The Relationship Between Drug-Induced Psychosis & Schizophrenia

Psychotic episodes are distressing experiences that often result from mental health disorders such as schizophrenia. However, mental illness is not the only potential cause of psychosis. Certain types of substance use can also prompt the onset of psychotic symptoms.

Many researchers have explored the possible relationship between drug-induced psychosis and psychotic episodes that are related to schizophrenia. The goals of this research include better understanding the causes and effects of psychosis, as well as identifying optimal treatment approaches for individuals whose lives have been disrupted by psychotic episodes.

What Is Psychosis?

Psychosis is characterized by an inability to accurately perceive one’s environment. This condition can also impair a person’s ability to effectively communicate with other people.

In a report on the website of the National Library of Medicine, Jordan Calabrese of Aventura Hospital and Medical Center and Yasir Al Khalili of Virginia Commonwealth University defined psychosis as “a constellation of symptoms resulting in a loss of contact with reality.”

Calabrese’s and Al Khalili’s report also provided the following information about psychosis:

• Researchers estimate that 1.5%-3.5% of people will meet the clinical criteria for a diagnosis of a psychotic disorder. However, many more people are likely to experience at least one symptom of psychosis over the course of their lifetime.
• Psychosis has been associated with a variety of psychiatric, neuropsychiatric, neurologic, neurodevelopmental, and medical conditions.
• Psychosis may be related to abnormalities of temporal grey matter, as well as altered levels of several neurotransmitters, including dopamine, GABA, glutamate, and acetylcholine.
• Psychosis can be a co-occurring aspect of mood disorders and substance use disorders.
• For men, psychosis symptoms typically first occur between the teens and the mid-20s.
• Women usually first experience symptoms between their teens and their late 20s.
• Occurrences of psychosis are extremely rare among children.

Schizophrenia & Psychosis

Among the several mental illnesses that have been linked to psychosis, the most common psychotic disorder is schizophrenia.

According to the World Health Organization (WHO), schizophrenia affects about 24 million people, or about 0.32% of the global population. The National Alliance on Mental Illness (NAMI) estimates that about 1.5 million people in the United States have schizophrenia.

As defined in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), people who develop schizophrenia may experience five types of psychotic symptoms:

• Hallucinations – These are false perceptions that involve one or more of the five senses. The most common types of hallucinations are auditory (hearing voices or sounds that do not exist) and visual (seeing people, objects, or light patterns that are not really there).
• Delusions – These are firmly held beliefs that are either easily disproven or that have no basis in reality. A person who struggles with delusions may believe that they have magical powers, are being persecuted by a government agency, or are in a loving relationship with a famous person that they have never met.
• Disorganized speech – This may involve rapidly jumping from topic to topic with no logical connection or progression, responding to questions with unrelated statements, or using nonsense words or sounds that convey no meaning to the listener.
• Grossly disorganized or catatonic behavior – This type of symptom is related to how a person acts or moves. Examples can include dressing in a bizarre fashion, exhibiting unpredictable aggression or agitation, behaving in a childlike manner, and holding their body in awkward positions for extended periods of time.
• Negative symptoms – People who experience negative symptoms may speak in a flat or monotone manner, fail to use facial expressions, have a marked lack of motivation, and show no interest in interacting with others or even leaving the house.

To meet the diagnostic criteria for schizophrenia as established in the DSM-5, a person must have at least two of the five symptom types listed above – and at least one of their symptoms must be hallucinations, delusions, or disorganized speech.

Drug-Induced Psychosis

In addition to schizophrenia and other mental health disorders, the abuse of certain substances can also trigger psychotic episodes. A study in the January 2020 edition of the journal Child and Adolescent Psychiatric Clinics of North America reported that the following substances have the strongest association with drug-induced psychosis:

• Cannabinoids including marijuana, hash oil, wax, and edibles
• Stimulants including cocaine, amphetamine, and methamphetamine
• Hallucinogens such as LSD
• So-called club drugs or designer drugs, a category that includes substances such as MDMA (ecstasy or molly), K2, bath salts, and flakka

It is important to understand that drug-induced psychosis, which may also be referred to as substance-induced psychosis, is far more serious and potentially dangerous than what typically occurs when a person gets drunk or high. Also, the symptoms of drug-induced psychosis will persist after the intoxicating effects of the substance have worn off.

