Management of psychosis in the context of cannabis use: Beyond the chicken or the egg question

CASE PRESENTATION

A 17-year-old male is brought to the emergency room by a friend who finds him strange lately. The patient is very anxious and seems to be scared. He reports having recently discovered that government was spying on him, using a complex network of cameras and satellites. He has unplugged all of his house hold electronic devices and refuses to talk to his friend on the phone. During the interview, the patient is not sure if he can trust you. He explains suffering from insomnia because he is afraid of being kidnapped while sleeping. His friend reports that he was doing well until this week. He has never seen his friend like this before.

The patient has been smoking cannabis for the past year. He first started smoking once or twice a week, then gradually increased his use because he thinks that it helps him to relax and sleep. He has been feeling very stressed and restless for the past few weeks, and has increased his cannabis use to 2 g per day. He rarely drinks alcohol and does not use any other substances. The patient does not make any links between his substance use and his current state.

DISCUSSION

In the acute phase, substance-induced psychosis and primary psychotic disorder can share clinical manifestations. It can be challenging to differentiate between the two conditions. However, a careful evaluation can provide critical information for guiding the diagnostic process.

Acute cannabis intoxication can induce altered cognitions and perceptions such as delusions of persecution and hallucinations, respectively, which last for a few hours following use and fade after. If cannabis is smoked, symptoms peak after 15 to 30 minutes and typically last for 2 to 3 hours. When consumed orally, there is a delay of a couple of hours before the symptoms appear, lasting up to 12 hours. This duration can vary depending on metabolism, frequency, quantity, potency, type/strain used, etc. During an intoxication with altered perception, individuals are often at least partially aware that symptoms are not real but sometimes disorganization can be so striking that they lack insight for a short period of time. Regardless of etiology, conviction of delusions and ‘loss of contact with reality’ are inherent to a psychotic episode diagnosis; duration of episode and waxing and waning of symptoms in relation to cannabis use, may be better indicators of whether cannabis is the underlying cause. It should be carefully evaluated to differentiate cannabis-induced from an underlying primary psychotic disorder such as schizophrenia or bipolar disorder. Even with a good evaluation, it is not always possible to make the distinction during acute psychosis.

To increase the likelihood of an accurate diagnosis, collateral information is helpful (e.g., noticeable changes in behaviour or speech, timeline of symptoms, duration, etc.). No single sign or symptom can confirm the diagnosis, however, a constellation of signs or symptoms are good clinical indicators. Assessing the temporal correlation of symptom onset and intensity with use pattern can be helpful; for example, if mild symptoms appear quickly in the context of intensive cannabis use and resolve rapidly over a few days, and the functioning before and after this episode is good, it is more likely induced. The cut-off of 1 month for symptoms to resolve is generally used although induced psychosis frequently lasts for a few days. The longer the symptoms last, the more prudent one should be before excluding a diagnosis of primary psychotic disorder. Signs indicating an increased risk of a primary psychotic disorder include (i) soft psychotic symptoms (e.g., suspiciousness, brief hallucination), (ii) altered functioning (e.g., social isolation, lower grades at school) before the episode (taking into consideration, however, that cannabis use disorder can alter functioning as well), (iii) symptoms that look out of proportion with the amount and duration of cannabis use (e.g., bizarre or complex delusions after using cannabis once a week for few weeks), (iv) psychotic symptoms unrelated to cannabis use, or present in sustained periods of abstinence, (v) repetitive episodes, and (vi) family history of psychotic disorder.

Cannabis use is not the only factor that increases the risk of psychosis. Most heavy cannabis users will never develop the disorder, which stems from multiple factors such as genetic, trauma, immigration, birth complications, and others. That being said, multiple studies have associated cannabis use with a greater risk of developing a psychotic disorder like schizophrenia, more so when use is frequent and if products used contain high THC levels.

Although the aforementioned information may help to specify the diagnosis, one must remember that such an endeavour is often challenging and that the initial clinical impression may need to be reconsidered in the long run. Studies showed that almost 50% of patients initially diagnosed with cannabis-induced psychosis will be later on diagnosed with a primary psychotic disorder (schizophrenia spectrum, bipolar disorder) (1). Therefore, guidelines suggest that induced or not, emerging psychosis in the context of cannabis use lasting more than a few days should be managed following the first episode of psychosis (2). Systematic follow-up should be offered to provide evidence-based interventions for both mental health and substance use, and ultimately, to attempt to reduce the risk of chronic psychosis.

CLINICAL PEARLS

• 1.

  Cannabis intoxication, cannabis-induced psychosis and concurrent psychotic disorder with cannabis use can present with similar clinical features; collateral information, past history, and thorough evaluation may help to guide the diagnosis process.

• 2.

  Almost 50% of cannabis-induced psychosis may evolve into a diagnosis of primary psychotic disorder.

• 3.

  Whether cannabis-induced or primary, offering systematic follow-up, and management of psychosis in the context of cannabis use is important, as well as addressing substance use/misuse as indicated.

Informed consent: Informed consent was not required because the case represented here is fictional.

Funding: There are no funders to report for this submission.

Potential Conflicts of Interest: DJ-A reports nonfinancial support from Insys Therapeutics outside the submitted work. There are no other disclosures. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

References