Substance-induced psychotic disorder

It is often extremely difficult to distinguish substance-induced psychosis from other psychotic disorders. With substance-induced psychosis, symptoms (usually delusions and/or hallucinations) tend to appear quickly and last a relatively short time, from hours to days, until the effects of the drug wear off. For some, however, psychosis can persist for days, weeks, months, or longer [170, 171]. It is possible that these people were already at risk for developing a psychotic disorder which has been triggered by substance use [172].

Visual hallucinations are generally more common in substance withdrawal and intoxication than in primary psychotic disorders [173]. Stimulant intoxication, in particular, is more commonly associated with tactile hallucinations, where the patient experiences a physical sensation that they interpret as having bugs under the skin [174, 175]. These are often referred to as ‘ice bugs’ or ‘cocaine bugs’. Visual, tactile and auditory hallucinations may also be present during alcohol withdrawal [176].

People with stimulant psychosis may appear more agitated, hostile, energetic and physically strong, more challenging to contain in a safe environment, and more difficult to calm with sedating or psychiatric medication, than people with psychosis not related to the use of stimulants [177, 178]. Other features that differentiate substance-induced psychosis from schizophrenia include higher likelihood of polysubstance dependence, a forensic history, ASPD, trauma history, parental substance misuse, lower likelihood of family history of psychosis; and a lack of negative and cognitive symptoms with a return to normal inter-episode functioning during periods of abstinence [177]. A case study example of how a person experiencing co-occurring substance-induced psychosis may present is illustrated in Box 10.

It is important to differentiate between symptoms of psychosis and delirium. Delirium presents as a disturbance of consciousness and cognition that represents a significant change from the person’s previous level of functioning. The person has a reduced awareness of their surroundings, their attention wanders, questions often have to be repeated, they have difficulty concentrating, and it may be difficult to engage them in conversation. Changes in cognition may include short-term memory impairment, disorientation (regarding time or place), and language disturbance (e.g., difficulty finding words, naming objects, writing). Perceptual disturbances (e.g., hallucinations) may also occur. Delirium develops over a short period of time (usually hours to days) and tends to fluctuate during the course of the day. For example, a person may be coherent and co-operative in the morning but in the afternoon may be disruptive and wanting to go home to a partner who died years ago. The identification of substance-induced delirium is particularly important for clients undergoing alcohol withdrawal as delirium may progress to delirium tremens, a serious complication that may result in death [176].

Box 10: Case study J: What does substance-induced psychosis look like? Michael’s story

Case study J: Michael’s story

Michael, an 18-year-old who identified as male, was brought to emergency by the police. Michael started screaming at his parents one evening and threatened them with a knife. His parents called 000, and police took Michael to the nearest hospital emergency for an evaluation. Prior to this, Michael’s parents had noticed that he was uncharacteristically irritable and paranoid, spending long periods of time alone in his bedroom. He did not appear to be sleeping well and was observed to be mumbling to himself. For the past month, he had not gone to any of his university classes.

When he arrived at emergency, Michael was extremely agitated and attempted to strike the nurses and security team. He was given intramuscular lorazepam and haloperidol, but following their administration, tried to flee the hospital because he said the staff were trying to kill him. He appeared to be responding to internal stimuli and would not cooperate with anyone who attempted to conduct a psychiatric evaluation. His parents told hospital staff that he had been diagnosed with ADHD about four weeks earlier and had been prescribed lisdexamfetamine by his treating psychiatrist.

Two weeks later, his psychiatrist had increased his lisdexamfetamine, which Michael took in the morning, and also prescribed dexamphetamine for Michael to take every afternoon to help improve his concentration and ability to study. After having a short sleep, Michael appeared calmer and said that he had some exams coming up which he was very worried about, and had taken double doses of his dexamphetamine tablets over the past three days because he didn’t want to sleep, and needed the additional time to prepare for his exams.

Prior to his ADHD diagnosis, Michael had no psychiatric or AOD use history. His urine toxicology was positive only for amphetamines. Michael had no history of any medical condition, no history of seizures or head trauma. There was no family history of any psychiatric disorders. Michael’s stimulant medications were discontinued when he was admitted to emergency, and he was treated with risperidone. Michael also started psychotherapy. After five days, Michael was no longer experiencing any hallucinations or delusions, and he was released from hospital with a follow-up appointment to see his psychiatrist.

Key Points

Symptoms of psychosis emerged within hours of Michael’s increased ADHD medication. Following withdrawal from his medication, the psychotic symptoms dissipated within a few days, and Michael regained insight into the situation.
This pattern of symptoms corresponds with DSM-5-TR substance-induced psychotic disorder, which requires delusions or hallucinations that develop during or soon after medication intoxication or withdrawal. The fact that Michael’s symptoms resolved within several days further supports a medication-induced psychotic disorder – this would not be the case for an independent psychotic disorder.

Adapted from Henning, Kurtom, and Espiridion [179].