A novel episodic memory test optimized for smart phone high-frequency assessments.

Abstract

Decline in episodic memory is a strong marker of neurodegenerative diseases, making it an important target for cognitive assessment. We present a new remote, repeatable, and brief assessment of episodic memory and visual short-term memory (VSTM) for smart phone deployment. We evaluated this task for sensitivity to age and established cognitive measures of memory and attention. The task consists of a learning phase where participants see a sequence of items, then are asked to replicate the item order and location by dragging and dropping these items on-screen. A recall phase follows a minimum 12-hour delay, with replication of the earlier response. Each session takes less than 2 minutes. The first phase supplies metrics of spatial and order precision VSTM, with the second phase characterising long-term episodic memory. Experiment 1 (n=133) compares the task with CANTAB assessments of visuospatial memory. In Experiment 2 (n=80) the novel task was repeated twice daily for a week, alongside momentary mood ratings, and a more comprehensive battery of CANTAB tasks at baseline. In Experiment 1, multiple regression and dominance analyses explore the independent and shared variance of measures in explaining age. In Experiment 2, clustering and multivariate autoregressive models outline differences in timeseries relationships between mood and memory, and age. Experiment 1 revealed that CANTAB measures and novel spatial and order metrics were correlated with age (r=.20 to r=.37, adjusted P= <.05). Multiple regression showed models with CANTAB Paired Associate Learning (PAL) score, and delayed novel spatial metrics were significantly predictive of age (t= -4.08, 3.17, p <.005). The dominance analysis revealed novel immediate precision overlapped with existing measures in predicting Age, while delayed precision had more unique variance (4.6% vs 0.62% unique sample variance explained in Age, accounting for PAL). Experiment 2 characterised variance in individual learning curves over time and differing autoregressive processes associated with age and CANTAB measures. We present a brief novel episodic memory task that can be deployed remotely, with delayed spatial precision significantly predictive of healthy Ageing. Additionally, we show this test's suitability as a repeated assessment, compatible with high-frequency study designs in older populations.