Measuring longitudinal cognition: Individual tests versus composites

Erin M Jonaitis; Rebecca L Koscik; Lindsay R Clark; Yue Ma; Tobey J Betthauser; Sara E Berman; Samantha L Allison; Kimberly D Mueller; Bruce P Hermann; Carol A Van Hulle; Bradley T Christian; Barbara B Bendlin; Kaj Blennow; Henrik Zetterberg; Cynthia M Carlsson; Sanjay Asthana; Sterling C Johnson

doi:10.1016/j.dadm.2018.11.006

Measuring longitudinal cognition: Individual tests versus composites

Alzheimers Dement (Amst). 2019 Jan 11:11:74-84. doi: 10.1016/j.dadm.2018.11.006. eCollection 2019 Dec.

Authors

Erin M Jonaitis¹, Rebecca L Koscik¹, Lindsay R Clark^{1

2

3}, Yue Ma³, Tobey J Betthauser³, Sara E Berman³, Samantha L Allison^{2

3}, Kimberly D Mueller^{1

3

4}, Bruce P Hermann⁵, Carol A Van Hulle³, Bradley T Christian^{6

7}, Barbara B Bendlin³, Kaj Blennow^{8

9}, Henrik Zetterberg^{8

9

10

11}, Cynthia M Carlsson^{2

1

3}, Sanjay Asthana^{2

3}, Sterling C Johnson^{2

1

3}

Affiliations

¹ Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
² Geriatric Research Education and Clinical Center, William S. Middleton Memorial Veterans Hospital, Madison WI, USA.
³ Wisconsin Alzheimer's Disease Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA.
⁴ Department of Communication Sciences and Disorders, University of Wisconsin, Madison, WI, USA.
⁵ Department of Neurology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
⁶ Department of Medical Physics, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA.
⁷ Department of Psychiatry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA.
⁸ Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden.
⁹ Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden.
¹⁰ Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, UK.
¹¹ UK Dementia Research Institute at UCL, London, UK.

Abstract

Introduction: Longitudinal cohort studies of cognitive aging must confront several sources of within-person variability in scores. In this article, we compare several neuropsychological measures in terms of longitudinal error variance and relationships with biomarker-assessed brain amyloidosis (Aβ).

Methods: Analyses used data from the Wisconsin Registry for Alzheimer's Prevention. We quantified within-person longitudinal variability and age-related trajectories for several global and domain-specific composites and their constituent scores. For a subset with cerebrospinal fluid or amyloid positron emission tomography measures, we examined how Aβ modified cognitive trajectories.

Results: Global and theoretically derived composites exhibited lower intraindividual variability and stronger age × Aβ interactions than did empirically derived composites or raw scores from single tests. For example, the theoretical executive function outperformed other executive function scores on both metrics.

Discussion: These results reinforce the need for careful selection of cognitive outcomes in study design, and support the emerging consensus favoring composites over single-test measures.

Keywords: Biostatistics; Cognitive aging; Composite scores; Intraindividual variability; Longitudinal data analysis; Neuropsychological tests.

Abstract

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