Multiple studies have identified two conditions — amyloid plaques and neurofibrillary tangles — as definitive proof of Alzheimer's disease. Alzheimer’s and amyloid plaques are therefore directly connected. Amyloids consist of protein fragments normally produced in the body. Healthy individuals eliminate these fragments. In patients with Alzheimer's and amyloid plaques associated with this disease, the amyloid fragments accumulate around the neurons in the brain and eventually harden and form indissoluble plaques.
A buildup of a particular protein fragment, beta amyloid, occurs in the brains of patients with Alzheimer's. Another type, tau protein, exists in the tangles that form within the cellular structure of brain neurons in Alzheimer’s. Researchers believe that the formation of these two elements causes the neurons in the brain to degrade, which in turn leads to the symptoms related to Alzheimer's and amyloid plaques. As the process continues, the cholinergic neurons in the brain that govern the transmission of nerve impulses, including memory, decrease. Some research suggests a connection with abnormal lipid metabolism and related cellular oxidation damage.
Apolipoprotein E (apoE), a specialized type of lipoprotein, has a major role in the brain. It enhances the transportation and elimination of lipids and beta amyloid. Some studies suggest that the presence of the apoE4 sub-type in the brain leads to less protection from changes in function that might occur with aging. Some of these studies indicate that the damage from this process can be lessened by dietary changes and risk modification. One of the most important factors is controlling cardiovascular risk factors including hyperlipedemia — excessively high total cholesterol — and low-density lipoprotein.
From all accounts, compelling evidence exists about the relationship between Alzheimer’s and amyloid plaques. The importance of early diagnosis of Alzheimer’s has led to research on how to identify these plaques as soon as possible. Originally, the only way to confirm their presence and a positive diagnosis of the disease came through an autopsy.