Placebo and nocebo effects in youth: subjective thermal discomfort can be modulated by a conditioning paradigm utilizing mental states of low and high self-efficacy

Preserving the placebo effect after disclosure: A new perspective on non-deceptive placebos

The present study explores whether a particular style of placebo disclosure could serve as a tool to foster a renewed trust in one's own inherent resources and elicit a meaningful placebo effect. In a motor performance task, two placebo groups received inert transcutaneous electrical nerve stimulation (TENS) in each of four sessions along with information on its force-enhancing properties. Before the final session, one of the placebo groups was informed about the placebo, which was portrayed as a means to unleash an inherent potential. Along with force, we systematically monitored task-specific self-efficacy to test whether this variable would be differentially modulated in the two placebo groups. Compared to two control groups, placebo groups showed higher force and self-efficacy in the last session. No differences in self-efficacy were observed in the placebo groups even after revealing the placebo procedure, suggesting that the disclosure was effective in 'safeguarding' individuals' self-efficacy. These findings may have important implications, paving the way for the use of placebos that not only are ethically permissible but also support individuals' self-efficacy.

Placebo effects of transcranial direct current stimulation on motor skill acquisition

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique used in neurorehabilitation to enhance motor training. However, its benefits to motor training can be difficult to reproduce across research studies. It is possible that the observed benefits of tDCS are not directly related to the intervention itself but rather to the brain-mind responses elicited by the treatment context, commonly known as a placebo effect. This study investigated the presence of a placebo effect of tDCS on motor training and explored potential underlying factors. Sixty-eight participants who were right-handed were randomly assigned to active tDCS, sham tDCS, or a no-stimulation control group. Double-blind active or sham tDCS was applied to the right primary motor cortex, while the unblinded control group received no stimulation. All participants completed 30 training trials of a functional upper-extremity motor task. Participants' beliefs of tDCS, along with their prior knowledge of tDCS, were also collected. There was no significant difference in the amount of improvement on the motor task between the active and sham tDCS groups; however, both active and sham tDCS groups improved more than the control group, indicating a placebo effect. More motor task improvement was also associated with higher beliefs of tDCS (regardless of whether active or sham tDCS was received). This demonstrates a measurable placebo effect of tDCS on motor training, driven at least in part by treatment expectations or beliefs. Future tDCS studies should control for beliefs and other placebo-related factors.

Association between personality traits and placebo effects: a preregistered systematic review and meta-analysis

ABSTRACT

Placebo effects are ubiquitous yet highly variable between individuals and therefore strongly affect clinical trial outcomes such as pain relief. It is unclear whether dispositional psychological traits influence responsiveness to placebo. This preregistered meta-analysis and systematic review synthesized the literature investigating the association between personality traits and placebo effects. Based on 21 studies with 798 participants, we performed formal meta-analyses for 10 different personality traits, including behavioral inhibition, fun seeking, goal-drive persistence, reward responsiveness, empathic concern, empathic fantasy, perspective-taking, personal distress, optimism, and anxiety. We did not find evidence of associations between any of these traits and magnitude of placebo effects, which was supported by equivalence tests. Furthermore, we did not find evidence for moderating factors such as placebo manipulation type (conditioning or nonconditioning) or condition (pain or nonpain). These findings challenge the notion that personality influences responsiveness to placebos and contradict its utility for identifying placebo "responders" and "nonresponders."

Will This Treatment Help My Child?: How Parent/Caregiver Treatment Expectations Relate to Intensive Pain Rehabilitation Outcomes for Youth With Chronic Pain

OBJECTIVE

An extensive body of research has highlighted the impact that parent/caregiver factors have on functioning and treatment outcomes among youth with chronic pain. However, parent/caregiver expectations in pain treatment have been largely understudied, despite strong evidence that treatment expectations are associated with treatment engagement and overall outcomes in nonpain populations. Accordingly, the primary aim of this investigation was to preliminarily examine the manifestation and measurement of parent/caregiver treatment expectations in an intensive interdisciplinary pediatric pain treatment (IIPT) setting.

METHODS

Participants in this study (N=328) included children and adolescents who attended an IIPT program for chronic pain between August 2013 and March 2020 and their parent/caregiver(s). Outcomes examined include parent/caregiver self-report of treatment expectations for their child upon admission to the IIPT in addition to pain-related and psychosocial factors at admission and discharge.

RESULTS

Findings revealed a high level of expectations (ie, belief that the treatment will be helpful) on average, with higher parent/caregiver expectations associated with poorer functioning at admission to and discharge from the IIPT program.

CONCLUSION

Extremely high treatment expectations among parents of more disabled youth may be indicative of unrealistic hopes or the "need" for IIPT to help their child; tempering parental expectations with psychoeducation about IIPT goals and realistic outcomes may indirectly improve treatment outcomes for their children. Future research should examine the potentially unique and important role that treatment expectations, of both parent/caregivers and their children, may have in overall IIPT outcomes.