The spectrum of category effects in object and action knowledge in dementia of the Alzheimer's type

The validity and origin of category effects in the anomia demonstrated by i ndividuals with dementia of the Alzheimer's type (DAT) remains controversia l. Twenty DAT subjects were tested with picture naming and semantic associa tion judgment tests. Picture and word stimuli were drawn from biological, n onbiological, and actions-verbs categories, all of equal difficulty and pre viously normed on elderly controls. DAT subjects made significantly more na ming and semantic judgment errors in the biological category than in the no nbiological category. They were relatively more accurate in naming and maki ng judgments for actions-verbs when presented as words or as 5-s animations . When line drawings of actions were shown for naming, performance deterior ated significantly. Converging results from these 2 tasks provide strong ev idence for a semantic memory impairment preferentially affecting biological items to a greater extent than nonbiological items or action verbs in DAT.