Greater Amyloid Burden in Cognitive Networks in Preclinical Alzheimer's Disease

BackgroundIn preclinical Alzheimers disease (pAD), regional patterns of amyloid-{beta} (A{beta}) deposition are well characterized but it is unclear how this process varies across functional networks. ObjectiveDetermine how A{beta} accumulation in functional networks ("network-amyloid burden" [NAB]) varies by age, network type (cognitive vs. non-cognitive), and A{beta} status (A{beta}+/A{beta}-), and relates to cognition. Methods157 cognitively unimpaired adults (45-84 years; n=28 A{beta}+ per neuroradiological read) underwent brain MRI, amyloid PET (18F-florbetapir), and neuropsychological testing. NAB was calculated as the mean standard uptake value ratio within 7 networks categorized as cognitive (fronto-parietal, default mode, ventral and dorsal attention, limbic) or non-cognitive (somato-motor, visual). Linear mixed models tested how NAB varies across age, networks (by type and each separately), A{beta} status, and their interactions, and relationships between NAB and cognition. ResultsNAB increased with age, most prominently in fronto-parietal and default mode networks. NAB was higher in cognitive than non-cognitive networks, and this difference was more pronounced in A{beta}+ individuals. NAB was not significantly associated with cognition. ConclusionsCognitive brain networks are more vulnerable to amyloid accumulation with aging and in pAD than non-cognitive networks. Cognitive NAB may be useful for early detection and as a target for intervention in pAD.