Is knowledge of famous people disproportionately impaired in patients with early and questionable Alzheimer's disease?

Twenty-two patients with early dementia of Alzheimer's type (DAT) and 31 controls were administered tests of person-specific semantics (Experiment 1). DAT patients were impaired on all test components. In Experiment 2, 31 DAT patients, 28 questionable DAT (QDAT) patients, and 42 controls were administered the Graded Naming Test (GNT) and the newly designed Graded Faces Test (GFT), matched for difficulty with the GNT. DAT patients were impaired throughout but showed an advantage for naming objects over faces. The QDAT patients were impaired on the GFT only. Of the 7 QDAT patients who evolved to DAT within 1-2 years, 6 showed initial impairment on the GFT, whereas 17 of the nonconverters scored normally on the GFT. Results suggest greater and earlier vulnerability of person knowledge than general semantic knowledge in DAT.