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Case 31 - Does a Positive Amyloid Scan Always Mean Alzheimer Disease?

from Part 7 - Misinterpreting Test Results

Published online by Cambridge University Press:  03 November 2020

Keith Josephs
Mayo Clinic Alzheimer’s Disease Research Center
Federico Rodriguez-Porcel
Medical University of South Carolina
Rhonna Shatz
University of Cincinnati
Daniel Weintraub
University of Pennsylvania
Alberto Espay
University of Cincinnati
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This 72-year-old left-handed man presented with a 3-year history of cognitive and behavioral decline. His wife first noticed that he was slower to respond and make decisions. He daydreamed and often lost his focus, requiring that comments be repeated. Worsening of symptoms prompted a neurological evaluation within a year of symptom onset. The neurological exam was reported as unremarkable. The score on the Montreal Cognitive Assessment (MoCA) was 24/30 due to impairments in trail making, cube and clock drawings, phonemic fluency, and delayed recall (he recalled three words freely and recognized the other two when multiple choices were given). Brain MRI showed diffuse atrophy. Florbetapir beta-amyloid PET scan was positive by clinical read (Figure 31.1). This led to a diagnosis of Alzheimer disease.

Common Pitfalls in Cognitive and Behavioral Neurology
A Case-Based Approach
, pp. 99 - 102
Publisher: Cambridge University Press
Print publication year: 2020

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