What intake questions should I ask a patient with cannabis-induced psychosis as a Psychiatric Mental Health Nurse Practitioner (PMHNP)?

Intake Assessment for Cannabis-Induced Psychosis

Cannabis Use History

Your intake must establish detailed cannabis consumption patterns to differentiate cannabis-induced psychosis from primary psychotic disorders and assess withdrawal risk. 1, 2

Quantity and Frequency Assessment

• Daily cannabis consumption amount (specifically >1.5g/day of smoked cannabis or >20mg/day THC oil increases risk for cannabis withdrawal syndrome and persistent psychosis) 1
• Frequency of use (daily or weekly use, particularly if initiated before age 18, strongly predicts worse outcomes and progression to independent psychiatric disorders) 3, 2
• Duration of regular use (>1 year of use before symptom onset is a diagnostic criterion for cannabinoid hyperemesis syndrome) 1
• THC potency and product type (concentrates with up to 70% THC versus traditional cannabis with 9-17% THC significantly alter risk profiles) 3
• Route of administration (smoked, vaped, edibles, oils—each has different onset times and bioavailability affecting symptom presentation) 1

Temporal Relationship to Psychosis

• Age at first cannabis use (use ≤18 years is associated with poor prognosis and increased risk of developing independent schizophrenia-spectrum disorders) 2, 4
• Time between last use and psychotic symptom onset (symptoms occurring during acute intoxication versus persisting beyond 24-72 hours distinguish acute from persistent psychosis) 1, 5
• Pattern of symptom emergence (acute onset during/after use versus gradual development suggests different diagnostic trajectories) 6, 5

Psychotic Symptom Characterization

Symptom Profile Assessment

• Predominant symptom type (affective versus non-affective psychosis—patients with predominantly non-affective symptoms have 50% risk of progressing to independent psychiatric disorder versus only 7.7% with affective symptoms) 2
• Specific psychotic symptoms present: auditory hallucinations (less common in cannabis-induced psychosis at 60.3% versus schizophrenia), visual hallucinations, paranoia, delusions 6
• Negative symptoms (lower negative symptom scores on PANSS suggest cannabis-induced psychosis rather than schizophrenia) 6
• Presence of manic symptoms (26.1% of cannabis-induced psychosis patients present with mania versus 12.3% in schizophrenia with cannabis use) 6
• Cognitive symptoms (attention deficits, executive function impairment, memory problems—particularly severe when use began in adolescence) 3

Symptom Severity and Duration

• Current symptom intensity (high-dose THC is associated with more severe acute psychotic symptoms) 3
• Duration of current episode (symptoms persisting >1 month beyond cessation suggest transition to independent disorder) 5
• Number and timing of previous psychotic episodes (all patients who relapsed to cannabis use had recurrence of illness) 2

Risk Factors for Persistent Psychotic Disorder

Genetic and Family History

• Family history of psychotic disorders (positive family history predicts poor prognosis and progression to independent disorder) 2
• Family history of mood disorders, particularly bipolar disorder (cannabis exacerbates manic and psychotic symptoms in bipolar patients) 7
• Family history of substance use disorders 2

Developmental and Social Factors

• Age at first psychotic episode (younger age at onset associated with poor prognosis) 2, 4
• Marital status (being unmarried associated with poor prognosis) 2
• Socioeconomic status (lower status associated with poor prognosis) 2
• History of childhood trauma or abuse (increases risk of persistent psychosis with cannabis exposure) 5
• Current social and occupational functioning (marked impairment suggests more severe disorder) 2

Cannabis Withdrawal Syndrome Screening

Cannabis withdrawal symptoms occur 24-72 hours after cessation, peak in the first week, and last 1-2 weeks, potentially contributing to postoperative or acute care morbidity. 1

DSM-5 Withdrawal Criteria Assessment

• Irritability or anger 1, 3
• Anxiety symptoms 1, 3
• Sleep disturbances or insomnia 1, 3
• Decreased appetite or weight changes 1, 3
• Restlessness or psychomotor agitation 1
• Depressed mood 1
• Physical symptoms: abdominal pain, tremors, sweating, fever, chills, headache 1, 3

