Smartphone Mindfulness Intervention Reduces Anxiety Symptoms and Perceived Stress in Autistic Adults: A Randomized Controlled Trial

Objectives: In-person mindfulness-based interventions (MBIs) have been shown to decrease symptoms of anxiety and stress in autistic adults, who often report high levels of these symptoms. Little is known about the effectiveness of remote MBIs for this population, which may be particularly useful given the common barriers autistic adults face in accessing in-person treatment. This study examined the feasibility and effectiveness of an app-based mindfulness intervention for autistic adults. Method: This randomized controlled trial (RCT) examined whether a 6-week remote intervention, using a customized version of the Healthy Minds Program app, reduced symptoms of anxiety and perceived stress in 89 autistic adults. Participants were randomly assigned to either the mindfulness intervention or a wait-list control (WLC) group. The WLC group received the intervention after the RCT. Self-report measures of anxiety, perceived stress, positive and negative affect, and trait mindfulness were administered at several timepoints. Results: The mindfulness group showed significant decreases in anxiety symptoms and perceived stress relative to the control group, with medium to large between-groups effect sizes (η_p² 0.07 to 0.14). These benefits, as well as significant decreases in negative affect and increases in trait mindfulness, were replicated when the WLC group subsequently received the intervention, and were retained in both groups 6 weeks after conclusion of the intervention. Conclusions: Results demonstrate both the feasibility and effectiveness of a remote mindfulness self-guided intervention for reducing perceived stress and anxiety symptoms in autistic adults. Future research can investigate the specific processes of how such an intervention exerts its effects. Preregistration: ClinicalTrials.gov TRN: NCT05880498, 5/30/23, retrospectively registered.