What makes music memorable in Alzheimer’s disease? Valence dependency in relationships between music, emotions and memory

Music can be a powerful tool for evoking emotions and memories in Alzheimer’s disease (AD) and is commonly used in dementia care. Previous research suggests that memories evoked by music tend to vary depending on the experienced valence (pleasant vs. unpleasant) of the songs, show a reminiscence bump (RB) for events from mid-childhood/adolescence, and are linked to certain musical features, such as rhythm, in healthy older adults, but little is known about factors underlying music-evoked memories in AD. In the present study, we used a combination of behavioural ratings of emotional valence, familiarity, and autobiographical salience and musical features analyzed using music information retrieval (MIR) from 70 excerpts of traditional folk songs and popular music from 1950s to 1970s in healthy older adults (n = 40) and persons with mild (n = 29) and moderate/severe (n = 32) dementia to explore how emotional and memory experience of music, valence dependency of musical memories as well as the temporal gradient of the RB and predictive musical features of musical memories change from healthy ageing to advanced AD dementia. Compared to healthy older adults, we observed lower familiarity and autobiographical salience but comparable valence in the AD groups as well as increasingly linear relationship between valence and familiarity and autobiographical salience with advancing AD. Also the temporal gradient (RB) became steeper with advancing AD, peaking earlier in childhood. From musical features, less complex harmonicity predicted higher autobiographical salience and less strong pulse predicted higher familiarity across groups, but this latter relationship showed stronger valence dependency in AD. In conclusion, our findings provide novel insights on how factors associated with music-evoked memories change in the progression of AD, showing differential relationships from healthy ageing to advanced AD. The results can be beneficial in dementia care by helping in individualizing music interventions.