graphic of brain on marijuana with key to represent psychosis
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When we think about chronic substance use and substance use disorder (SUD) most of us understand the long-term use of addictive substances can lead to significant physical, emotional, and psychological consequences.

But can drug use cause mental health disorders aside from substance use disorder?

In some cases, the answer is yes – but it’s complicated.

Evidence does show a relationship between the disordered use of substances and the subsequent onset of psychotic symptoms. Research conducted over the past two decades indicates the use of illicit substances can cause temporary psychotic symptoms during acute intoxication, and may also lead to symptoms similar to primary psychotic disorders. Sometimes, these psychotic episodes may lead to the development psychotic disorders.

Substances known to induce psychotic symptoms include:

  • Cannabinoids
  • Cocaine
  • Methamphetamines
  • Hallucinogens

When psychotic symptoms appear in a patient who also uses one of these illicit drugs, clinicians face a challenge:

How do we distinguish between a substance-induced psychosis, a primary psychotic disorder, or a psychotic disorder with co-occurring/comorbid substance use?

That’s one of the questions researchers asked in a peer reviewed journal article published in 2021 called “Substance-Induced Psychoses: An Updated Literature Review.” In this article, we’ll discuss the findings in this paper, and address the problems associated with untangling the complex set of factors surrounding the relationship between substance use and psychosis, psychotic symptoms, and psychotic disorders.

What is Substance-Induced Psychosis?

The Diagnostic and Statistical Manual of Mental Disorder, Fifth Edition (DSM-5) defines the substance-induced psychotic disorder as follows:

“A psychiatric disease featured by delusions and/or hallucination during or soon after substance intoxication or withdrawal.”

To receive a diagnosis for substance-induced psychosis, the DSM-5 indicates a patient must meet the following criteria:

A. Presence of one or both of the following symptoms:

    • Delusions
    • Hallucinations

B. Evidence from patient history, examination, or laboratory result that either:

    • The symptoms in Criterion A developed during, or within a month of, substance intoxication or withdrawal
    • Medication is etiologically related (a cause) of the symptoms

D. Symptoms are not better explained by a psychotic disorder that is not substance-induced.

E. The symptoms do not occur exclusively during delirium.

F. Symptoms cause clinically significant distress or impairment in social, work, or other areas of functioning.

Those criteria are straightforward, and relatively easy for a non-medical or mental health professional to  understand: substance-induced psychosis happens when psychotic symptoms appear after substance use, and there’s not a better explanation for the symptoms.

Experts divide the symptoms mentioned above – delusions and hallucinations – into two categories: positive symptoms, defined by the presence of atypical thoughts/behaviors, and negative symptoms, defined by the absence of typical moods, thoughts, or behaviors.

Positive symptoms include:

  • Unusual/new/unverifiable beliefs
  • Delusions of persecution, such as “they’re out to get me”
  • Hallucinations, i.e., seeing or hearing things that aren’t there

Negative symptoms include:

  • Disrupted thinking, displayed by absence of speech or incoherent speech
  • Decreased motivation to engage in typical activity
  • Decreased emotional expression

Other symptoms associated with psychosis include:

  • Insomnia
  • Aggression
  • Agitation
  • Mood swings
  • Suicidal ideation

This brings us to the central challenge behind understanding substance-induced psychosis and its relationship to psychotic disorders: diagnosis. Identifying these symptoms is not a challenge for a trained professional. However, using the symptoms to arrive at an accurate diagnosis is very challenging, for a variety of reasons.

Drug-Induced Psychosis and Psychotic Disorders: What’s the Difference?

Let’s back up for a moment and ensure we’re making one thing clear: the symptoms above are also the symptoms of mental health disorders with psychotic features, such as schizophrenia, delusional disorder, and others.

That’s where the confusion and challenge appear and make diagnosis difficult. In mental health care – in all health care, actually – an accurate diagnosis is the first step in determining an appropriate treatment plan. Treating a person for something they don’t have can create problems, and not treating a person for something they do have also creates problems: that’s the primary dilemma we face.

Theoretically speaking, the thing that distinguishes drug-induced psychosis and the onset of a psychotic disorder is timing. For drug-induced psychosis, the symptoms appear shortly after ingesting a drug or during withdrawal following chronic drug use, and resolve – i.e., disappear – after a period of abstinence.

