Effects of lexical-semantic treatment on memory in early Alzheimer disease: an observer-blinded randomized controlled trial

Abstract

Background: Episodic memory and semantic abilities deteriorate early in Alzheimer disease (AD). Since the cognitive system includes interconnected and reciprocally influenced neuronal networks, the authors hypothesized that stimulation of lexical-semantic abilities may benefit semantically structured episodic memory.

Objective: To investigate the effects of lexical-semantic stimulation (LSS) on verbal communication and episodic memory in early AD.

Methods: Forty AD participants were randomized to LSS or unstructured cognitive stimulation (UCS) as control condition. Treatments lasted 3 months, 2 sections a week. The primary outcome measures were the Mini-Mental State Examination (MMSE), Boston Naming Test (BNT), Verbal Naming Test (VNT), Phonemic and Semantic Fluency, Story Recall, and Rey Auditory Verbal Learning (RAVL). Secondary outcome measures were neuropsychological tests assessing cognitive functions not stimulated by the intervention, such as attention, executive functions, and visual-spatial abilities, and the instrumental activities of daily living scale. A 6-month follow-up assessment was administered to the LSS group.

Results: LSS treatment yielded significant improvements of the MMSE, BNT, VNT, Brief Story Recall, and RAVL delayed recall mean scores. Among secondary outcome measures, only working memory and the speed of a task assessing executive functions (Stroop test) improved after LSS. Unstructured cognitive stimulation intervention did not improve any cognitive domain. Six months after LSS discontinuation, the MMSE mean score remains significantly higher than the baseline value.

Conclusion: LSS treatment may improve episodic memory in AD patients and may be regarded as a clinical option to counteract the cognitive decline typical of the disease.