Normative Data for the D-KEFS Tower Test in Greek Adult Population Between 20 and 85 Years Old.

Background: The Delis-Kaplan Executive Function System (D-KEFS) Tower Test (TT) is a widely used neuropsychological tool that assesses complex executive functions, including planning, cognitive flexibility, inhibition, switching, and impulsivity-key abilities often impaired in individuals with frontal dysfunction. Aims: There is currently no normative data for the D-KEFS TT in the Greek population. Consequently, it cannot be effectively used to detect executive dysfunction in neurological and psychiatric populations or for research purposes. Methods: The study sample included 249 healthy adults (28.9% male, 71.1% female) aged 20 to 85 years (M = 46.53, SD = 17.41), with educational levels ranging from secondary school graduates to master's degree holders. Pearson correlation was used to examine the relationship between age and D-KEFS TT performance, while chi-square test assessed the effects of education and gender. Normative data were then derived from raw scores and converted into percentiles. Results: Norms were established for the following D-KEFS TT variables: Total Achievement Score, Total Rule Violations, Move Accuracy Ratio, Mean First Move Time, and Time-per-Move Ratio. Age was the strongest predictor of performance, and normative data were stratified accordingly for the Greek adult population. Conclusions: This study introduces the D-KEFS TT as a neuropsychological assessment tool for Greek adults across different age groups to evaluate complex executive functions throughout the lifespan. Unlike other D-KEFS tests, the TT had not previously been adapted for the Greek population. This study is the first to provide normative data, supporting its use in clinical practice and research.