Schizophrenia

Schizophrenia is a mental illness that severely impairs social and mental functioning.

Epidemiology

• Incidence – 2-4/1000
  • Lifetime prevalence of 1%
• Age –  onset in 20’s; younger age for men
• Sex – equal distribution

Risk Factors

• Family history is strongly correlated
• Other, less-correlated, factors
  • Cannabis use
  • CNS infection in childhood
  • Maternal obstetrical complications

Pathophysiology

• Neurotransmitter is likely involved in dopamine transmission
  • Drugs that induce states similar to schizophrenia increase dopaminergic transmission
  • Drugs that treat schizophrenia decrease dopaminergic transmission

Clinical Presentation

• Hallucinations, delusions
• Disorganized speech
• Disorganized behavior
• Signs and symptoms must be present >30 days in the absence of treatment

Diagnosis

• Based on clinical presentation

Differential Diagnosis

• Brief psychotic episode
• Delirium
• Acute or chronic medical illness
• Substance abuse
• Schizophreniform disorders
• Medication-induced disorder
• Pervasive developmental disorder

Therapeutic Drug Management

• Pharmacogenetic testing may guide drug and dose selection
• Periodic drug monitoring is useful to assure compliance, identify drug-drug interactions or other reasons to adjust dosing, and may establish optimal therapeutic ranges for an individual patient.  Suggested therapeutic ranges and toxic thresholds are available for some but not all commonly used antipsychotic drugs
• Additional clinical testing (such as WBC) is required for some drugs to detect toxicity

Treatment

• Antipsychotic drugs are the mainstay of therapy
  • Some require monitoring for correct dosing
• Dopamine D2 antagonists – chlorpromazine, clozapine, fluphenazine, fluphenazine decanoate, haloperidol, haloperidol decanoate, loxapine, molindone, perphenazine, thioridazine, thiothixene, trifluoperazine
• Atypical mixed neuroreceptor antagonists (low affinity D2 antagonists, high-affinity 5-HT2A antagonists) – aripiprazole, chlorpromazine, clozapine, olanzapine, quetiapine, risperidone, thioridazine, ziprasidone
• Hepatic phase 1 oxidation is catalyzed by cytochrome P450 (CYP)
  • Inheritance of clinically significant CYP2D6 variants alter drug metabolism

Indications for Ordering

• Tests generally appear in the order most useful for common clinical situations
• Click on number for test-specific information in the ARUP Laboratory Test Directory