The recency ratio is related to CSF amyloid beta 1-42 levels in MCI-AD

Objective As anti-amyloid therapeutic interventions shift from enrolling patients with Alzheimer's disease (AD) dementia to individuals with pre-clinical disease, the need for sensitive measures that allow for non-invasive, fast, disseminable, and cost-effective identification of preclinical status increases in importance. The recency ratio (Rr) is a memory measure that relies on analysis of serial position performance, which has been found to predict cognitive decline and conversion to early mild cognitive impairment (MCI). The aim of this study was to test Rr's sensitivity to cerebrospinal fluid (CSF) levels of the core AD biomarkers in individuals with MCI-AD and controls. Methods Baseline data from 126 (110 controls and 16 MCI-AD) participants from the Wisconsin Alzheimer's Disease Research Center were analysed. Partial correlations adjusting for demographics were carried out between CSF measure of amyloid beta (A beta 40, A beta 42, and the 40/42 ratio) and tau (total and phosphorylated), and memory measures (Rr, delayed recall, and total recall) derived from the Rey's Auditory Verbal Learning Test. Results Results indicated that Rr was the most sensitive memory score to A beta 42 levels in MCI-AD, while no memory score correlated significantly with any biomarker in controls. Conclusions This study shows that Rr is a sensitive cognitive index of underlying amyloid beta pathology in MCI-AD.