Cross-cultural adaptation and psychometric evaluation of the DoFEL-R for early detection of Alzheimer's related functional decline in Croatia

Background and Aims:
Early-stage Alzheimer's disease (AD) is often associated with subtle functional changes that may go undetected by conventional assessment tools. The Details of Functions of Everyday Life – Revised (DoFEL-R) was developed to address this gap by embedding updated theoretical understandings from memory binding into the assessment of everyday tasks. This study aimed to translate, cross-culturally adapt, and conduct a preliminary validation of the DoFEL-R for use with Croatian-speaking older adults.

Methods:
Following the guidelines of the International Test Commission (ITC), the adaptation process included forward and back translation, a Delphi expert panel, cognitive interviews, and pilot testing. A total of 263 community-dwelling older adults completed the Croatian DoFEL-R, with fifty-six participating in a 2-week follow-up to assess test-retest reliability.

Results:
Exploratory factor analysis supported a two-factor structure aligned with relational and conjunctive binding, consistent with the original theoretical framework. The scale showed strong internal consistency (Cronbach's α = 0.89) and excellent test-retest reliability (ICC = 0.91). Cognitive interviews indicated good face validity and cultural appropriateness of the adapted items.

Conclusion:
These findings support the Croatian DoFEL-R as a valid and reliable tool for identifying early functional decline indicative of AD-related dementia in older adults. Its use may enhance early detection of preclinical AD and inform clinical assessment practices in Croatia and similar cultural contexts. However, the sample's relatively high educational and digital literacy levels may limit generalisability, and further research is needed to confirm applicability across more diverse populations.