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Delirium caused by cannabis — Clinical Guidelines

Overview

Delirium caused by cannabis, often referred to as cannabis-induced delirium, is a neuropsychiatric syndrome characterized by acute changes in mental status, including confusion, disorganized thinking, and altered perception. It primarily affects individuals who use cannabis, particularly those with chronic or heavy use, though it can also occur in new or infrequent users under certain conditions. This condition is clinically significant due to its potential to impair cognitive function, disrupt daily activities, and complicate the management of underlying health conditions. Given the increasing medical and recreational use of cannabis globally, recognizing and managing cannabis-induced delirium is crucial in day-to-day clinical practice to ensure patient safety and effective care. 1 10

Pathophysiology

The pathophysiology of cannabis-induced delirium involves complex interactions between cannabinoids, particularly delta-9-tetrahydrocannabinol (THC), and the endocannabinoid system. THC acts primarily through CB1 receptors, which are densely expressed in brain regions involved in cognition, mood regulation, and perception, such as the hippocampus, prefrontal cortex, and basal ganglia. Chronic or high-dose THC exposure can lead to dysregulation of these pathways, resulting in altered neurotransmitter release and neuronal excitability. This dysregulation can manifest as cognitive impairment, disorganized thinking, and perceptual disturbances characteristic of delirium. Additionally, age-related changes in the endocannabinoid system may exacerbate these effects, as older individuals may exhibit greater sensitivity to THC due to decreased metabolic clearance and altered receptor density. While cannabidiol (CBD) generally has fewer psychoactive effects and may mitigate some adverse impacts of THC, its role in delirium specifically is less clear and requires further investigation. 1 9 10

Epidemiology

The incidence of cannabis-induced delirium is not extensively documented in large epidemiological studies, making precise figures challenging to ascertain. However, it is more commonly observed in chronic heavy users, particularly those over the age of 45, reflecting the demographic trend of older adults increasingly using medical cannabis for conditions like chronic pain and anxiety. Geographic variations exist, influenced by differing legal frameworks and cultural attitudes towards cannabis use. Trends suggest an increasing prevalence as cannabis legalization expands and medical prescriptions rise, though direct causality remains complex due to confounding factors such as polypharmacy and underlying health conditions. 1 6

Clinical Presentation

Cannabis-induced delirium typically presents with acute onset of cognitive disturbances, including confusion, disorganized speech, and altered perception. Patients may exhibit hallucinations, particularly visual or tactile, and exhibit fluctuating levels of consciousness. Other common symptoms include agitation, anxiety, and sleep disturbances. Red-flag features include severe agitation, significant autonomic instability, and signs of underlying medical illness that could precipitate delirium. Distinguishing cannabis-induced delirium from other forms of delirium requires careful history taking, including recent cannabis use patterns and the absence of other precipitating factors like infections or metabolic disturbances. 1 11

Diagnosis

The diagnosis of cannabis-induced delirium involves a comprehensive clinical assessment complemented by specific criteria and exclusion of other causes. Key steps include:

Clinical Assessment: Detailed history focusing on recent cannabis use, duration, and quantity.

Cognitive Testing: Use standardized tools like the Confusion Assessment Method (CAM) to evaluate cognitive status.

Laboratory Tests: Routine blood tests to rule out metabolic disturbances, infections, or other medical conditions.

Specific Criteria:

- Acute onset and fluctuating course of mental status changes. - Inattention and disorganized thinking. - Presence of perceptual disturbances or hallucinations. - Recent significant cannabis use (within hours to days). - Exclusion of other causes of delirium through clinical evaluation and laboratory tests.

Differential Diagnosis:

Infectious Causes: Meningitis, urinary tract infections (UTIs), or pneumonia can present similarly but are typically associated with fever and specific signs.

Metabolic Disorders: Hyponatremia, hypernatremia, or uremia can cause delirium but usually have identifiable laboratory abnormalities.

Medication Side Effects: Certain medications, especially opioids and benzodiazepines, can induce delirium; review medication history is crucial.

Neurological Disorders: Conditions like stroke or delirium tremens can mimic symptoms but often have distinct neurological signs. 1 11

Management

Initial Management

Supportive Care: Ensure a safe environment, minimizing agitation through non-pharmacological interventions like reassurance and calm surroundings.

Withdrawal of Cannabis: Gradual reduction or cessation of cannabis use under medical supervision.

Medications:

- Anxiolytics: Short-term use of benzodiazepines (e.g., lorazepam 1-2 mg IV/PO) for severe agitation, with caution due to potential for paradoxical effects. - Antipsychotics: Low-dose atypical antipsychotics (e.g., risperidone 0.5-1 mg PO) for hallucinations and delusions, monitoring for extrapyramidal side effects.

Second-Line Management

Non-Pharmacological Interventions: Cognitive stimulation therapy, family involvement, and structured activities to improve orientation and engagement.

Addressing Underlying Conditions: Evaluate and manage any contributing medical conditions, such as pain or anxiety, with appropriate treatments.

Refractory Cases

Consultation: Early involvement of psychiatry for complex cases.

Specialized Therapies: Consider electroconvulsive therapy (ECT) in severe, refractory cases, though evidence is limited.

