Blood amyloid levels and risk of dementia in the Ginkgo Evaluation of Memory Study (GEMS): A longitudinal analysis

Introduction: Both high or low plasma amyloid levels have been associated with risk of dementia in nondemented subjects. Methods: We examined baseline plasma beta-amyloid (A beta) levels in relationship to incident dementia during a period of 8.5 years in 2840 subjects age >75 years; 2381 were cognitively normal (CN) and 450 mild cognitive impairment. Results: Increased plasma A beta 1-40 and A beta 1-42 levels were associated with gender (women), age, low education, creatinine levels, history of stroke, and hypertension. CN participants who developed dementia had lower levels of A beta 1-42 and A beta 1-42/A beta 1-40 ratio compared with those who did not. A beta levels did not predict dementia in mild cognitive impairment participants. Discussion: There was an inverse association between A beta 1-42 and A beta 1-42/A beta 1-40 ratio to risk of dementia in CN participants. Cerebral and cardiovascular disease and renal function are important determinants of increased A beta levels and must be considered in evaluations of relationship of plasma A beta and subsequent risk of dementia. (C) 2019 Published by Elsevier Inc. on behalf of the Alzheimer's Association.