Semantic network function captured by word frequency in nondemented APOE ε4 carriers.

Abstract

Objective: Accurate identification of the earliest cognitive changes associated with Alzheimer's disease (AD) is critically needed. Item-level information within tests of category fluency, such as lexical frequency, harbors valuable information about the integrity of semantic networks affected early in AD.To determine the potential of lexical frequency as a cognitive marker of AD risk, we investigated whether lexical frequency of animal fluency output differentiated APOE ε4 carriers from noncarriers in a cross-sectional design among older African-American adults without dementia. Method: We analyzed animal fluency performance using mean number of items and mean lexical frequency among 230 cognitively normal African Americans with and without the APOE ε4 allele. Results: Lexical frequency was higher in APOE ε4 carriers than noncarriers when analyzed as a mean score and within time bins. In contrast, we found no group difference in the number of items produced. Lexical frequency was particularly sensitive to ε4 status after the first 10 s of the 60-s animal fluency task. Conclusion: Our results suggest that psycholinguistic features may hold value as a cognitive biomarker for identifying people at high risk of AD. General Scientific SummaryDecline in cognition occurs years before the symptoms are distinct enough to establish a clinical diagnosis of Alzheimer's disease (AD) based on traditional neuropsychological test scores. We showed that an alternative, psycholinguistic score of the category fluency task could predict AD genetic risk (having the APOE ε4 allele) in older adults whose overall cognition and function are within normal limits. These results suggest that psycholinguistic features may hold value as a cognitive biomarker for identifying people at high risk of AD.

Semantic loss marks early Alzheimer's disease‐related neurodegeneration in older adults without dementia

“…A promising avenue to exploit semantic fluency performance is to analyze item‐level data. Classically, analyses of cluster and switches have already been shown to add above and beyond total number of items in detecting MCI 40,41 and very mild AD, 42 and usage of psycholinguistic variables has demonstrated its value in distinguishing cognitively normal individuals at increased genetic risk of AD dementia by virtue of carrying an APOE e4 allele 43 . More research in this area should be encouraged, as the present study adds more evidence to the growing body of research on semantic breakdown in the very early stages of AD.…”

Demographic Effects on Longitudinal Semantic Processing, Working Memory, and Cognitive Speed

“…Semantic memory efficiency, by contrast, allows for effective access to the storage of conceptual meanings, including the categories that concepts belong to. Semantic information is thought to be organized in a network, in which semantic activation spreads through related concepts (e.g., Vonk, Flores, et al, 2019 ). Thus, a task like Animal Fluency reflects the ability to quickly and accurately access concepts related to a category like animals .…”

“…To truly capture within-person trajectories of change over time, more follow-up measures are needed. Additionally, having only two measurement times prohibits consideration of practice effects that generally wear off after the second or third testing occasion ( Vonk, Arce Rentería, et al, 2019 ), which may bias estimates of change over time ( Vivot et al, 2016 ). Nonetheless, work by Mitrushina and Satz (1995) suggests that the ANT and BNT tasks may not be impacted by practice effects.…”

Cross-sectional associations of amyloid burden with semantic cognition in older adults without dementia: A systematic review and meta-analysis

“…Episodic memory is the most characteristic cognitive function impaired in early Alzheimer’s disease ( Bäckman et al, 2001 ; Hodges, 1998 ). Additionally, a large body of research has demonstrated the role of subtle semantic decline in early stages of the disease or in individuals at high risk for Alzheimer’s disease (e.g., Chertkow et al, 2008 ; Papp et al, 2016 ; Vonk et al, 2019a ). While a decline in episodic memory is not only present in Alzheimer’s disease but to a lesser extent also in normal aging, several aspects of semantic cognition stay relatively intact with normal aging ( Horn and Cattell, 1966 , 1967 ; Park et al, 2002 ; Salthouse, 2010 ; Vonk et al, 2020 ).…”