Amyloid Positivity in the Alzheimer/Subcortical-Vascular Spectrum

Abstract

Objective We investigated the frequency of beta-amyloid (A beta) positivity in 9 groups classified according to a combination of 3 different cognition states and 3 distinct levels of white matter hyperintensities (WMH) (minimal, moderate, and severe) and aimed to determine which factors were associated with A beta after controlling for WMH and vice versa. Methods A total of 1,047 individuals with subjective cognitive decline (SCD, n = 294), mild cognitive impairment (MCI, n = 237), or dementia (n = 516) who underwent A beta PET scans were recruited from the memory clinic at Samsung Medical Center in Seoul, Korea. We investigated the following: (1) A beta positivity in the 9 groups, (2) the relationship between A beta positivity and WMH severity, and (3) clinical and genetic factors independently associated with A beta or WMH. Results A beta positivity increased as the severity of cognitive impairment increased (SCD [15.7%], MCI [43.5%], and dementia [76.2%]), whereas it decreased as the severity of WMH increased (minimal [54.5%], moderate [53.9%], and severe [41.0%]) or the number of lacunes (0 [59.0%], 1-3 [42.0%], and >3 [23.4%]) increased. A beta positivity was associated with higher education, absence of diabetes, and presence of APOE epsilon 4 after controlling for cognitive and WMH status. Conclusion Our analysis of A beta positivity involving a large sample classified according to the stratified cognitive states and WMH severity indicates that Alzheimer and cerebral small vessel diseases lie on a continuum. Our results offer clinicians insightful information about the association among A beta, WMH, and cognition.