Measuring Change over Time on Cognitive Screening Measures: An Evaluation of the Psychometric Properties of ACE-III, CBI-R, and EMQ for the Purpose of Dementia Screening

Abstract

Introduction: Cognitive screening measures are an established part of a dementia assessment and often include measures of subjective difficulties, e.g., Everyday Memory Questionnaire (EMQ), informant-rated difficulty, Cambridge Behavioural Inventory – Revised (CBI-R), and objective cognitive assessments like Addenbrooke’s Cognitive Examination (ACE-III). While these measures have validity for the purpose of diagnosing dementia, in clinical practice they are often used outside of their evidence base for the purpose of cognitive re-assessment. The current study sought to evaluate the psychometric properties for the repeated use of these assessments. Methods: This study used a longitudinal design, which included 49 healthy controls, 33 people with subjective memory difficulties, and 10 people with Alzheimer’s disease (AD) being assessed twice, with approximately a 1-year interval between assessments. Results: The EMQ has adequate re-test reliability (r = 0.78), but people with an AD diagnosis rated their memory as better than those with SMD, making it unsuitable as a measure. The CBI-R had moderate re-test reliability (r = 0.62). However, deterioration on the CBI-R was not useful for diagnosing AD. The ACE-III has high re-test reliability (r = 0.89). A change of five was associated with reasonable classification accuracy for identifying AD and achieved statistical significance. Conclusion: Using a 1-year interval, of the three measures used in this study, only the ACE-III total score may be a useful measure of change over time, although it should be applied cautiously due to the lack of representativeness of the sample, and change scores should always be triangulated with other forms of evidence of deterioration.