In the evaluation of the nature of naming disorders, there is a rapid increase of anomia with the progression of Alzheimer's disease (AD), which is associated with whole brain atrophy. Although numerous studies have investigated this naming disorder, there is limited information on naming procedures in these patients. Reaction time (RT) is highly sensitive to dementia and provides an accurate measurement. The present study investigated the RT of each underlying level of naming in patients with mild AD and identified the nature of anomia in these patients. The study consisted of 24 healthy elderly and 22 mild AD patients who participated in experiments that were designed for evaluating each level of Levelt's model. Responses were divided into three groups of correct, false, and no-response and their RTs were calculated. The statistical analyses showed significant differences between healthy elderly and patients with mild AD in terms of access to the concept and the phonological form of the words. Moreover, significant differences in the type of responses were observed between correct and false responses of both groups. There was a significant difference between the no-response cases except in the case of lemma access for singular and plural names in other tasks. The results suggest that patients with mild AD have problems at the conceptual stage and access to the phonological form of a word.
Keywords: Alzheimer; conceptual preparation; lemma; morphological encoding; naming; phonological encoding; reaction times.