Normative data of the digit span test for the Turkish population aged between 50 and 83 years

Abstract

Objectives: This study aimed to determine normative values stratified by age, education, and sex for the digit span test (DST), a commonly used tool for assessing attention, short-term memory, and working memory in Türkiye, in the Turkish population aged 50 and above. Patients and methods: A total of 340 healthy individuals (139 males, 201 females; mean age 64.4±8.5; range, 50 to 83 years) were included in the study, stratified by age (three levels: 50-59 years, 60-69 years, 70-83 years), education (three levels: 0-5 years, 6-11 years, 12 years and above), and sex (female, male) variables. The participants’ longest digit span forward (DSF), digit span backward (DSB) scores and total DST scores were included in the analyses. The relative contributions of age, education, and sex variables to DST scores were examined using multiple linear regression analysis, while their main effects and interaction effects were investigated using a 3×3×2 ANOVA design. Test-retest reliability of the DST was determined by tests administered in 12-month intervals. Results: Demographic variables accounted for 25 to 38% of the variance in the longest DSF and DSB scores and total DST scores. Significant main effects of age, education, and sex were observed on the longest DSF scores and total DST scores, while only age and education had main effects on the longest DSB scores. The DST demonstrated strong test-retest reliability. Conclusion: This study established normative values for the DST subscores for individuals aged 50-69 and 70-83 years with low, moderate, and high levels of education. Notably, years of education emerged as the strongest predictor of DST performance. Overall, advanced age, lower educational attainment, and female gender were associated with reduced DST performance.