- Describe hallucinogens and how they affect the brain and behavior
- Describe the diagnostic features, development, and risk factors of hallucinogen-related disorders, including phencyclidine, inhalant use disorder, and other hallucinogens
A hallucinogen is one of a class of drugs that results in profound alterations in sensory and perceptual experiences. In some cases, users experience vivid visual hallucinations. Common hallucinogens include psilocybin (shrooms), mescaline (peyote), and LSD. These substances also commonly cause hallucinations of body sensations (e.g., feeling as if you are a giant) and a skewed perception of the passage of time.
Leo Hollister’s five criteria for establishing that a drug is hallucinogenic are as follows:
- in proportion to other effects, changes in thought, perception, and mood should predominate;
- intellectual or memory impairment should be minimal;
- stupor, narcosis, or excessive stimulation should not be an integral effect;
- autonomic nervous system side effects should be minimal; and
- addictive craving should be absent.
As a group, hallucinogens are incredibly varied in terms of the neurotransmitter systems they affect. Mescaline and LSD are serotonin agonists, and PCP (angel dust) and ketamine (an animal anesthetic) act as antagonists of the NMDA glutamate receptor. In general, these drugs are not thought to possess the same sort of abuse potential as other classes of drugs discussed in this section.
Some hallucinogens are extracted from plants or mushrooms, and some are synthetic (human-made). Historically, people have used hallucinogens for religious or healing rituals. More recently, people report using these drugs for social or recreational purposes, including to have fun, deal with stress, have spiritual experiences, or just to feel different.
Common classic hallucinogens include the following:
- LSD (D-lysergic acid diethylamide) is one of the most powerful mind-altering chemicals. It is a clear or white odorless material made from lysergic acid, which is found in a fungus that grows on rye and other grains. LSD has many other street names, including acid, blotter acid, dots, and mellow yellow.
- Psilocybin (4-phosphoryloxy-N, N-dimethyltryptamine) comes from certain types of mushrooms found in tropical and subtropical regions of South America, Mexico, and the United States. Some common names for psilocybin include little smoke, magic mushrooms, and shrooms.
- Peyote (mescaline) is a small, spineless cactus with mescaline as its main component. Peyote can also be synthetic. Common names for peyote are buttons, cactus, and mesc.
- DMT (N, N-dimethyltryptamine) is a powerful chemical found naturally in some Amazonian plants. Ayahuasca is a tea made from such plants, and when taken in this form, it is also known as hoasca, aya, and yagé. People can also make DMT in a lab. Synthetic DMT usually takes the form of a white crystalline powder that is smoked. A popular name for synthetic DMT is Dimitri.
- 251-NBOMe is a synthetic hallucinogen with similarities both to LSD and MDMA but that is much more potent. Developed for use in brain research, when sold on the street, it is sometimes called N Bomb or 251.
- Methylenedioxymethamphetamine (MDMA), commonly known as ecstasy (E) or molly, is a psychoactive drug primarily used for recreational purposes. The desired effects include altered sensations and increased energy, empathy and pleasure. When taken by mouth, effects begin in 30 to 45 minutes and last three to six hours. It is an amphetamine, but often classified with hallucinogens for its hallucinogenic effects. Adverse effects include addiction, memory problems, paranoia, difficulty sleeping, grinding of the teeth, blurred vision, sweating, and a rapid heartbeat. Deaths have been reported due to increased body temperature and dehydration. Following its use, people often feel depressed and tired. MDMA acts primarily by increasing the activity of the neurotransmitters serotonin, dopamine, and noradrenaline in parts of the brain.
Common examples of dissociative drugs include the following:
- PCP (Phencyclidine) was developed in the 1950s as a general anesthetic for surgery, but it is no longer used for this purpose due to serious side effects. PCP can be found in a variety of forms, including tablets or capsules; however, liquid and white crystal powder are the most common forms. PCP has various slang names, such as angel dust, hog, love boat, and peace pill.