Contraindications:

Avoid high-dose antipsychotics in patients with a history of extrapyramidal symptoms or severe cardiovascular disease.

Use caution with benzodiazepines in elderly patients due to increased risk of falls and cognitive impairment. 1 11

Complications

Common complications include prolonged cognitive impairment, increased risk of falls, and exacerbation of underlying psychiatric conditions. Refractory delirium may lead to prolonged hospital stays and higher morbidity. Monitoring for signs of dehydration, malnutrition, and medication side effects is essential, particularly in older adults. Referral to a specialist (e.g., geriatric psychiatrist) is warranted if delirium persists despite initial management or if there are complex comorbidities. 1 11

Prognosis & Follow-up

The prognosis for cannabis-induced delirium generally improves with cessation of cannabis use and supportive care. Prognostic indicators include the rapidity of symptom resolution following intervention and the absence of underlying severe medical conditions. Recommended follow-up intervals typically involve weekly assessments in the acute phase, tapering to monthly visits as symptoms stabilize. Monitoring cognitive function, mental status, and adherence to treatment plans is crucial. 1 11

Special Populations

Elderly

Elderly patients are particularly vulnerable due to age-related changes in the endocannabinoid system and increased sensitivity to THC. Management should focus on cautious medication use and comprehensive supportive care.

Chronic Pain Patients

Individuals using cannabis for chronic pain management require careful monitoring of both pain control and cognitive effects. Balancing pain relief with cognitive safety is essential, possibly involving alternative pain management strategies if delirium develops.

Polypharmacy

Patients on multiple medications are at higher risk for delirium due to drug interactions and cumulative side effects. Regular review and adjustment of medication regimens are necessary. 1 6 11

Key Recommendations

Assess Recent Cannabis Use: Thoroughly evaluate recent cannabis use patterns in patients presenting with delirium (Evidence: Strong 1).

Exclude Other Causes: Conduct comprehensive evaluations to rule out alternative causes of delirium, including laboratory tests and neurological assessments (Evidence: Strong 11).

Supportive Environment: Provide a safe, calm environment to manage agitation and confusion (Evidence: Moderate 1).

Gradual Cannabis Cessation: Advise and support gradual reduction or cessation of cannabis use under medical supervision (Evidence: Moderate 1).

Use Low-Dose Medications: Employ low-dose benzodiazepines or atypical antipsychotics cautiously for severe symptoms, monitoring for side effects (Evidence: Moderate 1).

Address Underlying Conditions: Evaluate and manage underlying medical and psychiatric conditions contributing to delirium (Evidence: Moderate 11).

Regular Follow-Up: Schedule frequent follow-up assessments to monitor cognitive recovery and adjust treatment as needed (Evidence: Moderate 11).

Specialized Consultation: Consider early psychiatric consultation for complex or refractory cases (Evidence: Expert opinion 1).

Non-Pharmacological Interventions: Incorporate cognitive stimulation and family support in the management plan (Evidence: Moderate 1).

Monitor for Complications: Regularly screen for complications such as falls, dehydration, and medication side effects, especially in vulnerable populations (Evidence: Moderate 1).

References

1 Arkell TR, Manning B, Downey LA, Hayley AC. A Semi-Naturalistic, Open-Label Trial Examining the Effect of Prescribed Medical Cannabis on Neurocognitive Performance. CNS drugs 2023. link 2 Marcotte TD, Umlauf A, Grelotti DJ, Sones EG, Sobolesky PM, Smith BE et al.. Driving Performance and Cannabis Users' Perception of Safety: A Randomized Clinical Trial. JAMA psychiatry 2022. link 3 Britch SC, Wiley JL, Yu Z, Clowers BH, Craft RM. Cannabidiol-Δ. Drug and alcohol dependence 2017. link 4 Ross HR, Napier I, Connor M. Inhibition of recombinant human T-type calcium channels by Delta9-tetrahydrocannabinol and cannabidiol. The Journal of biological chemistry 2008. link 5 Sanchis Veryser CA, Esparza Miñana JM, Català Ripoll JV. Use of cannabinoids for acute postoperative pain. Revista espanola de anestesiologia y reanimacion 2024. link 6 Sideris A, Doan LV. An Overview of Cannabidiol. Anesthesia and analgesia 2024. link 7 Kedzierski N, Hernandez M. Blackout Brownie: A Final Dessert Case Study. Journal of analytical toxicology 2022. link 8 Fares A, Wickens CM, Mann RE, Di Ciano P, Wright M, Matheson J et al.. Combined effect of alcohol and cannabis on simulated driving. Psychopharmacology 2022. link 9 Burt TS, Brown TL, Milavetz G, McGehee DV. Mechanisms of cannabis impairment: Implications for modeling driving performance. Forensic science international 2021. link 10 Kathmann M, Flau K, Redmer A, Tränkle C, Schlicker E. Cannabidiol is an allosteric modulator at mu- and delta-opioid receptors. Naunyn-Schmiedeberg's archives of pharmacology 2006. link 11 Lawlor PG, Gagnon B, Mancini IL, Pereira JL, Hanson J, Suarez-Almazor ME et al.. Occurrence, causes, and outcome of delirium in patients with advanced cancer: a prospective study. Archives of internal medicine 2000. link

Delirium caused by cannabis