Associations between the logical memory test story recall metrics and plasma biomarkers for Alzheimer's disease in individuals free of dementia.

Abstract

Objective: Blood-based biomarkers are valued for their lower cost and less invasive nature, though issues with widespread implementation and accessibility remain. Process-based scores from story recall have been shown to detect neuronal network disturbances typical of Alzheimer's disease (AD) pathology more effectively than traditional metrics. This study examined the associations between process-based scores and concurrent plasma AD biomarkers in older adults without dementia, while also comparing them to traditional metrics. Additionally, it also investigated the diagnostic utility of these metrics in detecting plasma p-tau217 positivity. Methods: Data from 416 participants (mean age = 66.6 ± 7) free of dementia were extracted from the Wisconsin Registry for Alzheimer's Prevention (WRAP). Logical Memory Test (LMT) and plasma p-tau217, p-tau181, p-tau231, Aβ42/Aβ40 ratio, GFAP and NfL levels were analyzed. Bayesian regression models assessed associations between plasma biomarkers and both process-based and traditional LMT scores, controlling for the covariates. Results: The best-fitting model for plasma p-tau217 included Total ratio (Tr) and Immediate recall (BF10=573), but Tr showed stronger evidence of association (mean coefficient = 0.208; BFinclusion=14.4) than Immediate recall (mean coefficient=-0.007; BFinclusion=1.7). Tr was also the best predictor of plasma p-tau181 (mean coefficient = 0.144; BF10=10.5) and GFAP (mean coefficient = 0.141; BF10=5.8), outperforming traditional LMT scores. No memory scores were associated with plasma p-tau231 or Aβ42/40 ratio levels. Tr score was the strongest single predictor of p-tau217 positivity (BF₁₀=38). Conclusions: These findings suggest that process-based memory scores might be useful in enhancing the detection of neuronal network disturbances associated with AD pathology, especially in settings where biomarker testing is unavailable.