety: Disentangling the Role of Decentering and Treatment Expectations

Mindfulness interventions have been found to lower anxiety. However, the current literature has not adequately considered the role of its individual components and of placebo effects. In an online experiment using a balanced placebo design, we aimed to disentangle effects of decentering, a key component of mindfulness, and expectations, a key component of placebo effects, on anxiety related to the COVID-19 pandemic. One hundred twenty-eight adults were randomly assigned to one of four groups: placebo/mindful decentering, placebo/sham decentering, sham/mindful decentering, and sham/sham decentering. Instructions were provided using standardized audio instructions. Current anxiety was assessed pre- and postintervention with the Short State version of the State-Trait Anxiety Inventory. Mindful decentering was found to reduce anxiety postintervention, as compared to sham decentering, regardless of induced expectations regarding its effectiveness. Participants in the mindful decentering group also mentioned more decentering-related words than those in the sham decentering group. These findings indicate that a short, standardized, and online mindful decentering intervention can effectively decrease pandemic-related anxiety independently of one's expectations. These findings provide insights into the efficacy of the individual elements of mindfulness, highlighting decentering as an effective active component for anxiety relief. Moreover, these findings suggest that, in a nonclinical sample, individuals can apply mindful decentering with minimal training.

The role of self-reported and physiological stress in nocebo hyperalgesia

Negative expectations can increase pain sensitivity, leading to nocebo hyperalgesia. However, the physiological and psychological factors that predispose individuals to this phenomenon are still not well understood. The present study examined whether stress induced by a social stressor affects nocebo hyperalgesia, and whether this effect is mediated by self-reported and physiological stress responses. We recruited 52 healthy participants (15 men) who were randomly assigned to either the Trier Social Stress Test (TSST) or a control condition (a friendly version of the TSST). Nocebo hyperalgesia was induced using negative suggestions combined with a validated pain conditioning paradigm. We assessed self-reported (anxiety and stress) and physiological (cortisol, alpha-amylase, heart rate, and skin conductance) responses to stress. Both groups exhibited significant nocebo hyperalgesia. The stress group showed higher levels of anxiety, self-reported stress, and cortisol levels compared to the control group while no significant differences were found in other physiological markers. The stress and control groups did not differ in the magnitude of nocebo hyperalgesia, but anxiety levels partially mediated the effects of the stress test on nocebo hyperalgesia. Our findings suggest that an external social stressor does not directly affect nocebo hyperalgesia, but that increased anxiety due to the stressor enhances its magnitude. Thus, it may be worthwhile to investigate whether reducing stress-related anxiety in clinical settings would help alleviate nocebo effects.

The Optimal Learning Cocktail for Placebo Analgesia: A Randomized Controlled Trial Comparing Individual and Combined Techniques

This study investigated for the first time the effects of individual and combined application of 3 learning techniques (verbal suggestions, classical conditioning, and observational learning) on placebo analgesia and extinction. Healthy participants (N = 206) were assigned to 8 different groups in which they were taught through either a verbal suggestion, a conditioning paradigm, a video observing someone, or any combination thereof that a placebo device (inactive transcutaneous electric nerve stimulation [TENS]) was capable of alleviating heat pain, whereas one group did not (control). Placebo analgesia was quantified as the within-group difference in experienced pain when the placebo device was (sham) 'activated' or 'inactivated' during equal pain stimuli, and compared between groups. Placebo analgesia was induced in groups with 2 or 3 learning techniques. Significantly stronger placebo analgesia was induced in the combination of all 3 learning techniques as compared to the individual learning techniques or control condition, underlining the additional contribution of 3 combined techniques. Extinction did not differ between groups. Furthermore, pain expectancies, but not state anxiety or trust, mediated placebo analgesia. Our findings emphasize the added value of combining 3 learning techniques to optimally shape expectancies that lead to placebo analgesia, which can be used in experimental and clinical settings. PERSPECTIVE: This unique experimental study compared the individual versus combined effects of 3 important ways of learning (verbal suggestions, classical conditioning, and observational learning) on expectation-based pain relief. The findings indicate that placebo effects occurring in clinical practice could be optimally strengthened if healthcare providers apply these techniques in combination.

Optimising the efficacy of a stress-reducing psychological intervention using placebo mechanisms: A randomized controlled trial

This study examined whether i) brief videos aiming to optimise outcome expectations would augment the efficacy of progressive muscle relaxation (PMR) and ii) whether participants' characteristics would moderate these effects. Sixty-eight healthy subjects randomized to one of three experimental manipulations before undergoing a single PMR session either watched i) a video displaying a neutral expert, ii) a video with a warm expert, or iii) were part of an active control condition. Constrained linear mixed models indicated increased relaxation and decreased stress levels for all participants after the PMR session. The primary outcome was the change of perceived relaxation/stress from pre to post. Participants with high neuroticism and trait anxiety indicated an augmented PMR's efficacy and increased outcome expectations when watching the warm expert video compared to the control group or the less warm expert. Brief videos displaying an expert aiming to optimise outcome expectations regarding a brief stress-reducing psychological intervention may boost or decrease an intervention's efficacy. Effects may depend on the viewer's personality and the (video) expert's communication style. Trial Registration: The study protocol was approved by the local Ethics Committee of the University of Marburg, Germany. This study was registered at www.clinicaltrials.gov (NCT03330431).