Other factors also play a role. A mutated form of a protein known as tau is found in these tangles. Some experts believe that this defective version blocks the activity of normal tau proteins, which help in the assembly of a healthy microtubule structure. These plaques are found outside the nerve cells surrounded by the debris of dying neurons. High levels of beta amyloid are associated with reduced levels of the neurotransmitter acetylcholine .
Neurotransmitters are chemical messengers in the brain.
Acetylcholine is part of the cholinergic system, which is essential for memory and learning, and which is progressively destroyed in Alzheimer's patients. If the channels that carry ions are damaged, an imbalance can interfere with nerve function and signal transmission. ERAB appears to combine with beta amyloid, which in turn attracts new beta amyloid from outside the cells. High amounts of ERAB also may also enhance the nerve-destructive power of this protein partner. AMY plaques resemble beta amyloid so closely that only with the use of highly sophisticated techniques were researchers able to detect them.