Effectiveness of Mindfulness-Based Stress Reduction Groups for Autistic Adults: A Randomized Clinical Trial

Background: Autistic adults often experience high levels of stress and difficulties in coping with stressors in everyday life. The aim of this study was to evaluate the effectiveness of mindfulness-based stress reduction (MBSR) groups, adjusted for autistic adults in an outpatient context. Methods: We conducted a two-arm, parallel-group, randomized controlled effectiveness trial during the years 2018–2020. Autistic adults ( N = 77) were recruited from outpatient services and randomized to either MBSR ( n = 39) or treatment as usual, TAU (i.e., continued regular services, n = 38). We used linear mixed models with random intercept to analyze the effects of intervention on self-rated perceived stress (primary outcome), as well as mental health, mindfulness skills, quality of life, and autism acceptance (secondary outcomes). In addition, we collected qualitative data at exit discussions in the MBSR groups and examined the transcription using thematic content analysis. Results: Participants (52% female) had a mean age of 40 years, with a majority being unemployed at the time of inclusion (64.9%) and having at least one co-occurring psychiatric diagnosis (87%). The completion rate in the MBSR group was 81%. A comparison of the slopes of the two groups showed a greater reduction of perceived stress from pre- to postintervention in the MBSR group than in the TAU group (Perceived Stress Scale total score: between-group effect size d = 0.55 [0.20–0.90] at postintervention and d = 0.61 [0.13–1.10] at the 3-month follow-up). Likewise, symptoms of mental health problems decreased more in the MBSR group (Hospital Anxiety and Depression Scale total score: between group d = 0.64 [0.23–1.05] at postintervention and d = 0.70 [0.14–1.26] at the 3-month follow-up). No changes in autism acceptance or general quality of life were observed in this study. Qualitative analysis indicated that participants perceived the MBSR group as inclusive and safe. Moreover, they appreciated both the conveyance of mindfulness techniques and the change in their approach (a “new mindset”) regarding stress. The participants also reflected on the challenges of continued practice after completed intervention. Conclusions: The MBSR groups for autistic adults may be an effective intervention in a clinical context. Future studies should examine the facilitators and barriers for the long-term maintenance of the acquired benefits.