Semantic impairment in very early Alzheimer disease

Abstract

AbstractBackgroundComparing to episodic memory, semantic memory is less likely to be impaired in normal aging. Investigation of semantic memory may give us a better chance on detecting Alzheimer disease in early stage.MethodIn 2019, we collected 20 patients from our memory clinic. Half of them were diagnosed as amnesic MCI (mild cognitive impairment), half of them were their spouse. All of them received amyloid PET (florbetaben), brain MRI, ERP (evoked related potential) studies and detailed language evaluation. According to their clinical symptoms and status of amyloid deposition, they were grouping as normal, preclinical and prodromal stage.ResultIn picture description test, participants of prodromal group expressed fewer semantic contents and more filler words compared to others. No significant difference was found between preclinical and normal group. However, N400 (component of ERP, indicating semantic mismatch) showed difference between preclinical and normal group.ConclusionSemantic network impairment begins from preclinical stage of AD. Through detailed spoken language analysis, we could use it as early biomarker and trace disease progression.