Associations of plasma p-tau231 with serial position recall performance in free-of-dementia individuals.

Cognitive assessment and analysis of plasma biomarkers are lower-cost options for the early assessment of Alzheimer's disease (AD). In this study, we examined whether serial position markers in the Rey's AVLT were sensitive to plasma AD biomarkers in cognitively unimpaired older individuals. Participants (n = 327; mean age = 70.4, SD = 10.4) were free of dementia (MMSE = 24+) at baseline and recruited as part of the Memory Evaluation Research Initiative (MERI; Nathan Kline Institute, NY, USA). Data included plasma p-tau231, Aβ40 and Aβ42, AVLT scores and demographics. Bayesian linear and logistic regression analyses were carried out with plasma biomarkers as outcomes (including the Aβ42/40 ratio); memory scores, including traditional metrics and serial position scores, were predictors; and age, years of education, APOE ε4-status and reported gender were control variables. Results indicated that plasma p-tau231 was associated primarily with delayed primacy recall (first four words): the more primacy words were recalled, the lower the plasma p-tau231 levels were. This study confirms that serial position analysis of word-list recall data, and particularly delayed primacy, is a valuable tool for the identification of in vivo AD-related pathology in cognitively unimpaired individuals.