The differentiation of semantic dementia and frontal lobe dementia (temporal and frontal variants of frontotemporal dementia) from early Alzheimer's disease: A comparative neuropsychological study

The authors compared age-matched groups of patients with the frontal and te mporal lobe variants of frontotemporal dementia (FTD; dementia of frontal t ype [DFT] and semantic dementia), early Alzheimer's disease (AD), and norma l controls (n = 9 per group) on a comprehensive neuropsychological battery. A distinct profile emerged for each group: Those with AD showed a severe d eficit in episodic memory with more subtle, but significant, impairments in semantic memory and visuospatial skills; patients with semantic dementia s howed the previously documented picture of isolated, but profound, semantic memory breakdown with anemia and surface dyslexia but were indistinguishab le from the AD group on a test of story recall; and the DFT group were the least impaired and showed mild deficits in episodic memory and verbal fluen cy but normal semantic memory. The frontal and temporal presentations of FT D are clearly separable from each other and from early AD.