Plasma proteomic associations with Alzheimer's disease endophenotypes.

Clinical Alzheimer's disease is currently characterized by cerebral β-amyloidosis associated with cognitive impairment. However, most cases of Alzheimer's disease are associated with multiple neuropathologies at autopsy. The peripheral protein changes associated with these disease endophenotypes are poorly understood. In this study, we analyzed the plasma proteomes of individuals from four cohorts (n = 2,139 participants) to identify proteins and pathways associated with cerebral β-amyloidosis and other neuropathologies, including tau, Lewy bodies, TDP43, cerebral amyloid angiopathy, atherosclerosis, arteriolosclerosis and infarcts as well as cognitive function. Analyses in a cohort with paired brain data showed that known neuropathologies could account for only half of proteins associated with cognitive function and that many plasma proteins associated with these neuropathologies are not strongly correlated to levels in brain, suggesting a potential contribution of peripheral factors to the development of Alzheimer's disease endophenotypes. Targeting pathways represented by these peripheral proteins may modify Alzheimer's disease risk or disease progression.