A composite measure of cognitive and functional progression in Alzheimer's disease: Design of the Capturing Changes in Cognition study

Roos J Jutten; John Harrison; Frank Jan de Jong; André Aleman; Craig W Ritchie; Philip Scheltens; Sietske A M Sikkes

doi:10.1016/j.trci.2017.01.004

A composite measure of cognitive and functional progression in Alzheimer's disease: Design of the Capturing Changes in Cognition study

Alzheimers Dement (N Y). 2017 Feb 9;3(1):130-138. doi: 10.1016/j.trci.2017.01.004. eCollection 2017 Jan.

Authors

Roos J Jutten¹, John Harrison^{1

2}, Frank Jan de Jong³, André Aleman⁴, Craig W Ritchie⁵, Philip Scheltens¹, Sietske A M Sikkes^{1

6}

Affiliations

¹ Alzheimer Center, Department of Neurology, VU University Medical Center, Amsterdam Neuroscience, Amsterdam, The Netherlands.
² Metis Cognition Ltd, Kilmington Common, Warminster, United Kingdom.
³ Department of Neurology, Erasmus Medical Center, Rotterdam, The Netherlands.
⁴ Department of Neurosciences, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
⁵ Centre for Dementia Prevention, University of Edinburgh, Edinburgh, United Kingdom.
⁶ Department of Epidemiology & Biostatistics, VU University Medical Center, Amsterdam, The Netherlands.

Abstract

Introduction: Cognitive testing in Alzheimer's disease (AD) is essential for establishing diagnosis, monitoring progression, and evaluating treatments. Assessments should ideally be brief, reliable, valid, and reflect clinically meaningful changes. There is a lack of instruments that meet all these criteria. In the Capturing Changes in Cognition (Catch-Cog) study, we seek to correct these deficiencies through the development and validation of a composite measure combining cognition and function: the cognitive-functional composite (CFC). We expect that the CFC is able to detect clinically relevant changes over time in early dementia stages of AD.

Methods/design: We will include patients (n = 350) with mild cognitive impairment or mild dementia due to AD from memory clinics in the Netherlands and the United Kingdom. We will include cognitively healthy volunteers (n = 30) as a control group. The CFC is based on the "cognitive composite" and the Amsterdam instrumental activities of daily living questionnaire. We will investigate test-retest reliability with baseline and 2- to 3-week follow-up assessments (n = 50 patients and n = 30 healthy controls). We will involve experts and participants to evaluate the initial feasibility and refine the CFC if needed. Subsequently, we will perform a longitudinal construct validation study in a prospective cohort (n = 300) with baseline, 3-, 6-, and 12-month follow-up assessments. The main outcome is cognitive and functional progression measured by the CFC. Reference measures for progression include traditional cognitive and functional tests, disease burden measures, and brain imaging methods. Using linear mixed modeling, we will investigate longitudinal changes on the CFC and relate these to the reference measures. Using linear regression analyses, we will evaluate the influence of possible confounders such as age, gender, and education on the CFC.

Discussion: By performing an independent longitudinal construct validation, the Catch-Cog study of the novel CFC will contribute to the improvement of disease monitoring and treatment evaluation in early dementia stages of AD.

Keywords: Alzheimer's disease; Cognition; Composite measure; Daily function; Longitudinal construct validation; Mild cognitive impairment; Prospective cohort.