Five Digit Test in neuropsychological assessment of working memory in aged individuals:normative data

Five Digit Test (FDT) is an executive function assessment tool designed to be used across the lifespan, from children to the aged.

To provide validity evidence for FDT in the neuropsychological assessment of working memory in the aged.

A total of 100 subjects, aged between 56 and 86 years, representing both genders with varying levels of education, underwent a comprehensive clinical history and neuropsychological evaluation using FDT. The mean age of participants was 71.04 years, with 67.3% having intermediate education. Participants were categorized into two groups: Control Group and Cognitive Decline Group. To establish validity evidence, FDT scores (both time and errors) were correlated with the WAIS-III Digits scale. Spearman's correlation coefficient and ROC curve methodology were employed to determine psychometric properties.

A significant and moderate negative correlation was evident between FDT Shifting (number of errors) and Digits score (rho=-0.51; p<0.0001), Direct Order (rho=-0.39; p<0.0001), and Indirect Order (rho=-0.46; p<0.0001). The area under the curve was higher for FDT Shifting (errors) (AUC=0.935) for a cutoff point greater than or equal to 5 points, compared to Digits (AUC=0.748).

The assessment of the number of errors in FDT Shifting appears to be a statistically significant tool for evaluating working memory impairment in the aged.