Disease - linked mutations in these genes result in increased
production of the 42 - amino - acid form
of the peptide (Abeta42), which is the predominant form found in the
amyloid plaques of Alzheimer's disease.
These include insoluble extracellular
plaques made
of beta -
amyloid peptide (Aβ); intracellular neurofibrillary tangles (NFTs) resulting from the hyperphosphorylation
of tau (a microtubule - associated protein); loss
of hippocampal neurons; a decrease in
production of brain acetylcholine; and a marked decline in glucose usage in regions
of the brain associated with memory and learning.5,11,20 - 22 All
of these changes can be logically explained as the sequelae resulting from long - term dysregulation
of insulin signaling and glucose metabolism.