Validation of a digit symbol substitution test for use in supervised and unsupervised assessment in mild Alzheimer's disease. Issue 10 (26th November 2022)

• Record Type: Journal Article
• Authors: Williamson, Michael; Maruff, Paul; Schembri, Adrian; Cummins, Hannah; Bird, Laura; Rosenich, Emily; Lim, Yen Ying
• Is Part Of: Journal of clinical and experimental neuropsychology. Volume 44:Issue 10(2022)
• Page Start: 768
• Page End: 779
• Publication Date: 2022-11-26
• Subjects: Cognitive assessment -- Alzheimer's disease -- unsupervised assessment -- Digit-Symbol-Substitution -- neuropsychology; Neuropsychology -- Periodicals; Psychophysiology -- Periodicals; Neurosciences -- Periodicals; Psychophysiology -- Periodicals; Societies, Medical -- Periodicals; 616.89
• DOI: 10.1080/13803395.2023.2179977
• Languages: English
• ISSNs: 1380-3395

Abstract

ABSTRACT: Introduction: The Digit-Symbol-Substitution Test (DSST) is used widely in neuropsychological investigations of Alzheimer's Disease (AD). A computerized version of this paradigm, the DSST-Meds, utilizes medicine-date pairings and has been developed for administration in both supervised and unsupervised environments. This study determined the utility and validity of the DSST-Meds for measuring cognitive dysfunction in early AD. Method: Performance on the DSST-Meds was compared to performance on the WAIS Coding test, and a computerized digit symbol coding test (DSST-Symbols). The first study compared supervised performance on the three DSSTs versions in cognitively unimpaired (CU) adults (n = 104). The second compared supervised DSST performance between CU ( n = 60) and mild-symptomatic AD (mild-AD, n = 79) groups. The third study compared performance on the DSST-Meds between unsupervised ( n = 621) and supervised settings. Results: In Study 1, DSST-Meds accuracy showed high correlations with the DSST-Symbols accuracy ( r = 0.81) and WAIS-Coding accuracy ( r = 0.68). In Study 2, when compared to CU adults, the mild-AD group showed lower accuracy on all three DSSTs (Cohen's d ranging between 1.39 and 2.56) and DSST-Meds accuracy was correlated moderately with Mini-Mental State Examination scores ( r = 0.44, p < .001). Study 3 observed no difference in DSST-meds accuracy between supervised and unsupervised administrations. Conclusion: The DSST-Meds showed good construct and criterion validity when used in both supervised and unsupervised contexts and provided a strong foundation to investigate the utility of the DSST in groups with low familiarity to neuropsychological assessment.