Category - Diet & Lifestyle

1 - Inflammation (from infection, diet or other causes)

2 - Decline and shortage of supportive nutrients, hormones and other brain-supporting molecules

3 - Toxic substances such as metals or biotoxins (poisons produced by microbes such as molds)

The protective response causes APP (Amyloid Precursor Protein, the long molecule that protrudes from neurons) to be cut into four fragments, including amyloid-beta, that downsize the neural network and eventually destroy synapses and neurons. When the APP molecule is cut into those four pieces, it is not cut into the two pieces that nourish and maintain synapses.

Alzheimer's disease is a state of the brain in which there is an imbalance between the reorganization of synapses that have outlived their usefulness (and which the brain can stand to lose - healthy destruction) and the maintenance or creation of existing and new synapses (which the brain needs to sustain old memories and form new ones, as well as perform other cognitive functions). That imbalance  comes from too many  of the synapse- and neuron-destroying quartet  of molecules snipped from APP and too few  of the synapse- and neuron-sustaining duo  of molecules snipped from APP.