New Long-Term Encoding in Severely Amnesic Alzheimer's Disease Patients Revealed Through Repeated Exposure to Artistic Items.

BACKGROUND: Encoding of new information is considered to be impossible in people with Alzheimer's disease (PWAD) at a moderate to severe stage. However, a few case studies reported new learning under special circumstances, especially with music. OBJECTIVE: This article aims at clarifying PWAD's learning capacities toward unknown material under more ecological settings, which is repeated exposure without encoding instruction. METHODS: Twenty-three PWAD (Age: m = 84.6(5.2), 5≤MMSE≤19) underwent presentations of unknown artistic pieces (targets) through 8 daily individual sessions. These sessions were followed by a test session, during which their knowledge of the targets was assessed through a verbal and behavioral scale (the sense of familiarity scale) against a series of unknown items (distractors). RESULTS: Through this design, we were able to objectify encoding of three types of targets (verses, paintings, and music) against distractors the day after exposure sessions, and 2 months after the last presentation (study 1). Music and paintings were eventually well-encoded by most participants, whereas poems encoding was poorer. When compared to distractors, target items were significantly better recognized. We then compared the recognition of target paintings against two types of painting distractors, either perceptually or semantically related (study 2). The targets were better recognized than all three painting distractors, even when they were very close to the targets. CONCLUSION: Despite massive anterograde amnesia, our results clearly showed that recognition-based learning without conscious memory of the encoding context is preserved in PWAD at a severe stage, revealed through an increasing sense of familiarity following repeated exposure. These findings could open new perspective both for researchers and clinicians and improve the way we understand and care for PWAD living in healthcare facilities.

[Musical long-term memory throughout the progression of Alzheimer disease]. / La mémoire musicale à long terme au cours de l'évolution de la maladie d'Alzheimer.

In Alzheimer patients with a solid musical background, isolated case-reports have reported the maintenance of remarkable musical abilities despite clear difficulties in their verbal memory and linguistic functions. These reports have encouraged a number of scientists to undertake more systematic studies which would allow a rigorous approach to the analysis of musical memory in Alzheimer patients with no formal musical background. Although restricted in number, the latest data are controversial regarding preserved musical capacities in Alzheimer patients. Our current review of the literature addresses this topic and advances the hypothesis that the processes of musical memory are function of illness progression. In the earlier stages, the majority of evaluations concerned musical episodic memory and suggested a dysfunction of this memory whereas in the moderate and severe stages, musical semantic memory and implicit learning are the majority of investigations and seemed more resistant to Alzheimer disease. In summary, our current review bring to understand the memory circuits involved and highlight the necessity to adapted the investigational tools employed to conform with the severity of the signs and symptoms of progressive Alzheimer disease in order to demonstrate the preserved musical capacities.