- Ketamine is used as a surgery anesthetic for humans and animals. Much of the ketamine sold on the streets comes from veterinary offices. It mostly sells as a powder or as pills, but it also available as an injectable liquid. Ketamine is snorted or sometimes added to drinks as a date-rape drug. Slang names for ketamine include Special K and Cat Valium.
- Dextromethorphan (DXM) is a cough suppressant and mucus-clearing ingredient in some over-the-counter cold and cough medicines (syrups, tablets, and gel capsules). Robo is a common slang name for DXM.
- Salvia (Salvia divinorum) is a plant common to southern Mexico and Central and South America. Salvia is typically ingested by chewing fresh leaves or by drinking their extracted juices. The dried leaves of salvia can also be smoked or vaporized and inhaled. Popular names for salvia are diviner’s sage, Maria Pastora, Sally-D, and magic mint.
Hallucinogen-related disorders in the DSM-5 include all of the following:
- phencyclidine use disorder
- other hallucinogen use disorder
- phencyclidine intoxication
- other hallucinogen intoxication
- hallucinogen persisting perception disorder
- other phencyclidine-induced disorders
- other hallucinogen-induced disorders
- unspecified phencyclidine-related disorder
- unspecified hallucinogen-related disorder
Similar to the other categories of disorders we have learned about, the hallucinogen-use disorders describe a dependency on the drug, while intoxication refers to changes in behavior and psychology during or immediately following the use of the drug. These categories do not have withdrawal disorders.
Phencyclidine or phenylcyclohexyl piperidine (PCP), also known as angel dust, is a drug used for its mind-altering effects. PCP may cause hallucinations, distorted perceptions of sounds, and violent behavior. As a recreational drug, it is typically smoked, but may be taken by mouth, snorted, or injected. It may also be mixed with cannabis or tobacco.
Adverse effects may include seizures, coma, addiction, and an increased risk of suicide. Flashbacks may occur despite stopping usage. PCP is most commonly used in the United States. While usage peaked in the United States in the 1970s, between 2005 and 2011, an increase in visits to emergency departments as a result of the drug occurred. As of 2017 in the United States, about 1% of people in grade 12 reported using PCP in the prior year while 2.9% of those over the age of 25 reported using it at some point in their lives.
Phencyclidine intoxication occurs when a person’s mental capacity to recognize reality, communicate, and relate to others is impaired, thus interfering with the capacity to deal with life demands.
Other Hallucinogen-Use Disorders
Other hallucinogen-use disorders involve a problematic pattern of hallucinogen use (other than PCP/phencyclidine), including LSD (acid), ecstasy (MDMA), ketamine, mushrooms, peyote, etc.
As of 2017, about 10% of people in the United States have used LSD at some point in their lives, while 0.7% have used it in the last year. It was most popular in the 1960s to 1980s. The use of LSD among U.S. adults increased 56.4% from 2015 to 2018. LSD is typically either swallowed or held under the tongue.
Hallucinogen Persisting Perception Disorder
Hallucinogen persisting perception disorder (HPPD) is a chronic disorder in which a person has non-psychotic flashbacks of visual hallucinations or distortions experienced during a previous hallucinogenic drug experience, usually lacking the same feelings of mental intoxication experienced before. Hallucinations are usually not intense or impairing and consist of visual snow, trails and after images (palinopsia), light fractals on flat surfaces, intensified colors, or other psychedelic visuals. To be diagnosed, the disorder must cause distress or impairment in work or everyday life. The flashbacks may be continuous or just occasional. Symptoms often get worse when they’re focused on.
The prevalence of HPPD was unknown as of 2018. Estimates in the 1960s and 1970s were around one in 20 for intermittent HPPD among regular users of hallucinogens. It is not clear how common chronic HPPD may be, but one estimate in the 1990s was that one in 50,000 regular users might have chronic hallucinations.
