Association of β-Amyloid Level, Clinical Progression, and Longitudinal Cognitive Change in Normal Older Individuals
Laura M. van der Kall, Thanh Huong Truong, Samantha C. Burnham, Vincent Doré, Rachel S. Mulligan, Svetlana Bozinovski, Fiona Lamb, Pierrick Bourgeat, Jürgen Fripp, Stephanie A. Schultz, Yen Ying Lim, Simon M. Laws, David Ames, Christopher Fowler, Stephanie R. Rainey‐Smith, Ralph N. Martins, Olivier Salvado, Joanne Robertson, Paul Maruff, Colin L. Masters, Victor L. Villemagne, Christopher C. Rowe
Abstract
OBJECTIVE: To determine the effect of β-amyloid (Aβ) level on progression risk to mild cognitive impairment (MCI) or dementia and longitudinal cognitive change in cognitively normal (CN) older individuals. METHODS: All CN from the Australian Imaging Biomarkers and Lifestyle study with Aβ PET and ≥3 years follow-up were included (n = 534; age 72 ± 6 years; 27% Aβ positive; follow-up 5.3 ± 1.7 years). Aβ level was divided using the standardized 0-100 Centiloid scale: <15 CL negative, 15-25 CL uncertain, 26-50 CL moderate, 51-100 CL high, >100 CL very high, noting >25 CL approximates a positive scan. Cox proportional hazards analysis and linear mixed effect models were used to assess risk of progression and cognitive decline. RESULTS: < 0.001). CONCLUSION: The risk of MCI or dementia over 5 years in older CN is related to Aβ level on PET, 5% if negative vs 25% if positive but ranging from 12% if 26-50 CL to 28% if 51-100 CL and 50% if >100 CL. This information may be useful for dementia risk counseling and aid design of preclinical AD trials.