Normative data of the coding test in Korean middle-aged and elderly population

BACKGROUND: The Coding (CD) subtest is widely recognized as a sensitive and reliable measure of age-related cognitive decline, particularly in processing speed, which is known to be vulnerable in the early stages of Alzheimer's disease. However, normative data for middle-aged and older Korean adults, who exhibit wide variability in educational backgrounds, remain limited. Establishing norms that reflect this demographic diversity is essential for accurate cognitive assessment and interpretation. OBJECTIVE: This study aimed to examine the effects of age, education, and gender on CD performance in cognitively unimpaired Korean adults aged 50 years and older, and to establish normative data for the Korean aging population. METHODS: A total of 534 cognitively unimpaired adults aged 50 to 92 years participated. The CD subtest was administered following standardized procedures. Analysis of variance and hierarchical multiple linear regression analyses were performed to examine the demographic effects on CD performance. RESULTS: Younger age and higher education were associated with better CD performance, with a significant age-by-education interaction, while gender did not show a significant effect. Accordingly, normative data were established for three age groups (50-59, 60-74, and ≥75 years) and three education levels (0-8, 9-12, and ≥13 years). CONCLUSIONS: The normative data presented in this study provide a valuable reference for clinicians and researchers to more accurately evaluate processing speed abilities in middle-aged and older Korean adults.