Does feature binding account for functional decline in patients with mild cognitive impairment? Evidence from the Details of Function of Everyday Life Questionnaire (DoFEL)

Abstract

AbstractBackgroundAvailable functional scales used to discriminate normal and abnormal ageing are informative of basic abilities (e.g., bathing, grooming, feeding, etc.). These are complex functions and the tools used to assess them lack theories from cognitive ageing. These features have rendered them insensitivity to the early stages of dementia such as that caused by Alzheimer’s disease (AD). To overcome these limitations, we need to improve our understanding of the cognitive underpinnings of functional decline. The ability to bind information in memory (i.e., feature binding) declines from the preclinical stages of AD. It remains unknown whether such subtle cognitive deficits can underpin decline of instrumental activities of everyday life (IADL, e.g., managing finances, using technologies, shopping) found in the prodromal stages of AD. To address this need we have developed a theory‐driven scale namely Details of Function of Everyday Life Questionnaire (DoFEL). We used DoFEL to investigate if cognitive constructs such as memory binding can account for impairment of specific abilities that support instrumental functions.MethodsParticipants (N=168) completed a neuropsychological test battery, comprising of a set of novel and traditional neuropsychological tasks known to be useful in the early detection of AD. Binomial logistic regression was utilised to evaluate the predictive effect of DoFEL relative to other scales such as the Addenbrooke's cognitive examination (ACE).ResultsA stratified model incorporating the Shopping and Money, Work and Social Life and Domestic Chores domains of the DoFEL, X2(3)=48.57, p < 0.001, R2 = 0.70, AUC=0.94, demonstrated comparable accuracy to that of the ACE‐R scores, X2(1)=47.61, p < 0.001, R2 = 0.71, AUC=0.94. The DoFEL scores informing on conjunctive binding abilities had a moderately high accuracy and Nagelkerke's R2 results, indicating a higher predictive power to discriminate between healthy older adults and individuals with MCI.ConclusionsFunctional composite measures integrating feature binding constructs within measures of IADL impairment are plausible future indicators of early cognitive decline in prodromal AD. Further research is required to evaluate the validity of DoFEL and its sensitivity across the whole AD continuum.