Neuropsychological profiles of patients suffering from hallucinogen persisting perception disorder (HPPD): A comparative analysis with psychedelic-using and non-using controls

Classic psychedelics like LSD and psilocybin show promise for treating psychiatric disorders but can occasionally cause lasting psychological harm, including Hallucinogen Persisting Perception Disorder (HPPD), a rare condition with enduring perceptual symptoms. This study examined the neuropsychological profiles of eight individuals with HPPD using a comprehensive test battery, comparing their performance against normative data and two matched control groups (with and without prior psychedelic use). Some participants with HPPD scored below average on tests of visual memory and executive function. Statistically adjusted comparisons found no significant differences between groups, though unadjusted analyses hinted at impaired executive functions in HPPD patients. These preliminary findings highlight the need for more focused research on the neuropsychological aspects of HPPD.

Study at a glance

Abstract

Abstract Classic psychedelics like LSD and psilocybin are showing promising effects in treating certain psychiatric disorders. Despite their low toxicity and lack of an addictive potential, in some individuals, psychedelics can be associated with persisting psychological harms. Hallucinogen Persisting Perception Disorder (HPPD) is one of those complications, a rare disorder characterized by enduring perceptual symptoms without impaired reality control. While the phenomenological aspects of HPPD have been characterized, the neuropsychological consequences have remained understudied. This study probes the neuropsychological profiles of eight individuals with HPPD, utilizing a comprehensive test battery. Performance is benchmarked against normative data and compared with two control groups, each comprising eight matched subjects—with and without prior psychedelic use. The assessment of individual performances revealed below average results in tests of visual memory and executive function in some subjects. No significant differences were observed in alpha-adjusted comparisons with controls, whereas unadjusted analyses were suggestive of impaired executive functions among HPPD patients. Together, these preliminary results underline the need for further focused research into the neuropsychological dimensions of HPPD.