The body processes and eliminates the drug, and the symptoms go away – simple. If the symptoms persist after a period of abstinence, then they must be the signs of a psychotic disorder, rather than drug-induced psychosis – also simple.

However, when we translate theory into practice, things get complex.

Complicating factors include:

  • People at high risk of developing psychosis are more likely to use substances of misuse and disordered use than people at low risk of developing psychosis
  • Among people who use drugs, polysubstance misuse – using more than one drug – is a common behavior
  • Various drugs can have various effects that persist for different periods of time
    • Drug related hallucinations may appear long after discontinuation
  • People who use drugs don’t always stop using drugs after their first psychotic episode

Here’s what these complicating factors mean for diagnosis: timing or chronology is not always sufficient to differentiate between substance-induced psychosis and the onset of a psychotic disorder.

How Do We Decide What’s Substance-Induced Psychosis and What Isn’t?

That’s where the results of the study we introduce above can help. The researchers examined the results of 72 peer-reviewed scientific articles to identify factors that can help clinicians distinguish between the onset of a psychotic disorder and drug-induced psychosis.

We’ll review the relationship of each type of substance we mention in the introduction of this article to psychosis, then summarize the conclusions the research team reached.

Cannabis/Synthetic Cannabinoids:

  • Prevalence of use: 50.3% (128 million) of adults 18+ report using cannabis during their lifetime
  • Prevalence of psychotic symptoms among cannabis users: 0.87% – 10.6%
  • Studies show cannabis use increases risk of schizophrenia, a disorder which can have psychotic symptoms
  • Frequency and severity of use affects presence of psychotic symptoms: high frequency and greater severity associated with increased risk of psychotic symptoms
  • Among cannabis users who experience cannabis-induced psychotic symptoms: 47% showed subsequent conversion to schizophrenia
  • One study showed that cannabis users who completely abstained from cannabis use after one psychotic episode did not relapse to psychiatric illness
  • Preliminary studies on synthetic cannabinoids (e.g. spice) show patients with pre-existing psychiatric disorders may develop symptoms of psychosis
  • Further research and long-term studies are needed to confirm the relationship of synthetic cannabinoids and psychosis

Cocaine:

  • Prevalence of use: 16.5% (42.1 million) of adults 18+ report cocaine use during their lifetime
  • Prevalence of psychotic symptoms among cocaine users: 29% – 86.5%
  • A study on people with cocaine use disorder reported:
    • 52% experienced psychotic symptoms
    • 90% experienced paranoid delusions
    • 96% experienced hallucinations
    • 29% developed behavior abnormalities
  • Frequency of use, severity of use, and early age at first use impacted presence of psychotic symptoms: high frequency, greater severity, and earlier use was associated with increased risk of psychotic symptoms
  • In most cases, psychotic symptoms related to cocaine use are transient, and fade after discontinuation of use
  • Treatment facilities the gradual fading of symptoms
  • Chronic use may cause permanent neurological problems aside from psychosis/psychotic symptoms/psychotic disorders

Methamphetamines:

  • Prevalence of use: 5.9% (16.5 million) of adults 18+ report methamphetamine use during their lifetime
  • Prevalence of psychotic symptoms among methamphetamine users: 11.3% – 36.5%
  • Among people with methamphetamine use disorder: 22.1% – 42.7%
  • In a meta-analysis of 94 studies on people with methamphetamine-induced psychosis:
    • 84% of studies reported persecutory delusions
    • 69% reported auditory hallucinations
    • 65% reported visual hallucinations
    • 53% reported hostility
    • 36% reported conceptual/cognitive disorganization
  • In most cases, psychotic symptoms associated with methamphetamine are transient, and fade after discontinuation of use
  • Various studies show persistent psychotic symptoms in roughly 25% of methamphetamine users, which remain for a month or more
  • Duration of use and severity of symptoms predicted persistence of symptoms
  • Studies indicate persistence of psychotic symptoms among methamphetamine users were specifically related to family history of psychosis/psychotic disorder

Hallucinogens

  • Prevalence of use: 18.9% (48.3million) of adults 18+ report hallucinogen use during their lifetime
  • Prevalence of psychosis/psychotic symptoms among hallucinogen users:
    • LSD: 20.9%
    • Psilocybin mushrooms: 18.8%
  • A common misunderstanding is that hallucinations are part of the hallucinogenic experience, however, experts indicate these changes in perception – size, shape, color, illusion of movement, synesthesia – are alterations of visual perception, and rarely represent true hallucinations
  • Studies on the long-term use of hallucinogens report no associations between use of psychedelics
  • A study published in 2018 reported that “…no cases of prolonged psychosis or hallucinogen persisting perception disorder have been reported in modern trials with psilocybin…or LSD.”

