A Neuropsychological Perspective on Defining Cognitive Impairment in the Clinical Study of Alzheimer’s Disease: Towards a More Continuous Approach

Abstract

The global fight against Alzheimer’s disease (AD) poses unique challenges for the field of neuropsychology. Along with the increased focus on early detection of AD pathophysiology, characterizing the earliest clinical stage of the disease has become a priority. We believe this is an important time for neuropsychology to consider how our approach to the characterization of cognitive impairment can be improved to detect subtle cognitive changes during early-stage AD. The present article aims to provide a critical examination of how we define and measure cognitive status in the context of aging and AD. First, we discuss pitfalls of current methods for defining cognitive impairment within the context of research shifting to earlier (pre)symptomatic disease stages. Next, we introduce a shift towards a more continuous approach for identifying early markers of cognitive decline and characterizing progression and discuss how this may be facilitated by novel assessment approaches. Finally, we summarize potential implications and challenges of characterizing cognitive status using a continuous approach.

Misinterpreting cognitive change over multiple timepoints: When practice effects meet age-related decline.

“…As the field of clinical neuropsychology evaluates the current state of normative data (Byrd & Rivera-Mindt, 2022), and while there is a strong push for repeated assessments, particularly via computerized testing (Jutten et al, 2022; Stricker et al, 2020), the results of the present study strongly suggest that the field would benefit from normative data for PEs over multiple retest visits. In particular, it may be beneficial to develop predicted PEs for specific tests in a diverse range of individuals retested at clinically relevant intervals across multiple retest visits (e.g., every 6 or 12 months).…”

The ambivalence toward neuropsychology in dementia research, diagnosis, and drug development: Myths and misconceptions

“…While clinical neuropsychologists tend to rely on established clinical tests they should also lead the way in facilitating biomarker research through development of novel sensitive and more flexible measures, 49 better and more inclusive normative data, 49 as well as improved methods of interpreting conventional tests 50 . Underserved populations also need better access to cognitive assessment.…”

“…The gold standard against which to evaluate the clinical utility of biomarkers has to include the appropriate cognitive markers, 17 with cognitive progression markers based on serial assessment being ideal. 49 Biomarker experts increasingly need to join forces with experts in cognition to map the possible interplay between cognition and various biomarkers as well as defining subtypes of dementias. Clinical health" (p. 7).…”

Characterizing Cognition in Everyday Life of Older Adults With Subjective Cognitive Decline

“…Data obtained from a control group would have been preferable. Third, our inclusion criteria used a dichotomous (y/n) approach to determine the presence of subjective experience of cognitive decline but a continuous approach (e.g., Likert-type scale) would have been more sensitive, has been suggested in recent literature (Jutten et al, 2022). Finally, because of the subjective nature of SCD, the role of memory self-efficacy should have been considered.…”