In Reply: Dr Okereke and colleagues point out differences in the results of our study and those from the Nurses' Health Study1 in regards to the association between education and plasma β-amyloid 42/40 level. Several key elements of the studies likely account for these differences. First, we found an interaction with β-amyloid 42/40 level, education, and cognitive decline, while the Nurses' Health Study did not report such an interaction. Second, the Nurses' Health Study had a more homogenous population that consisted primarily of white women who were all highly educated.1 Conversely, our sample from the Health ABC study comprised approximately 50% male and 50% black elderly individuals. We agree that it would be useful to pool studies to determine how the association between β-amyloid 42/40 level and cognitive function is modified by education in a larger sample including diverse racial and ethnic groups and a wide range of educational attainment. This will be a useful next step in fully understanding β-amyloid 42/40 as a potential biomarker for Alzheimer disease and other dementias.
Yaffe K, Weston A. Plasma β-Amyloid Level, Cognitive Reserve, and Cognitive Decline—Reply. JAMA. 2011;305(16):1655–1656. doi:10.1001/jama.2011.526