A physician-validated, board-style question from the Active Transport QBank. Try it, then check the reasoning for every option.
A 65-year-old man presents to his primary care physician for a change in his behavior over the past few months. Initially, the patient was noted to be behaving inappropriately including using foul language and grabbing people unexpectedly. This has progressed to a worsening of his memory and trouble caring for himself. His temperature is 98.1°F (36.7°C), blood pressure is 162/103 mmHg, pulse is 83/min, respirations are 13/min, and oxygen saturation is 98% on room air. Physical exam is notable for an elderly man who laughs inappropriately at times and who is a poor historian. When he is engaged in conversation, he exhibits word finding difficulty and is rather inattentive. Which of the following is the most likely diagnosis?
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A
Alzheimer dementiaIncorrect. Alzheimer dementia begins with anterograde memory loss and visuospatial deficits, not the upfront disinhibition and personality change seen here.
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B
Frontotemporal dementiaCorrect. Behavioral disinhibition, inappropriate affect, and language difficulty with relatively preserved early memory point to frontotemporal dementia.
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C
Kluver-Bucy syndromeIncorrect. Kluver-Bucy syndrome (bilateral amygdala lesions) features hyperorality, hypersexuality, and placidity — typically post-traumatic or post-HSV encephalitis, not a progressive dementia.
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D
Vascular dementiaIncorrect. Vascular dementia shows stepwise cognitive decline with focal neurologic findings and prior strokes — not the gradual disinhibition pattern described.
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E
Lewy body dementiaIncorrect. Lewy body dementia features visual hallucinations, parkinsonism, and fluctuating cognition — not the early behavioral disinhibition and language change seen in frontotemporal dementia.
↑ Tap an answer to reveal the reasoning
Answer: B. Early prominent behavioral disinhibition (foul language, inappropriate touching, inappropriate laughter) with relatively preserved memory at onset is the signature of behavioral-variant frontotemporal dementia (bvFTD). The disorder reflects degeneration of the frontal and anterior temporal lobes, sparing the hippocampus early on. As disease progresses, word-finding difficulty (semantic deficits), attentional decline, and finally memory loss develop — exactly the trajectory described.
Histopathology shows tau-positive Pick bodies or TDP-43 inclusions, with frontotemporal atrophy on imaging. Most cases occur in adults aged 50–70. Distinguishing bvFTD from Alzheimer disease is critical: Alzheimer's begins with anterograde memory loss and visuospatial problems, whereas bvFTD begins with personality and behavioral change. Vascular dementia would show stepwise decline with focal neurologic deficits and known cerebrovascular risk factors, and Kluver-Bucy syndrome (bilateral amygdala lesions causing hyperorality, hypersexuality, placidity) is a rare focal syndrome, not a progressive dementia.
Treatment of bvFTD is supportive — SSRIs may help disinhibition; cholinesterase inhibitors are not effective and may worsen behavior.
**Why each option:**
**A.** Alzheimer dementia begins with anterograde memory loss and visuospatial deficits, not the upfront disinhibition and personality change seen here.
**B.** Correct. Behavioral disinhibition, inappropriate affect, and language difficulty with relatively preserved early memory point to frontotemporal dementia.
**C.** Kluver-Bucy syndrome (bilateral amygdala lesions) features hyperorality, hypersexuality, and placidity — typically post-traumatic or post-HSV encephalitis, not a progressive dementia.
**D.** Vascular dementia shows stepwise cognitive decline with focal neurologic findings and prior strokes — not the gradual disinhibition pattern described.