Examining the Cognitive Underpinnings of Functional Decline in Prodromal Alzheimer's Disease: Insights From the Details of Functions of Everyday Life (DoFEL) Scale.

Available assessments for early-stage Alzheimer's disease (AD) identify neuropsychological and functional impairments, which rarely correlate in the early disease stages. The ability to bind information in memory declines in preclinical AD stages. However, it is unclear whether such cognitive deficits underlie functional impairment in prodromal AD stages. This study investigates whether incorporating memory binding, a function that is a sensitive cognitive marker for early-stage AD, into a functional assessment tool can reveal the cognitive underpinnings of daily activities. The Details of Function of Everyday Life (DoFEL) scale was revised, and its latent structure was explored through principal axis factoring in a nonclinical sample (n = 559). Dementia professionals subsequently reviewed the revised DoFEL for content validity, followed by confirmatory factor analysis in another nonclinical sample (n = 135). Additionally, 49 participants with mild cognitive impairment (MCI) and 33 healthy controls completed the DoFEL, Addenbrooke's Cognitive Examination-Revised (ACE-R) and a Visual Short-Term Memory Binding Task (VSTMBT). Correlation analysis and binomial regression were used to examine the relationship between DoFEL scores and cognitive measures and to assess its ability to differentiate between healthy controls and MCI patients. The revised DoFEL showed satisfactory structural and construct validity, although some items lacked content validity. Significant negative associations were found between DoFEL scores and ACE-R (r = -0.66, p < 0.001) as well as VSTMBT (r = -0.52, p=0.003) performances. Binomial regression demonstrated the DoFEL's effectiveness in distinguishing healthy controls from MCI patients (AUC = 0.95). These findings suggest that linking memory binding with functional performance could enhance functional assessment in early-stage AD.