Does patient expectancy account for the cognitive and clinical benefits of mindfulness training in older adults?

Objectives: Patient expectations of treatment effects could influence neuropsychological and clinical outcomes in clinical trials of behavioral and lifestyle interventions, which could potentially confound the interpretation of findings. Our aim was to examine whether patient expectancy mediated effectiveness of Mindfulness-Based Stress Reduction (MBSR) for improving cognitive function and clinical outcome.

Methods: The present study uses data from a single-blind, multi-site, randomized controlled trial comparing MBSR to a health education attention control in older adults with anxiety and/or depressive disorders and subjective cognitive concerns. Using the Credibility and Expectations Questionnaire, we measured expectancy and perceived credibility of the interventions assigned to patients. Using mediational analysis, we examined the influence of expectancy and credibility on two key outcomes: memory performance and clinical global improvement.

Results: Neither expectancy nor perceived credibility of intervention accounted significantly for MBSR's effectiveness for memory test performance or clinical global improvement.

Conclusion: In this clinical trial, expectancy for improvement did not account for the effectiveness of MBSR on memory performance or clinical outcomes in depressed and anxious older adults. We advise that clinical trials of behavioral and lifestyle interventions for brain health in older adults should measure and test the role of expectancy.