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Difficulty: MediumNeurocognitive Disorders

A 54-year-old man is brought to the outpatient psychiatry clinic by his wife due to a 4-month history of significant behavioral changes. Previously known as a quiet and highly professional bank manager, he has recently become excessively blunt, apathetic, and socially disinhibited. Last week, he made explicit sexual remarks to a neighbor and was reprimanded at work for taking food directly off a colleague's desk. He has no prior psychiatric history. His medical history includes hypertension and hyperlipidemia. He currently takes lisinopril and atorvastatin; he also recently started occasionally taking his wife's fluoxetine. Vital signs are within normal limits. Laboratory results, including a complete blood count, comprehensive metabolic panel, and a normal thyroid-stimulating hormone (TSH) level, are unremarkable. On mental status examination, he is alert and fully oriented. His short-term memory recall is intact, but he demonstrates significant impairments on the trail-making test and verbal fluency tasks. Which of the following is the most likely diagnosis?

  1. A
    Major depressive disorder
  2. B
    Schizophreniform disorder
  3. Frontotemporal dementiaAnswer
  4. D
    Hypothyroidism
  5. E
    Serotonin syndrome

Answer

Frontotemporal dementia
The most likely diagnosis is frontotemporal dementia (FTD), specifically the behavioral variant. FTD typically presents in patients between the ages of 50 and 60. The classic clinical picture involves early and profound changes in personality and behavior, including social disinhibition (e.g., inappropriate sexual remarks), apathy, loss of empathy, and hyperorality (e.g., taking food from others). Cognitive testing typically reveals prominent executive dysfunction (impaired trail-making and verbal fluency) with relatively preserved memory and visuospatial skills early in the disease course. The absence of a prior psychiatric history in a middle-aged patient with these specific behavioral changes makes a neurocognitive disorder highly likely.

Step-by-Step Solution

1
Analyze the patient's demographic and primary symptoms.
A 54-year-old man presenting with new-onset apathy, social disinhibition, and hyperorality over 4 months.
To establish the core clinical syndrome and rule out lifelong psychiatric conditions.
2
Evaluate the cognitive testing and laboratory results.
Intact short-term memory but impaired executive function (trail-making, verbal fluency); normal TSH.
To differentiate cortical vs. subcortical, and frontal vs. temporal/parietal neurocognitive deficits, and to rule out reversible medical causes like hypothyroidism.
3
Synthesize the findings to determine the most likely etiology.
Early-onset personality changes with prominent executive dysfunction and preserved memory strongly indicate the behavioral variant of a primary neurocognitive disorder, differentiating it from pseudodementia.
To arrive at the final diagnosis of frontotemporal dementia.

Key Concept

The behavioral variant of frontotemporal dementia classically presents in patients aged 50-60 with early personality changes, social disinhibition, apathy, and executive dysfunction, while memory and visuospatial skills remain relatively intact early in the disease course.
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Topics

Neurocognitive Disorders

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