Contemporary research with classic psychedelic drugs (e.g., lysergic acid diethylamide (LSD) and psilocybin) is indebted to the twentieth-century researchers and clinicians who generated valuable clinical knowledge of these substances through experimentation. Several recent reviews that highlight the contributions of this early literature have focused on psychedelic-assisted individual psychotherapy modalities. None have attempted to systematically identify and compile experimental studies of psychedelic-assisted group therapy. In therapeutic settings, psychedelics were often used to enhance group therapy for a variety of populations and clinical indications. We report on the results of a systematic review of the published literature in English and Spanish on psychedelic-assisted group therapies. Publications are characterized by their clinical approach, experimental method, and clinical outcomes. Given the renewed interest in the clinical use of psychedelic medicines, this review aims to stimulate hypotheses to be tested in future research on psychedelic-assisted psychotherapy, group process, and interpersonal functioning.

Objective

This study tested whether a mindfulness-based intervention for obesity that included components aimed at emotion regulation and mindful eating improved psychological outcomes including stress, anxiety, positive emotion, and depression, during the intervention period and at longer-term follow-up.

Methods

Adults with obesity (N=194) were randomized to a 5.5-month diet-exercise weight loss intervention with or without mindfulness training focused on emotion regulation and mindful eating. Participants completed self-report measures of mindfulness and psychological well-being, which were planned secondary outcomes, at baseline, mid-intervention (3 months), and at 6-, 12-, and 18-months post-baseline (maintenance period). Mixed effects models and linear regression were used to test between- and within-group changes in psychological well-being. Finally, this study explored whether changes in mindfulness (from baseline to each 6- and 18-months post-baseline) mediated the effects of intervention arm on changes in psychological outcomes during those respective time periods. This study explored whether changes in mindfulness from baseline to 6 months mediated the effects of intervention arm on changes in psychological outcomes from baseline to 18 months.

Results

Participants randomized to the mindfulness arm had significant increases in positive emotions at all follow-up times compared to controls. There were statistically significant increases in mindfulness, psychological flexibility, and reflection, as well as decreases in anxiety and depressive symptoms at 12 months compared to control participants. These changes remained significant for psychological flexibility and reflection at 18 months. There were no significant differences in perceived stress. Among mindfulness participants, greater increases in mindfulness from 6-18 months was associated with greater positive emotions and psychological flexibility as well as lower perceived stress, anxiety, depressive symptoms, and rumination at 18 months, adjusting for 6-month values. Mediation analyses indicated that randomization to the mindfulness intervention arm was associated with 6-month increases in mindfulness, and these increases were in turn associated with improved psychological outcomes at 6 months and 18 months. Changes from baseline to 18 months did not mediate 18-month changes in psychological outcomes.

Conclusions

Mindfulness training in emotion regulation and mindful eating may provide greater longer-term psychological well-being benefits in non-clinical populations with obesity compared to conventional diet-exercise interventions.