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Case report - Hallucinogen Persisting Perceptual Disorder


Hallucinogens are mind altering natural or synthetic agents which can produce state of intoxication with changes in mood, thoughts and perception. One of the unique characteristics of hallucinogens, especially LSD, has been the recurrence of symptoms even in absence of recent intake. This recurrence has been mostly described as visual disturbance in the form of geometric figures, flashes of colors, a trail of images of moving objects, positive afterimages, halos around objects, micropsia, or macropsia(1-2). Some LSD users think of such experiences as “free trips” and never seek treatment but most find it distressing and look for treatment.


  • The reexperiencing, following cessation of use of a hallucinogen, of one or more of the perceptual symptoms that were experienced while intoxicated with the hallucinogen.
  • The symptoms in criteria A cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.
  • The symptoms are not due to general medical condition or by another mental disorder.

Possible mechanism

Effects of LSD seem to be mediated through a 5HT-2 postsynaptic partial agonist activity. LSD generated dysfunction of cortical serotonergic inhibitory interneurons with GABAergic outputs might be a possible explanation for the recurrence of visual experience, based on continuation of central process of visual imagery due to chronic disinhibition of visual processes.(4)

Case report

 Since the recurrence of symptoms can occur even several years after hallucinogen use, it can be easily misdiagnosed as psychosis. We are reporting a similar case where it took several years before diagnosis of HPPD was reached and patient was able to get appropriate treatment.

The patient was a 42 year old Caucasian male with history of using LSD heavily in past. After remaining clean for several years he started having visual hallucinations of haloes around objects, and as result became depressed. He was referred to psychiatrist who diagnosed him with schizoaffective disorder depressed type and was prescribed Mellaril. Patient showed no improvement in his hallucinations or depressive symptoms even after several months on the medication. Psychiatrist than thought of bipolar disorder and psychotic disorder NOS diagnosis. And patient was tried on Stelazine, Risperidone, and Triavil over next two years with no positive outcome.

The patient could not function professionally due to these “visual trips”. His increasing frustration made his depression worse. At that time patient decided to change his psychiatrist.

The new psychiatrist took a more thorough history and found out that the patient was suffering from HPPD and depression.

The patient was prescribed Zoloft and responded well with as far a depressive symptoms were concerned but continued to experience visual hallucinations. At that time the patient was referred to a different clinic because of heavy alcohol use.

After initial evaluation there the impression was that the patient was suffering from untreated HPPD and depression. Zoloft was maintained and clonazepam started to counter “visual trips”. Clonazepam was initially started at 1.5 mg initially and maintained at same dose. Patient responded positively to clonazepam and within few weeks his hallucinations were more than 50% better. And with in 3-4 months showed 80% improvement. Zoloft was later switched to Wellbutrin because of sexual side effects. Patient was able to remain euthymic even after switching to Wellbutrin. With improvement of his visual hallucinations the patient was also able to stop his alcohol use. The patient was also able to resume his normal day to day professional activities.


The literature on the efficacy of psychopharmacology in HPPD is mostly supported by some case reports. Benzodiazepines, haloperidol, perphanazine, clonidine, naltrexone, sertraline (5-6) are some of the medications that have been shown to be helpful. This could be explaiend if HPPD is a syndrome which includes several subtypes. The present case showed sustained improvement with clonazepam. The decision to prescribe clonazepam was based on the failure of antipsychotics or antidepressants. The patient’s alcohol use was interpreted as an effort to self medicate and did not alter the treatment team's decision for trial of clonzepam.

Clonazepam was preferred over other benzodiazepines because of its relatively longer half life and lesser addiction potential (7). Possible mechanism behind clonazepam beneficial effect could lie in its serotonergic properties, and that it may enhance serotonergic transmission (8).

Tanvir Singh, MD

Syed Imam, MD

Tanvir Singh is Assistant Professor and Syed Imam is Resident in Dept. of Psychiatry at University Toledo Medical Center, Toledo, Ohio, USA.



First Published April 2007

Copyright  © Priory Lodge Education Limited 2007

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