Meditation and psychedelics have played key roles in humankind’s search for self-transcendence and personal change. However, neither their possible synergistic effects, nor related state and trait predictors have been experimentally studied. To elucidate these issues, we administered double-blind the model psychedelic drug psilocybin (315 μg/kg PO) or placebo to meditators (n = 39) during a 5-day mindfulness group retreat. Psilocybin increased meditation depth and incidence of positively experienced self-dissolution along the perception-hallucination continuum, without concomitant anxiety. Openness, optimism, and emotional reappraisal were predictors of the acute response. Compared with placebo, psilocybin enhanced post-intervention mindfulness and produced larger positive changes in psychosocial functioning at a 4-month follow-up, which were corroborated by external ratings, and associated with magnitude of acute self-dissolution experience. Meditation seems to enhance psilocybin’s positive effects while counteracting possible dysphoric responses. These findings highlight the interactions between non-pharmacological and pharmacological factors, and the role of emotion/attention regulation in shaping the experiential quality of psychedelic states, as well as the experience of selflessness as a modulator of behavior and attitudes. A better comprehension of mechanisms underlying most beneficial psychedelic experiences may guide therapeutic interventions across numerous mental conditions in the form of psychedelic-assisted applications.

Lysergic acid diethylamide (LSD) and similar psychoactive drugs have been used in psychotherapy since 1949, when the first clinical study with lower-dose LSD showed therapeutically relevant effects. This caused an intense interest among psychotherapists and researchers, alike, on an international scale. In 1960, the use of serial lower-dose LSD/psilocybin sessions in a psychoanalytical framework, which was dominant at the time, was named “psycholytic therapy”. Psycholytic therapy was usually conducted in clinical environments, on both an inpatient and outpatient basis. Psycholytic therapy was developed and established over a 15-year period on the European continent, where it was used at 30 clinical treatment centers and by more than 100 outpatient psychotherapists. Psycholytic approaches were employed minimally in North America, where the psychedelic approach (use of one or two high-dose sessions for “personality-transforming mystical experiences”) became the dominant method in use. The leading figure in psycholytic therapy was Professor Hanscarl Leuner in Germany, who laid the ground with his uniquely fine grained analysis of the LSD reaction in a 1962 monograph. He was central in establishing and distributing psycholytic therapy in Europe and abroad. The article provides comprehensive background information and outlines the essential features of psycholytic therapy. Evidence for the efficacy of psycholytic therapy is reviewed and a case for the inclusion of the psycholytic approach in the field of substance-assisted psychotherapy is made.