Flashbacks and HPPD: A Clinical-oriented Concise Review

This review (2014) examines the cause of flashbacks or Hallucinogen Persisting Perception Disorder (HPPD), which represents a cluster of recurrent visual disturbances which have been reported to persist after the acute phase of psychedelics, such as LSD. The authors delineate HPPD type I disorder: short-term, non-distressing, benign, and reversible state accompanied by a pleasant affect, and type II: long-term, distressing, pervasive, either slowly reversible or irreversible, non-benign state accompanied by an unpleasant affect. Although the prevalence of HPPD remains understudied, the authors review a large variety of medications that may alleviate the symptoms of this condition.

Abstract

“A unique characteristic of LSD, LSD-like and substances with hallucinogenic properties is the recurrence of some or all the hallucinogenic symptoms which had appeared during the intoxication after the immediate effects of the substance had worn off. This recurring syndrome, mainly visual, is not clearly understood. The terms Flashback and Hallucinogen Persisting Perception Disorder (HPPD) have been used interchangeably in the professional literature. We have observed at least two different recurrent syndromes, the first Flashback Type we refer to as HPPD I, a generally short-term, non-distressing, benign and reversible state accompanied by a pleasant affect. In contrast, the second HPPD Type we refer to as HPPD II, a generally long-term, distressing, pervasive, either slowly reversible or irreversible, non-benign state accompanied by an unpleasant affect. HPPD I and II appear to be part of a broad spectrum of non-psychopathological and psychopathological states reported by hallucinogen users. HPPD I and II may be clinically characterized by prodromal symptoms, onset, content of visual imagery, precipitators, frequency, duration and intensity of perceptual recurrences, severity, course, differential diagnosis, accompanying mood and affect, insight and remission. Pharmacological therapy with or without preceding or following co-occurring psychiatric disorders have been shown to ameliorate this syndrome. A large variety of medications may be utilized to alleviate this condition, but with differential results suggesting several subtypes. The purpose of this manuscript is to provide a clinical-oriented, comprehensive and concise review to treating psychiatrists.”

Authors: Arturo G. Lerner, Dmitri Rudinski, Oren Bor & Craig Goodman

Summary of Clonazepam treatment of LSD-induced HPPD disorder with anxiety features

Hallucinogens include naturally occurring and synthetic substances that may trigger a transient and generally reversible state of intoxication characterized by perceptual disturbances primarily visual in nature, often referred to as “trips”. LSD is the prototype of synthetic hallucinogens and is probably the most investigated hallucinogen associated with the development of this condition.

LSD’s acute effects seem to emerge through a 5-HT 2 postsynaptic partial agonist activity, and vulnerable LSD users may develop chronic disinhibition of visual processors and consequent dysfunction in CNS function. Investigations of HPPD patients with qEEG mapping indicate that disinhibition in the cerebral cortex is involved in the pathogenesis of this syndrome. Reverse tolerance or sensitization that had originated after LSD exposure may also explain the flashbacks.