Working memory binding failures and abnormal cortical neural oscillations in Alzheimer’s disease

Poster Session B - Sunday, April 14, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Emma-Jane Mallas^1,2 (e.mallas@imperial.ac.uk), Michael C.B. David^1,2, Paresh A. Malhotra^1,2, Gregory Scott^1,2, David J. Sharp^1,2; ¹Imperial College London, ²UK Dementia Research Institute, Care Research & Technology Centre

Background: Associative binding is key to normal memory function and, within dementia, is specifically impaired in Alzheimer’s disease (AD). Electrophysiological abnormalities are frequently reported in AD including during associative binding tasks. We investigated the binding of distinct visual features (object and location) in working memory in AD patients. We test the hypothesis that misbinding in AD is related to electrophysiological abnormalities, as we have shown previously in traumatic brain injury (TBI). Methods: 40 AD patients and 30 healthy age-matched controls (HC) were tested with a precision spatial working memory paradigm requiring the association of object and location information. High-density EEG was used to assess changes in power across frequency bands. Results: AD patients showed impairment in working memory function and made significantly more misbinding errors (p<0.001) than HC indicating that working memory recall was abnormally biased by the spatial locations of distractor items. AD patients demonstrated significant reductions in global alpha and increases in global theta, represented by the theta-alpha ratio (p<0.01; TAR). Channel-wise analysis revealed significant clusters of decreased power in AD across parietal channels in alpha and beta bands (p<0.01), and increase in the theta band (p<0.05) in frontal channels. In AD, TAR showed significant negative correlation with identification (p<0.01) and localisation accuracy (p<0.05). Conclusions: These results offer further support for a deficit in working memory binding being a sensitive cognitive biomarker of AD. Pathological changes to cortical neural oscillations, including increased TAR, may offer mechanistic insight into the profound working memory impairments seen in AD and TBI.

Topic Area: EXECUTIVE PROCESSES: Working memory