In the study conducted by Dr. Tanzi, he found out the biological factors that cause Alzheimer's disease. This disease affects mainly older people, late 50's to early 60's, and it is one that does not go away with time, but, instead, gets worse. There are three stages of Alzheimer's disease. The first stage of the disease attacks the hippocampus in the brain, which deals with memory. With this, a person affected by the disease will start forgetting things. The second stage affects their emotions, and with the third stage, they will forget how to do things essential to living, such as breathing or swallowing. What causes the initial forgetfullness, though, is what Dr. Tanzi was able to figure out. In our brains, we have many dendrites. When these tendrils come into contact with the neurons, we remember things. Along with the APP Protein, which when used, are clipped. In a normal brain, they are clipped right along the surface and all is well. But, there are other times where they are clipped a little above and a little below the surface. When this happens, a toxin is released into the brain. As this continues to happen, and more and more toxins are released into the brain, they start building up and forming plaque. The plaque then moves throughout the brain and fixates itself over the neurons in which the signals are sent, and the signal never reaches the destination. Eventually, the dendrites will pull back and die, and then they lose that memory. Along with the build up of more plaque, more memories are lost, and soon enough, the person forgets everything. This process is long, and in the years that it takes place, they lose more and more of themselves, along with the people around them.