Toward optimizing measurement of self‐perceived cognitive function ‐ a global expert survey on behalf of the SCD‐I Working Group

Abstract

AbstractBackgroundAssessment of self‐perceived cognitive decline (SCD) is relevant in the context of Alzheimer’s disease and related disorders, but heterogeneity in measurement limits its interpretability and usability. Selection of optimal content for a questionnaire measuring SCD requires statistical information and expert opinion to ensure reliability as well as acceptability and feasibility. This study aims to survey experts about their perspectives on essential features of SCD measurement.MethodThe survey was distributed through the ISTAART Subjective Cognitive Decline PIA, International Neuropsychological Society’s Dementia Special Interest Group, and authors’ professional networks. Targeted experts included professionals working with older adults with SCD through research and/or clinical practice. Main topics were item content, item format, and questionnaire features. Topics were evaluated with multiple choice questions and open‐ended questions. Furthermore, experts were shown items from existing SCD questionnaires with relatively high information value as identified in a previous statistical harmonization effort using Item Response Theory analyses (see Rabin et al., 2021), and asked to select items they viewed as most relevant. Frequency analyses were performed.ResultNinety‐one experts (66% female) across four continents completed the questionnaire (Table 1). Thirty‐nine experts (43%) indicated routinely using an instrument to assess SCD (17 different instruments were mentioned). Seventy‐nine experts (87%) perceived a need for a harmonized SCD instrument. Whereas most experts (72%) responded that a questionnaire should measure both current ability and change in ability, views on the most relevant timeframe varied substantially (top choices: past year (33%) and past six months (25%)). Figure 1a and 1b show that items with the highest statistical information value were not necessarily selected as most relevant by experts. Preferred practical features of a questionnaire were availability of an informant version and coverage of multiple cognitive domains (chosen by 13% and 14% respectively). Preferred validation approaches were distinguishing psychiatric illness from neurodegenerative disorders and the correlation with neuropsychological test performance (both chosen by 20%).ConclusionDespite agreeing on the need for a harmonized SCD instrument, experts express varying views on optimal content, format, and validation approaches. The complementary information derived from statistical results and expert opinion can facilitate more comprehensive measurement of SCD.