What is drug-induced psychosis and how is it treated?

Drug-Induced Psychosis: Diagnosis, Treatment, and Prognosis

Drug-induced psychosis is a secondary psychotic disorder resulting from substance use that requires prompt identification of the causative substance, discontinuation of the offending agent, and treatment with supportive care and short-term antipsychotics, with most cases resolving within 30 days of sobriety but carrying a significant risk (up to one in three) of conversion to schizophrenia or bipolar disorder. 1

Definition and Clinical Presentation

• Drug-induced psychosis (also called substance-induced psychosis) is characterized by psychotic symptoms directly related to substance use, including hallucinations and delusions 2
• Unlike other forms of altered mental status, patients with psychosis typically maintain intact awareness and level of consciousness 3
• Cardinal features include delusions, hallucinations, disorganized speech/thought, abnormal motor behavior, and negative symptoms (diminished emotional expression) 3
• Psychotic symptoms may be preceded by mood changes and anxiety, particularly with certain medications like steroids and antimalarials 2

Common Causative Substances

• Major causes include recreational drugs: cocaine, amphetamines, phencyclidine, cannabinoids, LSD, mescaline, designer drugs 4
• Medication-induced psychosis can occur with: steroids, antiepileptic drugs, antimalarial drugs, antiretroviral drugs 2
• Other causes include anticholinergic compounds and drug withdrawal states 4
• Risk factors include female sex and pre-existing psychiatric history for most medication-induced psychotic disorders 2

Diagnostic Approach

• Differentiate between primary psychosis (schizophrenia, bipolar disorder) and secondary drug-induced psychosis by establishing the temporal relationship between substance use and symptom onset 5
• Rule out medical emergencies and investigate underlying causes, including central nervous system infections and traumatic brain injury 6
• Consider neuroimaging in patients with new-onset psychosis to exclude intracranial processes requiring intervention 6, 3
• Assess for risk of self-harm or aggression to determine appropriate treatment setting 6

Treatment Algorithm

Acute Management

1. Discontinue the offending substance - First and most critical step in management 2
2. Provide supportive care - General supportive measures, reassurance, and minimizing patient stimulation 4
3. Consider benzodiazepines - For short-term management of agitation and anxiety 6, 4
4. Short-term antipsychotics - When necessary for symptom control 1
   • Atypical antipsychotics are preferred due to better tolerability and fewer extrapyramidal side effects 7
   • Start with low doses: risperidone 2 mg/day or olanzapine 7.5-10.0 mg/day 7
   • Avoid large initial doses as they increase side effects without hastening recovery 6
5. Specific interventions when indicated:
   • Physostigmine for anticholinergic poisoning 4
   • Urinary acidification to enhance excretion of amphetamines or phencyclidine 4

Ongoing Management

• Implement antipsychotic treatment for 4-6 weeks before determining efficacy 6
• Antipsychotic effects typically become apparent after 1-2 weeks (immediate effects are likely due to sedation) 6
• If symptoms persist after an adequate trial (4-6 weeks), consider switching to another antipsychotic with a different pharmacodynamic profile 6, 7
• Gradually taper antipsychotics when the patient is stable, as most cases should resolve after 30 days of sobriety 1

Prognosis and Long-term Considerations

• Drug-induced psychosis is expected to resolve after a 30-day period of sobriety 1
• However, individuals with substance-induced psychosis are at high risk for:
  • Developing severe drug addiction 1
  • Conversion to schizophrenia or bipolar disorder (rates as high as one in three) 1, 8
  • Earlier onset of schizophrenia 1
• Risk factors for conversion to primary psychotic disorders include:
  • Cannabis use 1
  • Early-onset substance abuse 1
  • Episodes of self-harm following substance-induced psychosis 1
• Approximately 25% of those initially diagnosed with substance-induced psychosis will later be diagnosed with a schizophrenia spectrum disorder 8

Important Considerations and Pitfalls

• Carefully evaluate for other toxic effects of the causative drug beyond psychotic symptoms 4
• Avoid excessive initial dosing of antipsychotics, which leads to unnecessary side effects 6, 7
• Don't switch medications too early (before 4-6 weeks) or continue ineffective treatment too long 6
• Include families in the treatment plan and provide them with emotional support and practical advice 6, 7
• Maintain continuity of care with the same treating clinicians for at least the first 18 months of treatment 6, 7
• Consider that substance-induced psychosis shares many features with schizophrenia spectrum disorders and may represent first-episode psychosis in patients with substance use 8