Causes
What causes Alzheimer’s disease?
An abnormal build-up of proteins in your brain causes Alzheimer’s disease. The build-up of these proteins — amyloid protein and tau protein — causes brain cells to die.
The human brain contains over 100 billion nerve cells and other cells. The nerve cells work together to fulfill all the communications needed to perform functions such as thinking, learning, remembering and planning.
Scientists believe that amyloid protein builds up in your brain cells, forming larger masses called plaques. Twisted fibers of another protein called tau form into tangles. These plaques and tangles block the communication between nerve cells, which prevents them from carrying out their processes.
The slow and ongoing death of the nerve cells results in the symptoms of Alzheimer’s disease. Nerve cell death starts in one area of your brain (usually in the area of your brain that controls memory — the hippocampus) and then spreads to other areas.
Despite ongoing research, scientists still don’t know what exactly causes these proteins to build up. So far, they believe that a genetic mutation may cause early-onset Alzheimer’s. They think that late-onset Alzheimer’s happens due to a complex series of brain changes that may occur over decades. A combination of genetic, environmental and lifestyle factors likely contribute to the cause.