Short-term memory binding and semantic network strength reinforce prospective memory in older adults

Paster, Mollie and Parra Rodriguez, Mario and Salmon, David P. and Jacobs, Diane M. (2019) Short-term memory binding and semantic network strength reinforce prospective memory in older adults. In: International Neuropsychological Society 47th Annual Meeting, 2019-02-20 - 2019-02-23, Marriott Hotel.

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Abstract

Objective Prospective memory (Pro-M), or remembering to carry out a future task, is critical to everyday functioning, but is not assessed by traditional neuropsychological measures. In this study, we investigated neurocognitive mechanisms underlying Pro-M ability in older adults. Participants and Methods 48 nondemented older adults (M age=75.2; SD=2.1) were recruited from the UCSD Alzheimer’s Disease Research Center (ADRC). Participants were 60% female and averaged 17.2 years (SD=2.1) of education. The Memory for Intentions Screening Test (MIST; Raskin et al., 2010) and a visual short-term memory (STM) binding task (Parra et al., 2017) were administered in a single session. Results were compared with scores on traditional neuropsychological measures from a recent ADRC annual assessment. Results Overall performance on the MIST was significantly correlated with shape-color binding accuracy (r=0.38; p<0.05) and Animal Fluency (r=0.29; p<0.05), but was not associated with traditional tests of episodic memory (e.g., CVLT, Logical Memory) or executive functioning (e.g., WCST, Trails B) (all p values > 0.10). Analysis of errors on MIST time-cued tasks revealed the most common error was performing an incorrect task at the prescribed time (61%), whereas performing the prescribed task at the incorrect time was relatively infrequent (13%). Conclusions Performance of non-demented older adults on Pro-M was associated with STM binding and category fluency but not episodic memory or executive functioning. These results suggest that Pro-M is a unique aspect of memory functioning that is distinct from episodic memory and requires synthesizing multiple cognitive strategies. Participants with a stronger semantic network may be able to create a strong association for the intention at the time of encoding, while Pro-M failures could be explained by a failure to adequately bind the semantic components of the encoded intention and the future action.

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