The only certain cause for HPPD is the prior use of hallucinogens. Some evidence points to phenethylamines carrying a slightly greater risk than lysergamides or tryptamines. Some sort of disinhibition of visual processing may be involved. It has been suggested MDMA (ecstasy) use with other drugs is linked to the development of HPPD.
Diagnostic Criteria for Phencyclidine and Other Hallucinogen Use Disorder
A. A problematic pattern of phencyclidine [or other hallucinogen] use leading to clinically significant impairment or distress, as manifested by at least two of the following, occurring within a 12-month period:
- Phencyclidine [or other hallucinogen] is often taken in larger amounts or over a longer period than was intended.
- There is a persistent desire or unsuccessful efforts to cut down or control phencyclidine (or other hallucinogen) use.
- A great deal of time is spent in activities necessary to obtain phencyclidine (or other hallucinogen), use phencyclidine, or recover from its effects.
- Craving, or a strong desire or urge to use phencyclidine (or other hallucinogen).
- Recurrent phencyclidine (or other hallucinogen) use resulting in a failure to fulfill major role obligations at work, school, or home (e.g., repeated absences from work or poor performance related to phencyclidine use; phencyclidine-related absences, suspensions, or expulsions from school; or neglect of children or household).
- Continued phencyclidine (or other hallucinogen) use despite having persistent or recurrent social or interpersonal problems caused or exacerbated by the effects of phencyclidine (e.g., arguments with a spouse about consequences of intoxication or physical fights).
- Important social, occupational, or recreational activities are given up or reduced because of phencyclidine (or other hallucinogen) use.
- Recurrent phencyclidine (or other hallucinogen) use in situations in which it is physically hazardous (e.g., driving an automobile or operating a machine when impaired by a phencyclidine).
- Phencyclidine (or other hallucinogen) use is continued despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by phencyclidine.
- Tolerance, as defined by either of the following:
- a. A need for markedly increased amounts of phencyclidine to achieve intoxication or desired effect.
- b. A markedly diminished effect with continued use of the same amount of phencyclidine.
PCP was initially made in 1926 and brought to market as an anesthetic medication in the 1950s. Its anesthetic effects were discovered by Victor Maddox, a chemist at Parke-Davis in Michigan, while investigating synthetic analgesic agents. It was approved for use as an investigational drug under the brand names Sernyl and Sernylan in the 1950s as an anesthetic, but because of its long terminal half-life and adverse side-effects, such as hallucinations, mania, delirium, and disorientation, it was removed from the market in 1965 and limited to veterinary use, until that was disallowed in 1978.
There are no FDA-approved medications to treat addiction to hallucinogen addiction. While behavioral treatments can be helpful for patients with a variety of addictions, scientists need more research to find out if behavioral therapies are effective for addiction to hallucinogens. For HPDD, some antidepressant and antipsychotic medications can be used to improve mood and treat psychosis. Behavioral therapies can be used to help people cope with fear or confusion associated with visual disturbances. Management of PCP intoxication mostly consists of supportive care—controlling breathing, circulation, and body temperature—and, in the early stages, treating psychiatric symptoms. Benzodiazepines, such as lorazepam, are the drugs of choice to control agitation and seizures (when present).
Key Takeaways: Hallucinogen-Related Disorders
Inhalants are a broad range of household and industrial chemicals whose volatile vapors or pressurized gases can be concentrated and breathed in via the nose or mouth to produce intoxication in a manner not intended by the manufacturer. Inhalants are inhaled at room temperature through volatilization (in the case of gasoline or acetone) or from a pressurized container (e.g., nitrous oxide or butane), and do not include drugs that are sniffed after burning or heating. For example, amyl nitrite (poppers), nitrous oxide, and toluene—a solvent widely used in contact cement, permanent markers, and certain types of glue—are considered inhalants, but smoking tobacco, cannabis, and crack are not, even though these drugs are inhaled as smoke.
