Abstract: ObjectiveTo explore the pattern and the time course changes of semantic and phonological processing during Chinese language cognition study in patients with mild Alzheimer's disease(AD) and mild cognitive impairment (MCI).MethodsPatients with mild AD and MCI and normal controls matched with age, gender, level of education were enrolled in the single-character words naming task, which applied short and long stimulus onset asynchrony (SOA). Semantic, homophonic, semihomophonic and unrelated primes preceded the words as well as nonwords targets. Subjects were asked to read the targets aloud. Semantic and phonological priming effects were analyzed by comparing reaction time of semantic, homophonic or semihomophonic related targets to unrelated targets. The reaction time and accuracy for each response were recorded.ResultsThe mean reaction time of mild AD and MCI patients were prolonged for all types of priming in contrast with normal controls. Responses of the normal controls were faster during the long SOA comparing to short SOA, whereas the mild AD group's reaction time was longer for long SOA than for short SOA. Normal controls exhibited homophonic priming, whereas mild AD and MCI groups exhibited tonal inhibition effects.ConclusionThe speed of Chinese language cognitive processing decreased in mild AD and MCI patients. The phonological encoding and accessing ability may be impaired in mild AD and MCI.

Key words: Alzheimer's disease (AD), mild cognitive impairment (MCI), word naming task, reaction time (RT), semantic priming