Memory Outcome in Prodromal and Mild Dementia with Lewy Bodies and Alzheimer’s Disease: A Longitudinal Study

BACKGROUND: Dementia with Lewy bodies (DLB) and Alzheimer’s disease (AD) are likely to induce memory impairments from the prodromal stage but, to our knowledge, no longitudinal study of these patients’ memory profile has been conducted to date. OBJECTIVE: The aim of our study was to describe the characteristics and the evolution of the long-term memory profile of patients with prodromal and mild DLB and AD. METHODS: We collected verbal (RL/RI-16) and visual (DMS48) memory scores from 91 DLB patients, 28 AD patients, 15 patients with both conditions (DLB/AD), and 18 healthy control subjects at their inclusion visit and at 12, 24, and 48 months. RESULTS: On the RL/RI-16, DLB patients performed better than AD patients in terms of total recall (p < 0.001), delayed total recall (p < 0.001), recognition (p = 0.031), and loss of information over time (p = 0.023). On the DMS48, differences between these two groups were not significant (p > 0.05). Longitudinally, the memory performance of DLB patients was stable over 48 months, unlike that of AD patients. CONCLUSION: Four indicators were relevant to distinguish between DLB and AD patients in terms of memory performance: DLB patients benefitted greatly from semantic cueing, their recognition and consolidation abilities were well-preserved, and both their verbal and visual memory performance remained remarkably stable over four years. However, no performance differences between DLB and AD patients were found regarding visual memory, either qualitatively (memory profile) or quantitatively (severity of impairment), indicating the lesser relevance of this test in distinguishing between these two diseases.