Mindfulness-based Emotional Regulation Versus ACT in Anxiety

Background: There is a paucity of randomized clinical trials which address the relationship between training in mindfulness and neuropsychological outcomes. Also, how psychotherapeutic interventions were delivered before and during the COVID-19 pandemic and its possible differential results need more scientific attention. Aims: To compare the effectiveness of an intervention based on the Acceptance and Commitment Therapy (ACT) versus a Mindfulness-based Emotional Regulation (MER) intervention among adult patients with anxiety disorders. Methods: This randomized, single-blind, clinical trial is being conducted in a community Mental Health Unit (Colmenar Viejo, Madrid) in Spain. Potential outpatients will be over 18 years (until 75 years) with some type of specific or unspecified anxiety disorder. They will be assessed for inclusion/exclusion criteria and randomized according to the score on the Acceptance and Action Questionnaire-II (used as a blocking factor). One of the interventions was adapted from the Acceptance and Commitment Therapy (ACT) for anxiety disorders and MER was based on the Mindfulness-Based Stress Reduction program. Each intervention has been designed to be weekly, during 8 weeks, guided by two Clinical Psychology residents. Interventions have been delivered face-to-face before the COVID-19 pandemic, or via online currently. A 2x3 mixed-factorial ANOVA (intervention type x pre-treatment, post-treatment and 6-month follow-up) will be conducted, with Sidak-correction post hoc tests. The primary measures are the TMT score (A and B forms), Stroop test, Digit span subtests from the Wechsler Adult Intelligence Scale, version IV (Forward, Backward and Sequencing subtests), Acceptance and Action Questionnaire-II, and Anxiety Sensitivity Index-3 (ASI-3). Secondary measures are the Five Facets Mindfulness Questionnaire (FFMQ), Toronto Alexithymia Scale 20-item (TAS-20), Reflective Functioning Questionnaire (RFQ-8), Hospital Anxiety and Depression Scale (HADS), and the World Health Organization\'s Quality of Life Questionnaire (WHOQOL-BREF). Norms based on the Spanish general population will be used. Results: This clinical trial started in February 2019 and it is expected to end in September 2023. The minimum sample size required is 128 participants (64 each intervention) to achieve medium effect sizes on primary outcomes (alfa = .05 and beta = .20). So far, 107 adult patients with anxiety disorders participated (64 participants in face-to-face interventions before the COVID-19 pandemic; and 43 participants via online, during the pandemic). Conclusions: This is the first study to compare two mindfulness-based interventions on several neurocognitive functions and other psychological domains among adult patients with anxiety disorders.