Alzheimer’s disease is a progressive brain disorder that gradually destroys a person’s memory and ability to learn, reason, make judgments, communicate and carry out daily activities. As Alzheimer’s progresses, individuals may also experience changes in personality and behavior, such as anxiety, and suspiciousness or, as well as delusions or hallucinations.
Although there is currently no cure for Alzheimer’s, new treatments are on the way. Research has also shown that effective care and support can improve quality of life for individuals over the course of the disease from diagnosis to the end of life.
Alzheimer’s is the leading cause of dementia, a group of conditions that all gradually destroy brain cells and lead to progressive decline in mental function. Vascular dementia, another common form, results from reduced blood flow to the brain’s nerve cells. In some cases, Alzheimer’s disease and vascular dementia can occur together in a condition called “mixed dementia.
Alzheimer’s disease advances at widely different rates. The extent of the illness may be from 3 to 20 years. The areas of the brain that control memory and thinking skills are affected first, but as the disease progresses, cells die in other regions of the brain. Eventually, the person with Alzheimer’s will need complete care. If the individual has no other serious illness, the loss of brain function itself will cause death.
Scientists believe that whatever triggers Alzheimer’s disease begins to damage the brain years before symptoms appear. When symptoms emerge, nerve cells that process, store and retrieve information have already begun to collapse and die. Amyloidal plaques are clumps of protein that build up outside the brain’s nerve cells. Tangles are twisted strands of another protein that form inside cells. Scientists do not yet know whether plaques or tangles cause Alzheimer’s.
The greatest known risk factors for late-onset Alzheimer’s are increasing age and a family history of the disease. The likelihood of developing late-onset Alzheimer’s approximately doubles every five years after age 65. By age 85, the risk reaches nearly 50 percent. Scientists have so far discovered one gene that increases risk for late-onset disease.
Rare, ancestral types of Alzheimer’s found in a few hundred families worldwide have been linked to specific genes. Individuals who inherit these genes are virtually certain to develop the disease, usually before age 65, and sometimes as early as their 30s or 40s.
Some change in memory is normal as we grow older, but the symptoms of Alzheimer’s disease are more than simple lapses in memory. People with Alzheimer’s experience difficulties communicating, learning, thinking and reasoning — problems severe enough to have an impact on an individual’s work, social activities and family life.
There is no cure for Alzheimer’s disease. However, there are several drug treatments that may improve or stabilize symptoms and several care strategies and activities that may minimize or prevent behavioral problems. Researchers continue to look for new treatments to alter the course of the disease and other strategies to improve the quality of life for people with dementia.
Experts have recognized common patterns of symptom progression that occur in many individuals with Alzheimer’s disease and developed several methods of “staging” based on these patterns. Progression of symptoms corresponds in a general way to the basic nerve cell falling apart that takes place in Alzheimer’s disease. Nerve cell damage typically begins with cells involved in learning and memory and gradually spreads to cells that control every aspect of thinking, judgment, and behavior. The damage eventually affects cells that control and coordinate movement.
Staging systems provide useful frames of reference for understanding how the disease may unfold and for making future plans. But it is important to note that all stages are artificial benchmarks in a continuous process that can vary greatly from one person to another. Not everyone will experience every symptom and symptoms may occur at different times in different individuals. People with Alzheimer’s live an average of 8 years after diagnosis, but may survive anywhere from 3 to 20 years.
