Nonoptic aphasia: aphasia with preserved confrontation naming in Alzheimer's disease.

Patients with Alzheimer's disease (AD) frequently exhibit anomia early in the course of the disease. Current theories of naming describe lexical retrieval in visual confrontation naming as requiring processing through the semantic system before lexical access. We report on three patients with AD who demonstrated severely impoverished spontaneous speech, impaired list generation, but preserved visual confrontation naming. Extensive investigation of one of these patients revealed an impairment of semantic knowledge. Our results support previous theories that there are two routes to visual naming, one via the semantic system and one directly from the internal visual representation to the lexicon. We labeled this aphasia resulting from an impaired semantic system but a preserved direct route to the lexical system as "nonoptic aphasia" and suggest that it is the earliest language deficit in some patients with AD.