Digit Span Test: Normative data for Turkish population aged 50 years and older

Digit Span Test (DST) is a widely-used neuropsychological test in the assessment of attention and working memory, which consists two sections, forward and backward span. DST has two scoring methods. The total forward and backward scoring method has been previously standardized for the Turkish population under the BILNOT battery. However, the maximum (longest) forward and backward span scoring is frequently used in Turkey without available normative data. This normative study included 340 healthy participants aged between 50-83 years, stratified by age, education, and gender. Multiple linear regression analysis was used to assess the relative contributions of age, education and gender on DST scores. 3x3x2 ANOVA design was used to examine the main and interaction effects of these demographic variables. Age and education were accounted for the forward, backward and total DST scores and the ANOVA revealed main effects on the same test scores. Further analyses showed significant differences between all educational groups. However, there were no significant differences between the 50-59 and 60-69 age groups on any test score. Therefore, the normative data were established for the 50-69 and 70-83 age groups. Gender was accounted for the forward and total DST scores and the ANOVA showed a main effect of gender on the same test scores. The normative data for the forward, backward and total DST scores were stratified by gender. In conclusion, this study provided the stratified normative data of the maximum forward/backward span for healthy individuals aged 50-83 years, that can be used in clinical and research settings.