Hallucinogenic Persisting Perception Disorder: A Case Series and Review of the Literature
Frontiers in Neurology May 6, 2022 Hannah Ford, Clare L. Fraser, Emma J. Solly et al. 28 citations
Hallucinogen persisting perception disorder (HPPD) involves the return of perceptual symptoms after stopping hallucinogens. In a series of 13 patients and a review of 24 case reports, LSD, MDMA, and cannabinoids were commonly used, often together. The most frequent symptoms were visual snow, floaters, palinopsia, photophobia, and nyctalopia. Most ophthalmic and neurologic tests were normal. Two patients fully recovered, one with benzodiazepine treatment and one without; 25% of literature cases fully recovered. The symptoms overlap with Visual Snow Syndrome, suggesting that HPPD may be a secondary cause of VSS and that diagnostic criteria for HPPD should include visual snow, nyctalopia, photophobia, and floaters.