Houot, M. | bioRxiv Science

bioRxiv2023

Sensorimotor Impairment in Ageing and Neurocognitive Disorders: Beat Synchronisation and Adaptation to Tempo Changes

BackgroundUnderstanding the nature and extent of sensorimotor decline in ageing individuals and those with neurocognitive disorders NCD, such as Alzheimers disease, is essential for designing effective music-based interventions. ObjectiveOur understanding of rhythmic functions remains incomplete, particularly in how ageing and NCD affect sensorimotor synchronisation and adaptation to tempo changes. This study aims to fill this knowledge gap. MethodsPatients from a memory clinic participated in a tapping task, synchronising with metronomic and musical sequences, some of which contained sudden tempo changes. After exclusions, 51 patients were included in the final analysis. ResultsParticipants mini-mental state examination scores were associated with tapping consistency. Additionally, age negatively influenced consistency when synchronising with a musical beat, whereas consistency remained stable across age when tapping with a metronome. ConclusionsThe ability to extract a beat from a musical signal diminishes with age, whereas the capacity to maintain a beat remains relatively constant. However, both processes may decline at moderate or severe stages of NCD. Moreover, the results indicate that the initial decline of attention and working memory with age may impact perception and synchronisation to a musical beat, whereas progressive NCD-related cognitive decline results in more widespread sensorimotor decline, affecting tapping irrespective of audio type. These findings underline the importance of customising rhythm-based interventions to the needs of older adults and individuals with NCD, taking into consideration their cognitive as well as their rhythmic aptitudes. This study was registered at clinicaltrials.gov (NCT04146688).

neuroscience↗

bioRxiv2022

Why Are Alzheimer's Disease Patients Unaware of their Memory Deficits?

Anosognosia, or the lack of awareness of ones own impairment, is frequent for memory deficits in patients with Alzheimers disease (AD). Although often related to frontal dysfunctions, the neural mechanisms of anosognosia remain largely unknown. We hypothesized that anosognosia in AD may result from a failure in the error-monitoring system, thus preventing patients from being aware of and learning from their own errors. We therefore investigated the event-related potentials evoked by erroneous responses during a memory task in two groups of amyloid positive individuals who had only subjective memory complaints at study entry: 1) those who progressed to AD; and 2) those who remained cognitively normal after five years of follow-up. Our findings revealed direct evidence of a failure in the error-monitoring system at early stages of AD, suggesting that it may be the critical neural substrate of anosognosia in this neurodegenerative disorder.

neuroscience↗