The pathophysiology of AD is very complex. Aβ plaques, and
NFTs are the main neuropathological hallmarks. Senile Aβ
plaques are important pathophysiological changes seen in
AD and thus form the essential component of the “amyloid
hypothesis. This hypothesis proposes that the deposition of Aβ
plaques precedes and induces the neuronal abnormalities that
underlie the development of dementia.[4] In AD, the soluble form
of Aβ has toxic effects on the neurons, including increasing the
oxidative stress, precipitating the programmed cell death and
lowering the cell injury threshold.[5] NFTs are dense intracellular
protein deposits that are composed of the normal cytoskeletal
protein, tau. The formation of NFTs in neurons is associated with
extensive phosphorylation and cross‑linking of the tau molecules.
However, the initiating event is not well understood.[6] Many of
the therapeutic strategies in AD, including neuro‑restorative
strategies to be discussed below, depend on treating the
above mentioned mechanisms, especially decreasing the Aβ
deposits. However, the pathophysiology of AD involves multiple
mechanisms, that are at present, not well understood.