Psycholinguistic properties of words on fluency testing relate to different aspects of subjective cognitive decline

Abstract

AbstractBackgroundSubjective Cognitive Decline (SCD) is posited as a marker of preclinical Alzheimer’s disease. However, the nature of SCD and its relationship with objective cognition remain the subject of debate. More sensitive markers of objective cognition are likely needed to capture variability in SCD; one candidate is the psycholinguistic information embedded in language tasks, such as lexical frequency and concreteness, which is rich in cognitive information. In addition, attention to the nature of SCD is important for advancing our understanding of its relationship with objective cognition. Here we investigate how psycholinguistic information (lexical frequency and concreteness) relate to different sets of items on an SCD scale.MethodParticipants included 74 cognitively healthy older adults (mean age = 73.76 (7.20), education =16.91 (2.20), 66% female, 85% Caucasian, 10% African American, 4% Asian and 1% other). SCD was measured with a 20‐item questionnaire, using a 7‐point Likert scale to rate difficulty on each item compared with others their age. Principal Component Analysis (PCA) was conducted to derive underlying SCD factors. Participants also completed semantic fluency (animals) and phonemic fluency (CFL) tasks. Lexical frequency values were computed for each word generated on fluency tasks. Concreteness was computed for CFL only; this value would not vary within a semantic task. Nonparametric partial correlations between psycholinguistic measures and SCD factors were conducted, controlling for age, sex and education.ResultsPCA identified three SCD factors with Eigen values >1 that together explained 63% of the total variance. Factor 1 loaded primarily on memory, Factor 2 was a combination of memory and language, and Factor 3 related to attention/executive function. Lexical frequency (animals) was correlated with Factor 1 only; higher SCD related to higher frequency (more common) animals (r=.27, p=.025). Concreteness (CFL) was correlated with Factor 2 only; higher SCD was associated with more concrete, less abstract, words (r=.25, p=.035).ConclusionTwo measures of psycholinguistic information were uniquely related to different SCD items. This double dissociation reinforces the idea that mapping SCD to objective cognition requires a carefully refined measurement approach with regard to subjective experiences and the information collected from objective measures.