Serial position effects rapidly distinguish Alzheimer's from frontotemporal dementia

A significant proportion of patients with behavioural variant frontotemporal dementia (bvFTD) show memory impairments similar to patients with Alzheimer's disease (AD), making them prone to misdiagnosis in early disease stages. Our objective was to establish a rapid and efficient memory measure that enhances discrimination between patients with dementia due to Alzheimer's disease and amnestic presentations of behavioural variant frontotemporal dementia.

Word list learning data of patients with diagnoses of AD and both amnestic and non-amnestic presentations of bvFTD were analysed. The overall recall rate and the relative contributions of the first two (primacy items) and last two words (recency items) to recall performance were compared between groups.

Overall recall rate was indistinguishable between patients with AD and amnestic bvFTD. However, AD patients' recall was mostly driven by recency items, whereas amnestic bvFTD patients' performance was mostly driven by primacy items.

We conclude that obtaining a simple recency dominance index from a single, 15-item word list memory trial can help discriminate patients with AD from patients with bvFTD, even if they present with similarly severe memory impairment.