Hallucinogen persisting perception disorder, also referred to as HPPD, is an uncommon condition caused by hallucinogens. Research on the disorder is limited to small studies and case reports. Its prevalence is unknown, but some experts estimate 4 percent of people who use hallucinogens develop HPPD.
The disorder is different from experiencing flashbacks after the effects of hallucinogens wear off. Flashbacks are common side effects of hallucinogen misuse. They typically end days after a person stops using hallucinogens.
HPPD is a persistent, recurring disorder that distorts a person’s visual perception. It can occur months or years after hallucinogen abuse. The symptoms, which aren’t linked to another disorder, may persist for months or years. In some cases, medical care can relieve symptoms of HPPD, but diagnosing the disorder can be difficult.
Hallucinogen use is the primary cause of HPPD. LSD abuse appears to be the most common cause of the disorder. Despite its similarity to LSD, psilocybin has only caused one documented case of HPPD, according to a 2012 review in the journal Therapeutic Advances in Psychopharmacology. Psilocybin is the psychoactive drug in magic mushrooms.
The person who developed psilocybin-related HPPD combined the drug with marijuana — a drug that has some hallucinogenic properties. Marijuana and heavy alcohol use have triggered HPPD in some people who have a history of hallucinogen use.
Reports of drugs other than LSD causing HPPD are rare, but the following drugs have reportedly caused the condition:
Heavy hallucinogen use does not seem to be associated with an increased risk of HPPD. A study of 500 members of the Native American Church who had taken peyote at least 100 times revealed zero incidences of HPPD.
Additionally, marijuana is the most commonly used drug in the United States, but reports of HPPD among marijuana users are uncommon.
Experts do not know the biological cause of HPPD. They believe hallucinogens may inhibit systems in the brain that constantly filter signals that affect our perception. The brains of people with HPPD may be unable to filter unnecessary signals, causing visual distortions, according to a 2018 article in the journal Brain Sciences.
Case reports by experts studying HPPD have revealed a large variety of symptoms. Some authoritative organizations refer to recurring flashbacks as HPPD. Others use strict criteria to differentiate flashbacks from HPPD.
No standard set of symptoms for HPPD exists, but common symptoms of the disorder include:
These symptoms may occur immediately after hallucinogen use and persist continuously. Or they may develop more than a year after hallucinogen use, fade and recur over time. In general, alcohol and other drugs can worsen symptoms of HPPD.
To be diagnosed with HPPD, a person can’t experience symptoms associated with the disorder before using hallucinogens. The disorder has to result from drug use. Lingering effects of a drug or symptoms of hallucinogen withdrawal that fade within days do not fit the criteria for HPPD.
The American Psychiatric Association clearly defines HPPD in its diagnostic manual. To receive an HPPD diagnosis, individuals must:
Some researchers define the disorder differently. In an attempt to help health professionals differentiate flashbacks from HPPD, researchers writing in The Israel Journal of Psychiatry and Related Sciences defined two types of HPPD.
The flashback type, also referred to as HPPD I, is a benign or harmless condition. People with HPPD I experience flashbacks, visual distortions or changes to how they think. They don’t feel anxious or afraid. Some people may enjoy the experience. Those with HPPD I rarely seek treatment.
Unlike people with HPPD II, people with HPPD I aren’t impaired. The flashbacks are usually brief. They recur over time but eventually resolve without treatment. Flashbacks may be triggered by an event or experience, or they may occur spontaneously.
HPPD II aligns with the APA’s criteria for hallucinogen persisting perception disorder. Compared to people with HPPD I, those with HPPD II feel more intense symptoms. It’s a chronic condition that recurs and may be either spontaneous or caused by triggers. HPPD II causes significant impairment and distress.
Individuals with HPPD II often feel debilitated and seek psychiatric treatment for the condition. They usually stop using alcohol and other drugs. A general misunderstanding or lack of awareness of HPPD II among doctors may lead to misdiagnosis or ineffective treatment.
Medications are the primary treatment for HPPD. Prescription drugs don’t cure the disease, but they may help alleviate some symptoms.
Comprehensive studies on medications aren’t available, but researchers have analyzed common treatments used in case reports or small studies, according to the latest literature review published in the journal Drug and Alcohol Dependence.
Benzodiazepines, such as Xanax (alprazolam) or Klonopin (clonazepam), appear to be the most effective treatment. Less potent benzos, such as Ativan (lorazepam), aren’t as effective. However, benzos have a high potential for abuse. Other medications may be more appropriate for people with a history of addiction.
Medications that have had mixed success in case reports of people treated for HPPD include:
These medications may not be effective for everyone. In some cases, they have caused worsening symptoms. Doctors may try different types of medications until a successful treatment is found.
Behavioral or talk therapy may help individuals cope with complications of HPPD, such as co-occurring anxiety or depression. Therapy can also help individuals function or overcome impairment. However, it’s unlikely to directly relieve symptoms of HPPD.
HPPD is a debilitating disease that isn’t fully understood. It is believed to be a rare side effect of hallucinogen use. The most effective treatment for HPPD remains unknown, but medications and therapy have helped some people cope with symptoms.
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