Semantic item-level metrics relate to future memory decline beyond existing cognitive tests in older adults without dementia

Abstract

In normal aging, the cognitive domain of semantic memory remains preserved, while the domain of episodic memory declines to some extent. In Alzheimer’s disease dementia, both semantic and episodic memory become impaired early in the disease process. Given the need to develop sensitive and accessible cognitive markers for early detection of dementia, we investigated among older adults without dementia whether itemlevel metrics of semantic fluency related to episodic memory decline above and beyond existing neuropsychological measures and total fluency score. Participants were drawn from the communitybased Washington Heights–Inwood Columbia Aging Project cohort (N = 583 English speakers,M age = 76.3 ± 6.8) followed up to five visits across up to 11 years. We examined the association of semantic fluency metrics with subsequent declines in memory performance using latent growth curve models covaried for age and recruitment wave. Results showed that item-level metrics (e.g., lexical frequency, age of acquisition, and semantic neighborhood density) were associated with a decline in episodic memory— even when covarying for other cognitive tests—while the standard total score was not. Moderation analyses showed that the relationship of semantic fluency metrics with memory decline did not differ across race, sex/gender, or education. In conclusion, item-level data hold a wealth of information with potential to reveal subtle semantic memory impairment, which tracks with episodic memory impairment, among older adults without dementia beyond existing neuropsychological measures. Implementation of psycholinguistic metrics may point to cognitive tools that have better prognostic value or are more sensitive to cognitive change in the context of clinical trials or observational studies.