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Difficulty: MediumSchizophrenia and Psychotic Disorders

A 22-year-old university student is evaluated in the psychiatry clinic accompanied by his mother. For the past 9 months, he has become increasingly isolated, claims that his professors are inserting thoughts into his mind, and frequently talks to unseen individuals in his room. His academic performance has significantly declined, leading to academic probation. The mother notes that 4 months ago, he experienced a 3-week period during which he felt profoundly sad, slept up to 16 hours a day, had markedly low energy, experienced poor appetite with a 5-pound weight loss, and expressed excessive guilt over failing his classes. This depressive period resolved spontaneously, and his mood has been completely stable since. However, his bizarre beliefs and auditory hallucinations have continued unchanged without interruption for the entire 9 months. He does not use any illicit substances, and his medical history is unremarkable. Which of the following is the most likely diagnosis?

  1. SchizophreniaAnswer
  2. B
    Schizoaffective disorder
  3. C
    Schizophreniform disorder
  4. D
    Major depressive disorder with psychotic features
  5. E
    Brief psychotic disorder

Answer

Schizophrenia
Schizophrenia is the correct diagnosis because the patient exhibits criterion A symptoms (delusions, hallucinations) causing functional impairment (academic decline) for a continuous duration greater than 6 months. While a 3-week major depressive episode did occur during the illness course, DSM-5 criteria specify that if mood episodes occur, they must be present for a minority of the total duration of the active and residual phases to diagnose schizophrenia. In this case, 3 weeks is a clear minority of the 9-month overall illness, ruling out schizoaffective disorder.

Step-by-Step Solution

1
Identify the primary psychotic symptoms and establish their total duration.
The patient exhibits continuous delusions (thought insertion) and auditory hallucinations that have been present for exactly 9 months.
Establishing the total duration of continuous psychotic symptoms is the first step in differentiating between brief psychotic disorder (<1 month), schizophreniform disorder (1-6 months), and schizophrenia (>6 months).
2
Evaluate the presence, duration, and timing of any mood episodes.
The patient experienced a single 3-week major depressive episode that occurred concurrently with his ongoing psychotic symptoms. For the remaining 8+ months, his mood was euthymic while psychosis persisted.
Analyzing the relationship between mood and psychotic symptoms differentiates primary psychotic disorders from mood disorders with psychotic features and schizoaffective disorder.
3
Apply DSM-5 diagnostic criteria to synthesize the relationship between the mood and psychotic symptoms.
Because psychotic symptoms are present outside of the mood episode, a mood disorder with psychotic features is ruled out. Because the mood episode (3 weeks) accounts for a minority of the total illness duration (9 months), schizoaffective disorder is ruled out.
DSM-5 criteria for schizophrenia state that if mood episodes occur during the active-phase symptoms, they must be present for a minority of the total duration of the active and residual periods of the illness.

Key Concept

In a patient exhibiting both psychotic and mood symptoms, schizophrenia is diagnosed over schizoaffective disorder if the major mood episodes are present for only a minority of the total duration of the active and residual periods of the illness.
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Schizophrenia and Psychotic Disorders

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