Functional Cognition in Older Adults with Mild Cognitive Impairment and Mild Dementia: Validation of the Large Allen's Cognitive Level Screen

Abstract

Assessment of everyday function is essential to diagnose dementia and distinguish Mild Cognitive Impairment (MCI) from dementia. The term ‘functional cognition’ links the two constructs of function and cognition, integrating the literature. It is defined as “the observable performance of everyday activities resulting from a dynamic interaction between motor abilities, activity demands and the task environment, which is guided by cognitive abilities” (Wesson et al. 2016). This thesis examines functional cognition and its assessment in older adults with MCI or mild dementia living in the community. A systematic review of performance-based measures was completed: no consensus in assessment of either functional cognition or complex everyday activities exists, and a “gold standard” is lacking. Psychometric properties are inadequate, and based on these alone, no single instrument can be recommended. Considering the influence of clinical utility on instrument choice, the Large Allen’s Cognitive Level Screen version 5 (LACLS-5) was cautiously recommended, and cross-sectional and longitudinal studies examining its construct validity and responsiveness were conducted. Findings support the validity of the LACLS-5 as a performance-based measure of functional cognition, and its use with older adults with mild dementia. The LACLS-5 did not reliably distinguish MCI from normal cognition, suggesting it is less able to detect subtle impairment, and change in LACLS-5 scores over 12 months was minimal, suggesting low responsiveness. Responsiveness patterns differed between MCI and dementia, and according to type of responsiveness evaluated. Recommendations to strengthen psychometric properties of the LACLS-5 are made, and the need for further examination of change in functional cognition and evaluation instruments is highlighted. Research directions are provided to improve understanding of functional cognition and complex everyday activities in older adults with MCI or mild dementia