While a small number of inhalants are prescribed by medical professionals and used for medical purposes, as in the case of inhaled anesthetics and nitrous oxide (an anxiolytic and pain relief agent prescribed by dentists), inhalants typically refer to the use of household and industrial propellants, glues, fuels, and other products in a manner not intended by the manufacturer to produce intoxication or other psychoactive effects. These products are used as recreational drugs for their intoxicating effect. According to a 1995 report by the National Institute on Drug Abuse, the most serious inhalant abuse occurs among homeless children and teens who “live on the streets completely without family ties.” Inhalants are the only substances used more by younger teens than by older teens. The practices are known colloquially as “sniffing”, “huffing,” or “bagging.”
Inhalant disorders described in the DSM-5 include inhalant use disorder, inhalant intoxication, other inhalant-induced disorders, and unspecified inhalant-related disorder. Inhalant use disorder is defined as a problematic pattern of use of a hydrocarbon-based inhalant substance leading to clinically significant impairment or distress.
Inhalant intoxication occurs frequently during inhalant use disorder but also may occur among individuals whose use does not meet the criteria for inhalant use disorder. Inhalant intoxication is identified as the following:
A. Recent intended or unintended short-term, high-dose exposure to inhalant substances, including volatile hydrocarbons such as toluene or gasoline.
B. Clinically significant problematic behavioral or psychological changes (e.g., belligerence, assaultiveness, apathy, and impaired judgment) that developed during, or shortly after, exposure to inhalants.
C. Two (or more) of the following signs or symptoms developing during, or shortly after, inhalant use or exposure:
- slurred speech
- unsteady guilt
- depressed reflexes
- psychomotor retardation
- generalized muscle weakness
- blurred vision or diplopia
- stupor or coma
The effects of inhalants range from an alcohol-like intoxication and intense euphoria to vivid hallucinations, depending on the substance and the dose. Some inhalant users are injured due to the harmful effects of the solvents or gases or due to other chemicals used in the products that they are inhaling. In some cases, users have died from hypoxia (lack of oxygen), pneumonia, cardiac failure or arrest, or aspiration of vomit. Brain damage is typically seen with chronic long-term use of solvents as opposed to short-term exposure.
251-NBOMe: a synthetic hallucinogen with similarities both to LSD and MDMA but that is much more potent
DMT: a powerful chemical found naturally in some Amazonian plants
DXM: a cough suppressant and mucus-clearing ingredient in some over-the-counter cold and cough medicines
hallucinogen: one of a class of drugs that results in profound alterations in sensory and perceptual experiences, often with vivid hallucinations
HPPD: a chronic disorder in which a person has non-psychotic flashbacks of visual hallucinations or distortions experienced during a previous hallucinogenic drug experience, usually lacking the same feelings of mental intoxication experienced before
inhalants: a broad range of household and industrial chemicals whose volatile vapors or pressurized gases can be concentrated and breathed in via the nose or mouth to produce intoxication
inhalant intoxication: occurs frequently during inhalant use disorder but also may occur among individuals whose use does not meet criteria for inhalant use disorder
inhalant use disorder: a problematic pattern of use of a hydrocarbon-based inhalant substance leading to clinically significant impairment or distress
ketamine: used as a surgery anesthetic for humans and animals
LSD: is one of the most powerful mind-altering chemicals and it is a clear or white odorless material made from lysergic acid, which is found in a fungus that grows on rye and other grains
MDMA: commonly known as ecstasy (E) or molly, is a psychoactive drug primarily used for recreational purposes and the desired effects include altered sensations, increased energy, and empathy as well as pleasure
peyote: a small, spineless cactus with mescaline as its main ingredient and can also be synthetic
PCP: also known as angel dust, is a drug used for its mind-altering effects and may cause hallucinations, distorted perceptions of sounds, and violent behavior
salvia: a plant common to southern Mexico and Central and South America and is typically ingested by chewing fresh leaves or by drinking their extracted juices