Drug-induced psychosis shares many features with schizophrenia-related psychosis. These similarities can make it difficult for healthcare providers to make accurate diagnoses. However, there are also a few key differences between psychosis that results from drug abuse and psychosis that is symptomatic of schizophrenia. For example:

• As we described in the previous section, people who have schizophrenia may develop five types of symptoms.
• Most cases of drug-induced psychosis only involve two of these symptoms: hallucinations and delusions.
• People who are in the midst of a drug-induced psychotic episode may also experience confusion, disorientation, paranoia, panic attacks, and other symptoms.

Another significant difference between these two types of psychosis is the duration of the episodes:

• Drug-induced psychotic episodes usually last from a few hours to a few weeks.
• To be accurately diagnosed with schizophrenia, a person must have symptoms of psychosis for a minimum of six months.

This is not meant to imply that drug-induced psychosis is not a serious, potentially devastating concern. A person who experiences a drug-induced psychotic episode may be at risk for significant physical and psychological damage. Also, as we will discuss in the next section, drug-induced psychosis may be a risk factor for developing schizophrenia and certain other mental illnesses.

The Link Between Drug-Induced Psychosis & Schizophrenia

A November 2017 study in The American Journal of Psychiatry found that many people who experience drug-induced psychosis are diagnosed with schizophrenia or bipolar disorder later in life.

This study involved a review of the 6,788 cases of drug-induced psychosis that were documented in the Danish Civil Registration System and the Psychiatric Central Research Register between 1994-2014. None of the cases that were analyzed for this study involved people who had previously been diagnosed with schizophrenia or bipolar disorder.

The research team’s findings included the following:

• 2% of people who had a drug-induced psychotic episode were later diagnosed with either schizophrenia or bipolar disorder.
• Cannabis-induced psychosis was the strongest predictor of an eventual mental health diagnosis. 47.7% of those who had this type of drug-induced psychosis converted to either bipolar disorder or schizophrenia.
• About 50% of people who converted from drug-induced psychosis to schizophrenia did so within 3.1 years of their initial episode.
• About 50% of conversions from drug-induced psychosis to bipolar disorder took place within 4.4 years of the initial drug-induced experience.
• People who had a drug-induced psychotic episode between the ages of 16-25 had the highest risk of converting to schizophrenia or bipolar disorder.
• People who engaged in self-harm after their drug-induced psychotic episode had a significantly higher risk of later being diagnosed with schizophrenia or bipolar disorder.

The findings of the Danish study were supported by a meta-analysis that was published in the April 2020 edition of the journal Schizophrenia Bulletin. This review of drug-induced psychosis and schizophrenia involved 50 studies with more than 40,000 subjects. The studies the team reviewed had been conducted in England, Denmark, the United States, India, and 21 other countries.

The team that conducted this meta-analysis was led by Benjamin Murrie of St George Hospital and Sutherland Hospital in Kogarah, Australia. Their findings included the following:

• 25% of the studies’ subjects who had a drug-induced psychotic episode eventually transitioned to schizophrenia.
• The highest rates of transition to schizophrenia involved subjects who had drug-induced psychotic episodes involving cannabis (34%) and hallucinogens (26%).
• Rates of transition from drug-induced psychosis to schizophrenia were slightly lower among older subjects.

Neither the Danish team nor the researchers from Australia claimed that drug-induced psychosis causes people to develop schizophrenia or bipolar disorder.

For example, the Danish group noted that several people in their study had previously been diagnosed with substance use disorders, eating disorders, depressive disorders, and other mental health concerns – and these people were more likely to eventually be diagnosed with schizophrenia or bipolar disorder.

In other words, in some cases, people who have drug-induced psychotic episodes may already be living with undiagnosed schizophrenia. In other cases, drug-induced psychosis may be the factor that prompts the onset of schizophrenia symptoms among people who already have a genetic predisposition for this disorder.

Regardless of their history with drug-induced psychosis, anyone who develops schizophrenia can benefit from personalized care provided by a reputable provider. When a person with schizophrenia receives the treatment services that align most closely with their unique needs, they can achieve improved health, greater capacity for independent living, and higher overall quality of life.