A 55-year-old woman exhibits marked behavioral change over the past year, including impulsivity, loss of social tact, and oral exploration of objects. On examination, memory is relatively preserved and MMSE is normal. Which diagnosis is most likely?

• A. Alzheimer disease
• B. Frontotemporal dementia
• C. Pseudodementia
• D. Vascular dementia

Answer: (B)

This question centers on recognizing frontotemporal dementia when behavioral changes dominate early while memory stays relatively intact. The hallmark here is a behavioral variant: marked impulsivity, loss of social tact, and even oral exploration of objects (hyperoral behavior) with preserved memory and a normal MMSE.

In frontotemporal dementia, degeneration affects the frontal and temporal lobes, so personality, social conduct, and judgment deteriorate first. Memory may be preserved early, which explains the normal MMSE and relatively intact recall in this patient, despite dramatic changes in behavior.

This pattern helps distinguish it from Alzheimer disease, where memory impairment is the primary and earliest feature and MMSE scores typically decline early. Pseudodementia (depressive cognitive impairment) can mimic dementia, but the hallmark is a mood/personal impact rather than disinhibited, hyperoral behavior. Vascular dementia often shows a stepwise decline with focal neurological signs or imaging evidence of vascular disease, rather than early disinhibition and hyperorality.

So the most likely diagnosis, given the prominent behavioral changes with preserved memory, is frontotemporal dementia.