Semantic and letter category naming in Alzheimer's patients: A predictable difference

Abstract

Performance on semantic and letter category naming tasks of 32 Alzheimer's disease (AD) patients from the University of California, San Diego (UCSD) Alzheimer's Disease Research Center was analyzed and compared to performance on a variety of other neuropsychological tasks. Although demonstrated to be highly correlated and equally difficult, the two generative naming tasks yielded predictably different performances. The difference score, obtained by subtracting semantic category naming scores from letter category naming scores, was best predicted in stepwise linear multiple regression by Trail Making B and Dictation. We argue that the critical difference between the two tasks is the subsystem of secondary memory on which each relies.