On Perception and Consciousness in HPPD: A Systematic Review
Frontiers in Neuroscience August 11, 2021 Pieter J. Vis, Anneke E. Goudriaan, Bastiaan C. Ter Meulen et al. 40 citations
Hallucinogen-persisting perception disorder (HPPD) involves perceptual symptoms and flashbacks after psychedelic use, but its phenomenology is poorly understood. A systematic review of 66 case reports and series covering 97 people identified 64 unique symptoms. Of these, 76% were characteristic of Alice in Wonderland syndrome, over 50% were non-visual, and 38% were not clearly linked to prior intoxication, contrasting with DSM-5 criteria. Fewer than half of patients had a protracted course over a year, and a third achieved remission. Co-occurring depression with or without anxiety was associated with longer symptom persistence and more negative treatment outcomes. HPPD involves changes in the content of consciousness and an attentional shift from external to internal phenomena, rather than the altered states seen in acute intoxication. The authors recommend expanding diagnostic criteria.