Cannabinoid Hyperemesis Syndrome Assessment

• Cyclic vomiting pattern (stereotypical episodic vomiting occurring ≥3 times annually) 1
• Compulsive hot water bathing behavior (prolonged hot baths or showers that relieve symptoms, reported in 71% of cases) 1
• Abdominal pain pattern 1
• Nausea severity and timing 1

Substance Use Comorbidity

• Concurrent tobacco use (combined use causes greater increases in heart rate and vasoconstriction than either alone) 3
• Alcohol use patterns 5
• Other illicit substance use (particularly stimulants or hallucinogens that may confound presentation) 8
• Prescription medication use (particularly opioids, which may reduce cannabis withdrawal symptoms) 1

Medical Comorbidities and Complications

Cardiovascular Assessment

• History of arrhythmias (cannabis use associated with adverse cardiovascular events including arrhythmias) 3
• History of myocardial infarction or ischemia (particularly relevant in older adults where acute cannabis toxicity can precipitate MI) 3
• Orthostatic hypotension symptoms 1, 3
• Tachycardia or palpitations 3

Respiratory Assessment

• Chronic cough or bronchitis symptoms (cannabis smoking associated with chronic bronchitis and COPD) 3
• History of vaping-related lung injury (2019 outbreak associated with THC concentrate and vitamin E acetate) 3

Neurological Assessment

• Cognitive deficits: executive function, verbal learning and memory, attention, processing speed (particularly severe with adolescent-onset use) 3
• History of seizures or epilepsy 1
• History of stroke or TIA (cannabis use associated with increased stroke risk) 3, 7

Psychiatric Comorbidity Screening

• Pre-existing psychiatric diagnoses (depression, anxiety, bipolar disorder—cannabis may exacerbate all of these) 3
• History of suicidal ideation or attempts (early cannabis use associated with increased suicidal ideation) 3
• Symptoms of cannabis use disorder (approximately 10% of chronic users develop clinically significant impairment or distress) 3, 7
• Previous psychiatric hospitalizations (timing relative to cannabis use) 4

Functional Impact Assessment

• Changes in social functioning (patients who abstained showed marked improvement in socio-occupational functioning) 2
• Occupational or academic performance decline 2
• Relationship difficulties 2
• Legal problems related to cannabis use 3
• Motor vehicle accidents or near-misses (cannabis users have more than double the risk of motor vehicle accidents) 7

Treatment History and Response

• Previous abstinence attempts and duration (complete abstinence after first episode prevents relapse; abstinence later in course does not improve outcome significantly) 2
• Previous psychiatric treatments and response 2
• Previous emergency department visits for cannabis-related issues (particularly relevant in older adults) 3
• Current medications (particularly antipsychotics, which may interact with cannabis) 1

Critical Prognostic Indicators

Patients who completely abstain from cannabis after the first episode have no relapse of psychiatric illness, while all those who relapse to cannabis use have recurrence. 2 This makes abstinence assessment and planning the single most important prognostic factor to establish during intake.

High-Risk Features for Progression to Schizophrenia-Spectrum Disorder

• Predominantly non-affective psychotic symptoms (50% progression rate versus 7.7% for affective symptoms) 2
• Cannabis use onset ≤18 years 2, 4
• Positive family history of psychosis 2
• Male gender and young age (associated with increased risk of developing schizophrenia-spectrum disorders) 4
• Continued cannabis use after initial episode 2

Objective Measures Consideration

Self-report accuracy may be impaired by psychotic symptoms, cognitive deficits, and desire to conceal use when clinicians have advised against it. 8 Consider:

• Urinary THC screening (though rarely used routinely, provides objective confirmation) 8
• Quantitative cannabinoid measurement in urine or blood (more accurate than self-report but rarely done clinically) 8

Common Pitfalls to Avoid

• Do not assume cannabis-induced psychosis is benign: 44.5% develop schizophrenia-spectrum disorders and 77.2% have new psychotic episodes of any type during follow-up 4
• Do not miss the delayed onset pattern: 47.1% of patients receive schizophrenia diagnosis more than one year after initial cannabis-induced psychosis treatment 4
• Do not overlook withdrawal risk: patients consuming >1.5g/day smoked cannabis or >20mg/day THC oil require withdrawal monitoring 1
• Do not fail to assess for cannabinoid hyperemesis syndrome: this requires cannabis cessation as primary treatment 1
• Do not ignore cardiovascular risk: particularly in older adults where acute toxicity can precipitate myocardial ischemia 3