Plasma ?-amyloid in Alzheimer's disease and vascular disease.

ABSTRACT: Implementation of amyloid biomarkers in clinical practice would be accelerated if such biomarkers could be measured in blood. We analyzed plasma levels of A?42 and A?40 in a cohort of 719 individuals (the Swedish BioFINDER study), including patients with subjective cognitive decline (SCD), mild cognitive impairment (MCI), Alzheimer's disease (AD) dementia and cognitively healthy elderly, using a ultrasensitive immunoassay (Simoa platform). There were weak positive correlations between plasma and cerebrospinal fluid (CSF) levels for both A?42 and A?40, and negative correlations between plasma A?42 and neocortical amyloid deposition (measured with PET). Plasma levels of A?42 and A?40 were reduced in AD dementia compared with all other diagnostic groups. However, during the preclinical or prodromal AD stages (i.e. in amyloid positive controls, SCD and MCI) plasma concentration of A?42 was just moderately decreased whereas A?40 levels were unchanged. Higher plasma (but not CSF) levels of A? were associated with white matter lesions, cerebral microbleeds, hypertension, diabetes and ischemic heart disease. In summary, plasma A? is overtly decreased during the dementia stage of AD indicating that prominent changes in A? metabolism occur later in the periphery compared to the brain. Further, increased levels of A? in plasma are associated with vascular disease.

SUBMITTER: Janelidze S 

PROVIDER: S-EPMC4886210 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature