Abstract
Alzheimers Dement. 2023 Dec;19 Suppl 18:e080017. doi: 10.1002/alz.080017.
ABSTRACT
BACKGROUND: Associative binding is key to normal memory function and is selectively impaired in Alzheimer's disease (AD).1 Electrophysiological abnormalities are frequently reported in AD including during tasks requiring associative binding.2 We use a precision spatial working memory test to investigate the binding of distinct visual features (object and location) in working memory in AD patients and test the hypothesis that misbinding is related to electrophysiological abnormalities.
METHODS: 36 AD patients and 29 healthy age-matched controls (HC) were tested with a precision working memory paradigm that required the association of object and location information (Fig 1A). Participants were excluded if they were unable to perform the identification element of the task significantly above chance level (p>0.05). High-density eyes-closed resting-state EEG was used to assess changes in electrophysiological power across frequency bands.
RESULTS: 25 AD and all HC performed above chance level (Fig 1C). AD patients showed abnormalities in working memory function and made significantly more misbinding errors (p<0.001) than HC (Fig1E) indicating that working memory recall was abnormally biased by the spatial locations of distractor items (Fig 1F). AD patients demonstrated significant reductions in global alpha and increases in global theta (Fig 2A). Channel-wise analysis revealed significant clusters of decreased power in AD across occipital-parietal channels in alpha and beta bands (p<0.05; Fig 2C). Misbinding errors significantly correlated with alpha power in AD but not HC (p<0.05; Fig 2D).
CONCLUSIONS: These results offer further support for a deficit in working memory binding being a sensitive cognitive biomarker of AD. Pathologically reduced alpha power may offer mechanistic insight into the profound working memory binding impairments seen in AD. References: 1. Della Sala S, Parra MA, Fabi K, Luzzi S, Abrahams S. Short-term memory binding is impaired in AD but not in non-AD dementias. Neuropsychologia. 2012;50(5):833-840. https://doi.org/10.1016/j.neuropsychologia.2012.01.018 2. Han Y, Wang K, Jia J, Wu W. Changes of EEG Spectra and Functional Connectivity during an Object-Location Memory Task in Alzheimer's Disease. Front Behav Neurosci. 2017;11:107. https://doi.org/10.3389/fnbeh.2017.00107.
PMID:39112072 | DOI:10.1002/alz.080017
UK DRI Authors
