Peak experiences and the afterglow phenomenon: When and how do therapeutic effects of hallucinogens depend on psychedelic experiences?

Interest in using psychedelic substances therapeutically has revived. Early research suggested they could help with various conditions, and recent clinical applications include cluster headaches, obsessive-compulsive disorder, addiction, and fear and anxiety in terminal illness, pointing to possibly different therapeutic mechanisms. Psychotherapeutic approaches emphasize subjective experiences like peak experiences or afterglow phenomena as key to therapeutic action. This review re-evaluates older and newer concepts of how psychedelics may produce benefits, discussing neurophenomenological aspects and different psychotherapeutic uses. Evidence shows that while pharmacological and psychological actions are not clearly separable, they appear to contribute differently depending on the pathology.

Study at a glance

Abstract

Interest in the therapeutic potential of psychedelic substances has recently resumed. During an early phase of human psychedelic research, their therapeutic application in different pathologies had been suggested, and the first evidence for efficacy was provided. The range of recent clinical applications of psychedelics spans from cluster headaches and obsessive-compulsive disorder to addiction and the treatment of fear and anxiety in patients suffering from terminal illness, indicating potentially different therapeutic mechanisms. A variety of approaches in psychotherapy emphasize subjective experiences, such as so-called peak experiences or afterglow phenomena, as differentially mediating therapeutic action. This review aims to re-evaluate earlier and recent concepts of how psychedelic substances may exert beneficial effects. After a short outline of neurophenomenological aspects, we discuss different approaches to how psychedelics are used in psychotherapy. Finally, we summarize evidence for the relationship between subjective experiences and therapeutic success. While the distinction between pharmacological and psychological action obviously cannot be clear-cut, they do appear to contribute differently from each other when their effects are compared with regard to pathologies.