What is the treatment for an 18-year-old patient with drug-induced psychosis?

Treatment for Drug-Induced Psychosis in an 18-Year-Old

For an 18-year-old with drug-induced psychosis, initiate treatment with an atypical antipsychotic (risperidone 2 mg/day or olanzapine 7.5-10 mg/day) combined with benzodiazepines for acute stabilization, while ensuring the patient achieves abstinence from the causative substance. 1, 2

Initial Assessment and Stabilization

Before initiating antipsychotic treatment, you must rule out medical emergencies that can mimic or complicate drug-induced psychosis:

• Evaluate level of consciousness and orientation - altered consciousness suggests delirium or medical emergency requiring different management rather than pure psychosis 1
• Assess for CNS infections, traumatic brain injury, and other intracranial processes that may require urgent intervention 1
• Test for asterixis and myoclonus which indicate metabolic encephalopathy rather than substance-induced psychosis 1
• Screen for alcohol or benzodiazepine withdrawal - these can cause both psychosis and life-threatening seizures requiring immediate benzodiazepine treatment 1
• Consider neuroimaging in new-onset psychosis to exclude structural lesions, particularly if focal neurological signs, head trauma history, or atypical features are present 1

Acute Pharmacological Management

Start with atypical antipsychotics as first-line treatment:

• Risperidone 2 mg/day OR olanzapine 7.5-10 mg/day are the recommended initial target doses 2
• Add short-term benzodiazepines as adjuncts to help stabilize the acute clinical situation 2
• Avoid large initial doses - they increase side effects without hastening recovery 1, 2
• Expect antipsychotic effects after 1-2 weeks, though any immediate effects are likely due to sedation 1, 2

The atypical antipsychotics are preferred over traditional neuroleptics because they have better tolerability profiles and are at least as effective for positive symptoms 3, 2. This is particularly important in an 18-year-old where medication adherence will be crucial for long-term outcomes.

Treatment Duration and Monitoring

Implement a 4-6 week trial before determining efficacy:

• Continue adequate dosages for the full 4-6 weeks before concluding treatment failure 1, 2
• Monitor closely for extrapyramidal side effects - avoiding these is critical to encourage future medication adherence 2
• Document target symptoms, treatment response, and any side effects including weight gain and metabolic changes 3

Drug-induced psychosis is expected to resolve after a 30-day period of sobriety, so antipsychotics may be used short-term with gradual discontinuation when the patient is stable 4, 5. However, maintain vigilance as conversion rates to schizophrenia or bipolar disorder can be as high as one in three individuals, particularly in cannabis users and those with early-onset substance abuse 4.

If First Treatment Fails

If symptoms persist after 4-6 weeks or side effects are unmanageable:

• Switch to a different antipsychotic with a different pharmacodynamic profile 1, 2
• Consider amisulpride, paliperidone, or an alternative atypical agent if the first-line treatment was ineffective 2
• Reassess the diagnosis and contributing factors after two adequate treatment trials (at least 4 weeks each) 2

Treatment-Resistant Cases

For treatment-resistant psychosis after failure of two adequate trials:

• Consider clozapine - it is the only antipsychotic with documented superiority for treatment-refractory cases 2, 5
• Use clozapine only after failure of at least two other antipsychotic agents (at least one being atypical) 3, 2
• Implement required monitoring protocols for agranulocytosis and seizures with clozapine 3

Psychosocial Interventions

Combine pharmacological treatment with comprehensive psychosocial support:

• Include the family in assessment and treatment planning - provide them with emotional support and practical advice 1, 2
• Provide psychoeducation to the patient about the illness, treatment options, relapse prevention, and the risks of continued substance use 3
• Ensure continuity of care with the same treating clinicians for at least 18 months 1, 2
• Implement relapse prevention strategies focusing on sustained abstinence from the causative substance 4

Long-Term Management Considerations

After acute symptom resolution:

• Maintain antipsychotic medication for 1-2 years after the initial episode given the risk for relapse and potential conversion to primary psychotic disorder 3
• Consider gradual dose reduction to decrease side effects once the patient is stable, but balance this against relapse risk 3, 2
• Monitor for conversion to schizophrenia or bipolar disorder - episodes of self-harm after substance-induced psychosis are strongly linked to elevated likelihood of developing these conditions 4

Critical Pitfalls to Avoid

• Don't miss delirium - fluctuating consciousness, disorientation, and inattention distinguish delirium from psychosis and require different urgent evaluation 1
• Don't switch medications too early (before 4-6 weeks) or continue ineffective treatment too long 2
• Don't abruptly discontinue antipsychotics after acute symptom resolution - maintenance therapy prevents relapse 2
• Don't neglect side effect monitoring - this is a common reason for medication non-compliance, particularly in young adults 2
• Don't overlook the need for substance abuse treatment - continued substance use will undermine psychiatric treatment and increase risk of severe addiction 4