Division of Clinical Psychology and Psychiatry, Department of Psychology, University of Basel, Basel, Switzerland.
Department of Clinical Psychology and Cognitive Behavioral Therapy, International Psychoanalytic University Berlin, Berlin, Germany.
JMIR Mhealth Uhealth. 2021 Feb 17;9(2):e20329. doi: 10.2196/20329.
There is certain evidence on the efficacy of smartphone-based mental health interventions. However, the mechanisms of action remain unclear. Placebo effects contribute to the efficacy of face-to-face mental health interventions and may also be a potential mechanism of action in smartphone-based interventions.
This study aimed to investigate whether different types of efficacy expectancies as potential factors underlying placebo effects could be successfully induced in a smartphone-based digital placebo mental health intervention, ostensibly targeting mood and stress.
We conducted a randomized, controlled, single-blinded, superiority trial with a multi-arm parallel design. Participants underwent an Android smartphone-based digital placebo mental health intervention for 20 days. We induced prospective efficacy expectancies via initial instructions on the purpose of the intervention and retrospective efficacy expectancies via feedback on the success of the intervention at days 1, 4, 7, 10, and 13. A total of 132 healthy participants were randomized to a prospective expectancy-only condition (n=33), a retrospective expectancy-only condition (n=33), a combined expectancy condition (n=34), or a control condition (n=32). As the endpoint, we assessed changes in efficacy expectancies with the Credibility Expectancy Questionnaire, before the intervention and on days 1, 7, 14, and 20. For statistical analyses, we used a random effects model for the intention-to-treat sample, with intervention day as time variable and condition as two factors: prospective expectancy (yes vs no) and retrospective expectancy (yes vs no), allowed to vary over participant and intervention day.
Credibility (β=-1.63; 95% CI -2.37 to -0.89; P<.001) and expectancy (β=-0.77; 95% CI -1.49 to -0.05; P=.04) decreased across the intervention days. For credibility and expectancy, we found significant three-way interactions: intervention day×prospective expectancy×retrospective expectancy (credibility: β=2.05; 95% CI 0.60-3.50; P=.006; expectancy: β=1.55; 95% CI 0.14-2.95; P=.03), suggesting that efficacy expectancies decreased least in the combined expectancy condition and the control condition.
To our knowledge, this is the first empirical study investigating whether efficacy expectancies can be successfully induced in a specifically designed placebo smartphone-based mental health intervention. Our findings may pave the way to diminish or exploit digital placebo effects and help to improve the efficacy of digital mental health interventions.
Clinicaltrials.gov NCT02365220; https://clinicaltrials.gov/ct2/show/NCT02365220.
有一定证据表明智能手机为基础的心理健康干预措施是有效的。然而，其作用机制仍不清楚。安慰剂效应有助于面对面的心理健康干预措施的疗效，也可能是基于智能手机的干预措施的潜在作用机制。
本研究旨在探讨在基于智能手机的数字安慰剂心理健康干预中，是否可以成功诱导不同类型的疗效期望作为安慰剂效应的潜在因素，这种干预表面上针对的是情绪和压力。
我们进行了一项随机、对照、单盲、优效性试验，采用多臂平行设计。参与者接受了为期 20 天的基于 Android 智能手机的数字安慰剂心理健康干预。通过对干预目的的初步说明来诱导预期疗效，通过在第 1、4、7、10 和 13 天对干预成功的反馈来诱导回顾性疗效期望。共有 132 名健康参与者被随机分配到预期疗效仅观察条件（n=33）、回顾性预期疗效仅观察条件（n=33）、联合预期疗效条件（n=34）或对照组（n=32）。作为终点，我们在干预前和第 1、7、14 和 20 天使用信任期望问卷评估疗效期望的变化。对于统计分析，我们对意向治疗样本使用随机效应模型，以干预日为时间变量，以条件为两个因素：前瞻性期望（是 vs 否）和回顾性期望（是 vs 否），允许在参与者和干预日之间变化。
信任度（β=-1.63；95%置信区间-2.37 至-0.89；P<.001）和期望（β=-0.77；95%置信区间-1.49 至-0.05；P=.04）在干预日期间呈下降趋势。对于信任度和期望，我们发现了显著的三向交互作用：干预日×前瞻性期望×回顾性期望（信任度：β=2.05；95%置信区间 0.60-3.50；P=.006；期望：β=1.55；95%置信区间 0.14-2.95；P=.03），这表明在联合预期疗效条件和对照组中，疗效期望下降最少。
据我们所知，这是第一项实证研究，旨在探讨是否可以在专门设计的基于安慰剂的智能手机心理健康干预中成功诱导疗效期望。我们的研究结果可能为减少或利用数字安慰剂效应并帮助提高数字心理健康干预措施的疗效铺平道路。
Clinicaltrials.gov NCT02365220；https://clinicaltrials.gov/ct2/show/NCT02365220。
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