Background
Psychosis at music festivals (MFs) differs from the emergency department as the pretest probability of substance induced psychosis vs organic psychosis increases. The MF environment in general may exacerbate both forms of psychosis due to factors such as noise and overstimulation, dehydration, and lack of sleep. Differentiating between these two can be challenging. Several clues which can help delineate the etiology: previous history of psychosis, substance use history, presenting symptoms, speed of onset, and (most importantly) a resolution of symptoms with metabolism of substances (ie time). In general, visual hallucinations common in substance induced psychosis but uncommon in organic psychosis. First episode psychosis at MFs is usually due to LSD.

History

• Previous psychiatric history/psychotic episodes 

• Presenting complaint / thought disorder

• Hallucinations (usually visual, auditory)

• Delusions or Paranoia 

• Tangential or disorganized speech

• Substance use history 

• Type, amount, timing 

• History of trauma/head injury 

• Headache, fevers 

• PMHx and home medications

Physical Exam

• ABCs 

• Signs of head trauma 

• Neurologic exam 

• Pupils, LOC, focal deficits

• Toxidrome findings 

• Pupils 

• Agitation, psychomotor activity

• Diaphoresis 

• Vitals

• Mental status exam

• Thought process and content

Investigations

• Glucose (low)

• Electrolytes – Sodium (low) or Calcium (high)

• Tox screen unlikely to be helpful

Differential Diagnosis

• Drug induced psychosis 

• Mental health disorder (e.g. bipolar disorder, schizophrenia, psychosis NOS, personality disorder) 

• Head injury

• Encephalopathy 

• Seizures/post-ictal state

Management
Initial management of both substance-induced and organic psychosis is the same.Non- pharmacologic management includes trying to settle the patient and de-escalate if they are agitated. Antipsychotics are the mainstay of treatment; use PO medications if a patient is cooperative. Options are summarized in Table 1. Benzodiazepines alone are often insufficient. Extrapyramidal side effects of antipsychotics can be mitigated by co-administration of benztropine. At MFs most patients presenting with first time psychosis can be treated then monitored while they metabolize the causative substance. From experience, oral antipsychotics may need supervision and assistance (observe closely, chase with copious water), or may tie up valuable resources to convince paranoid, intoxicated patients to take an untrusted medication. Recall that ketamine is contraindicated for organic psychosis. Overall, at MFs most cases are substance induced, resolve with time and do not require or benefit from transport to hospital.

Table 2. Comparison of Organic vs Drug-Induced Psychosis