Author Of 1 Presentation
P0829 - The adapted Symbol Digit Modalities Test: a proof of concept study (ID 351)
Abstract
Background
Cognitive impairments, particularly information processing speed (IPS) and learning and memory, are very common in multiple sclerosis (MS), appearing both at disease onset and later in the disease. The Symbol Digit Modalities Test (SDMT) is the most commonly used test to assess IPS in MS. The SDMT has many advantages including, ease of administration, good reliability, predictive validity, sensitivity and specificity. Additionally, it is the single test common to all recommended cognitive batteries in MS. Although widely used, the SDMT has several limitations often overlooked.
Objectives
The current study examines performance on an adapted version of the SDMT (aSDMT), designed to control for learning, potential verbalization of symbols, mirror images or symbols, visual noise, and spatial working memory demands inherent with the standard SDMT, and to establish its reliability.
Methods
Performance on the aSDMT was assessed behaviorally and by examining eye movement indices with an eye tracker. Twenty-nine participants with clinically definite multiple sclerosis and fourteen healthy controls completed two versions of the aSDMT and a battery of neuropsychological tests, examining the most common cognitive deficits in MS. Differences between groups were assessed with one-way ANOVAs and test-retest reliability was assessed with Interclass Correlation Coefficient Analysis.
Results
Poorer IPS efficiency (total time to complete the aSDMT) was correlated with higher visual temporal fixation durations and more visual fixations. Eye movement indices were correlated with traditional neuropsychological tests of learning and memory and visuospatial working memory. The newly developed aSDMT showed significant correlations (total correct responses on the aSDMT r = .85, p <.01; and total time to complete the aSDMT r = .83, p <.01) with the standard SDMT and moderate to good test-retest reliability.
Conclusions
This study provides preliminary proof of concept data for the impact of visuospatial working memory, learning and memory on performance of the aSDMT, confirming the multifaceted nature of IPS efficiency.