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Difficulty: Very hardSchizophrenia and Psychotic Disorders

A 42-year-old man is evaluated in the outpatient psychiatry clinic at the insistence of his husband. For the past 8 months, the patient has been absolutely convinced that a rival accounting firm has hacked his home network and is monitoring his digital footprint. Consequently, he has disconnected the home Wi-Fi and sweeps the house weekly for hidden listening devices. Despite these behaviors at home, the patient continues to excel as a senior accountant at his firm, socializes appropriately with peers, and exhibits a normal, reactive affect with no evidence of disorganized speech or hallucinations.

Two months ago, the patient developed a pervasively depressed mood, early morning awakenings, anhedonia, and a 4-kg (9-lb) weight loss. He stated he felt "hopeless about ever regaining my privacy." These mood symptoms lasted for exactly 3 weeks before completely resolving after he purchased a sophisticated electronic signal jammer. He currently reports feeling emotionally well but remains convinced of the ongoing surveillance. Physical examination and urine toxicology screens are unremarkable. Which of the following is the most likely diagnosis?

  1. Delusional disorderAnswer
  2. B
    Schizoaffective disorder, depressive type
  3. C
    Schizophrenia
  4. D
    Major depressive disorder with psychotic features
  5. E
    Paranoid personality disorder

Answer

Delusional disorder
The correct diagnosis is delusional disorder. This diagnosis requires the presence of one or more delusions for a duration of 1 month or longer. Crucially, the patient must never have met Criterion A for schizophrenia (which requires at least two psychotic symptoms such as delusions, hallucinations, disorganized speech, or negative symptoms). This patient has isolated delusions without any other psychotic features. Additionally, in delusional disorder, functioning is not markedly impaired apart from the direct ramifications of the delusion, as demonstrated by this patient's continued success at work and social engagement. Finally, if major depressive episodes occur concurrently with the delusions, their total duration must be brief relative to the duration of the delusional periods. This patient's 3-week depressive episode is appropriately brief compared to his 8-month history of delusions.

Step-by-Step Solution

1
Assess whether the patient meets Criterion A for schizophrenia.
The patient has only one psychotic symptom (delusions) and lacks hallucinations, disorganized speech, or negative symptoms. Therefore, he does not meet Criterion A for schizophrenia.
This immediately rules out both schizophrenia and schizoaffective disorder, which strictly require meeting Criterion A.
2
Evaluate the timeline of the mood symptoms relative to the psychotic symptoms.
The patient experienced a 3-week major depressive episode embedded within an 8-month period of continuous delusions.
Because the delusions exist outside the mood episode, major depressive disorder with psychotic features is ruled out. Furthermore, DSM-5 criteria for delusional disorder specify that if mood episodes occur, their total duration must be brief relative to the total duration of the delusional periods (3 weeks is brief compared to 8 months).
3
Assess the patient's overall level of functioning.
Apart from the direct impact of the delusion (sweeping for bugs), the patient's functioning is not markedly impaired; he continues to excel at work and socialize normally.
Preserved psychosocial functioning in the presence of a fixed, non-bizarre delusion strongly points to delusional disorder, finalizing the diagnosis.

Key Concept

Delusional disorder requires the presence of one or more delusions for at least 1 month, failure to meet Criterion A for schizophrenia, relatively preserved psychosocial functioning, and any concurrent mood episodes must be brief relative to the total duration of the delusions.
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Topics

Schizophrenia and Psychotic Disorders

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