What is Alzheimer's?
Alzheimer's disease is a brain disorder named for German physician Alois Alzheimer, who first described it in 1906. Scientists have learned a great deal about Alzheimer's disease in the century since Dr. Alzheimer first drew attention to it. Today we know that Alzheimer's:
- Is a progressive and fatal brain disease. As many as 5.3 million Americans are living with Alzheimer's disease. Alzheimer's destroys brain cells, causing memory loss and problems with thinking and behavior severe enough to affect work, lifelong hobbies or social life. Alzheimer's gets worse over time, and it is fatal. Today it is the seventh-leading cause of death in the United States.
- Is the most common form of dementia, a general term for memory loss and other intellectual abilities serious enough to interfere with daily life. Alzheimer's disease accounts for 50 to 80 percent of dementia cases. Other types of dementia include vascular dementia, mixed dementia, dementia with Lewy bodies and frontotemporal dementia.
- Has no current cure. But treatments for symptoms, combined with the right services and support, can make life better for the millions of Americans living with Alzheimer's. There is an accelerating worldwide effort under way to find better ways to treat the disease, delay its onset, or prevent it from developing.
Alzheimer's and the Brain
Just like the rest of our bodies, our brains change as we age. Most of us notice some slowed thinking and occasional problems with remembering certain things. However, serious memory loss, confusion and other major changes in the way our minds work are not a normal part of aging. They may be a sign that brain cells are failing.
The brain has 100 billion nerve cells (neurons). Each nerve cell communicates with many others to form networks. Nerve cell networks have special jobs. Some are involved in thinking, learning and remembering. Others help us see, hear and smell. Still others tell our muscles when to move. In Alzheimer's disease, as in other types of dementia, increasing numbers of brain cells deteriorate and die.
The Role of Plaques and Tangles
Two abnormal structures called plaques and tangles are prime suspects in damaging and killing nerve cells. Plaques and tangles were among the abnormalities that Dr. Alois Alzheimer saw in the brain of Auguste D., although he called them different names.
Plaques build up between nerve cells. They contain deposits of a protein fragment called beta-amyloid. Tangles are twisted fibers of another protein called "tau."
Tangles form inside dying cells. Though most people develop some plaques and tangles as they age, those with Alzheimer's tend to develop far more. The plaques and tangles tend to form in a predictable pattern, beginning in areas important in learning and memory and then spreading to other regions.
Scientists are not absolutely sure what role plaques and tangles play in Alzheimer's disease. Most experts believe they somehow block communication among nerve cells and disrupt activities that cells need to survive.
Early-stage and Younger-onset Alzheimer's Disease
Early-stage is the early part of Alzheimer's disease when problems with memory, thinking and concentration may begin to appear in a doctor's interview or medical tests. Individuals in the early-stage typically need minimal assistance with simple daily routines. At the time of a diagnosis, an individual is not necessarily in the early stage of the disease; he or she may have progressed beyond the early stage.
The term younger-onset refers to Alzheimer's that occurs in a person under age 65. People who have younger-onset dementia may be in any stage of dementia – early, middle or late. Experts estimate that some 500,000 people in their 30s, 40s and 50s have Alzheimer's disease or a related dementia.