{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Amyloid beta (Aβ or Abeta) consists of peptides of 36–43 amino acids that are crucially involved in Alzheimer’s disease as the main component of the amyloid plaques found in the brains of Alzheimer patients. The plaques are composed of a tangle of regularly ordered fibrillar aggregates called amyloid fibers, a protein fold shared by other peptides such as the prions associated with protein misfolding diseases. Amyloid beta circulates in plasma, cerebrospinal fluid (CSF) and brain interstitial fluid (ISF) mainly as soluble Aβ40. Amyloid beta is the main constituent of brain parenchyma and vascular amyloid; it contributes to cerebrovascular lesions and is neurotoxic."}]}]}