The research team also examined the impact of MDMA, PCP, and ketamine on psychotic symptoms and substance-induced psychosis. Those results are even more complex than those above, and in some cases, contradictory, and are therefore beyond the scope of this article.

What Does This Research Mean?

In a nutshell, this research tells us that the strongest association between substance-induced psychosis and subsequent conversion to a psychotic disorder appeared among patients with cannabis-induced psychotic events, with research showing people who experience cannabis-induced psychosis subsequently develop schizophrenia at a rate of 41.2%.

In fact, cannabis and cannabinoids are the only classes of drugs for which evidence of conversion to a psychotic disorder exists – to date. Here’s what the research team concluded about the recent increase in use of MDMA and other classic hallucinogens:

“Although the possible association with psychotic symptomatology seems clear, the scientific community is far from being able to provide conclusive evidence on this topic.”

That disclaimer notwithstanding, the data in this new study supports and confirm our previous understanding of the relationship between substance use, substance-induced psychosis, and psychotic disorders.

Psychotic symptoms are more likely related to a primary psychotic disorder among:

  • Younger patients
  • Patients with a family history of mental illness/psychotic illness
  • Patients with high baseline scores of unusual content of thought on the Brief Psychiatric Rating Scale (BPRS)

Psychotic symptoms are more likely attributable to substance-induced psychosis when:

  • Patients have no family history of psychotic disorders
  • Hallucinations are mostly visual
  • Patients have substance use disorder (SUD)
    • Chronic, severe SUD further increases risk
  • Patients report more symptoms of depression /anxiety than psychosis
  • Patients report higher rates of suicidal ideation

This data helps inform our approach to treatment by clarifying what we know and don’t know. We know what increases risk of substance-induced psychosis and conversion of substance-induced psychosis to a psychotic disorder. We know that strongest associations between substance-induced psychosis and conversion to a psychotic disorder appear between cannabis-induced psychosis and schizophrenia. Mental health researchers strongly suspect to identify further conversion trends for substances like MDMA, but as of now, the results are inconclusive.

Treatment for Substance-Induced Psychosis

The first step in helping a person with substance-induced psychosis is the immediate discontinuation of substance use in a medically safe environment. In most cases, resolving substance-induced psychosis requires two things:

  • Abstinence from the substance
  • Time

In other cases, anxiolytics may help ease the transition, and in the case of methamphetamine or amphetamine-induce psychosis, providers may temporarily prescribe an antipsychotic medication to reduce psychotic symptoms.

If we subsequently diagnose a patient with substance use disorder (SUD), we create an integrated, holistic treatment plan that includes therapy, counseling, lifestyle changes, medication (if needed), community support, family support, and adjunct/experiential therapies.

If we diagnose the presence of a psychotic disorder – e.g. schizophrenia – after a period of abstinence from substance use, then we create a treatment plan that best addresses that disorder. In the case of schizophrenia, treatment may include medication, psychiatry, lifestyle changes, and adjunct/experiential therapies.

This topic is front-of-mind for many mental health and SUD treatment providers in 2023. Increases in polysubstance use and co-occurring disorders – as reported in the new National Survey on Drug Use and Health (2022 NSDUH) – combined with the recent trend toward legalization of recreational cannabis nationwide means we may see an increase in substance-induced psychosis and conversion to psychotic disorders in the years ahead.

This information will help us with the most important piece of the puzzle: arriving at an accurate, verifiable diagnosis. Once we separate the substance from the psychosis – or connect the substance to a subsequent psychotic disorder – we can create an appropriate treatment plan that offers our patients the greatest chance of success.