Hallucinogen persisting perception disorder (HPPD) is a long-term condition caused by taking hallucinogens. People with this condition experience perceptual (usually visual) distortions even after the "trip" is over and the drug and its metabolites have left the body. Under some definitions it is a requirement for diagnosis that the distortions affect the person's ability to function normally. It is a DSM-IV diagnosis with diagnostic code 292.89.

Overview

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HPPD is different from a drug-induced psychosis in that a person with HPPD is fully aware that the distortions are not real (i.e. do not reflect any external reality that can be experienced by other people). Still, the distortions experienced by a person with HPPD can be powerful and may provoke anxiety. Some patients with HPPD are troubled with feelings of guilt and regret. In particular, HPPD is very often comorbid with Depersonalization disorder, which can also be caused by drug use.

Cases of HPPD can be divided in two categories: The cases in which the perceptual distortions are present all the time (sometimes even when the person in question has his/her eyes closed, in the case of visual distortions) and the cases where the person experiences the distortions in the form of "flashbacks" of short duration once in a while.

Most case reports seem to involve LSD or ecstasy, perhaps reflecting the relative popularity of those drugs. In some cases the person in question took the drug(s) several times without problems, with the HPPD suddenly occurring after a particular drug experience. In other cases, the person reports the condition worsening with repeated use of a drug. Sometimes the drug user may initially dismiss the symptoms as "after-effects" of the trip until realizing their persistent nature. Finally, in some cases HPPD occur after taking the drug just once or a few times. HPPD may occur some time after the drug experience - in some reports, even after several months.

The mechanism underlying HPPD is not known. The disorder seems to occur only in a minority of drug users. It is not known exactly what types of drug may cause it, or if the disorder is related to the presence of contaminants in the drugs taken.

Symptoms

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HPPD includes many types of distortions. Under most definitions, it is a requirement that the distortions have some resemblance to the distortions experienced by the person while under the influence of the hallucinogen in question.

Some visual disturbances are normal, and are experienced by many people who have never taken drugs. These include floaters (black/dark objects that appear to be floating on the eyes, particularly visible when looking at the bright sky or on a white wall). Likewise, bright lights in an otherwise dark environment may generate trails and halos. Most people don't notice these effects, because they are so used to them. A person fearful of having acquired HPPD may be much more conscious about any visual disturbance, including those that are normal.

The visual form of HPPD may include one or more of the following symptoms: Halos around objects, trails after objects (usually after bright objects on a dark background or vice versa), difficulty in distinguishing between colors, colors of objects changing while looking at them, geometric hallucinations (sometimes called pseudohallucinations, due to the fact that the person recognizes that the hallucinations are not "real"), illusions that objects are moving even when they are not, static (like static from a television superimposed on what the person is seeing) also called aeropsia or visual snow, objects changing sizes while looking at them and floaters.

Treatment

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HPPD ceases on its own in many cases. It is generally advised that the person discontinues all drugs (even those that may not appear to be related to HPPD). There are indications that continued drug use can worsen the condition. The recovery may take considerable time (from several days to several years) and may either be gradual or sudden.

There is currently no known cure of HPPD, however, some medications such as benzodiazepines such as Valium or Xanax, and particularly the anticonvulsant drug clonazepam/Klonopin appear to be helpful. People with HPPD can learn to habituate to the condition and be able to lead otherwise normal lives. Some medications (such as antipsychotics) seem to worsen HPPD symptoms in some people but may lessen them in others. Treatment of HPPD should, if possible, be undertaken by a psychiatrist with experience in treating the disorder.

External links

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• A comprehensive source on HPPD. Has a large section with references to journal articles
• Erowid's FAQ on HPPD

Psychedelics, dissociatives and deliriants | Mental illness diagnosis by DSM and ICD

Hallucinogen persisting perception disorder | Hallucinogen persisting perception disorder