The nerve tissue in the brain of Alzheimer's patients have 'plaques' and 'tangles' that cause problems in brain function. A gene for epsilon apolipoprotein (Apo E) appears to influence the development of Alzheimer's. Apo E is one of the proteins that accumulate in nerve plaques in Alzheimer's. Between 50% and 80% of person's with the gene develop Alzheimer's, indicating that the cause of the disease is multifactorial and involves environmental factors.
Beta amyloid, the main component of neuritic plaques, is a source of free radicals. This oxidative stress causes increased production of prostaglandins and, in the case of Alzheimer's, excess glutamate that, in turn, destroys neurons. Accumulation of beta amyloid in the brain's blood vessels affects blood supply to the brain.
Other factors that can cause damage to either brain tissue or the blood supply to the brain, include infections, heavy metals (aluminum, mercury, zinc, copper, and iron), electromagnetic fields, hormonal and nutritional deficiencies.