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What is Alzheimer's disease (AD)?
Alzheimer’s disease (AD) is an irreversible, progressive brain disease that slowly destroys memory and thinking skills and, eventually, the ability to carry out the simplest tasks of daily living. In most people with AD, symptoms first appear after age 60.
AD is the most common cause of dementia among older people, but it is not a normal part of aging. Dementia refers to a decline in cognitive function that interferes with daily life and activities. AD starts in a region of the brain that affects recent memory, then gradually spreads to other parts of the brain. Although treatment can slow the progression of AD and help manage its symptoms in some people, currently there is no cure for this devastating disease.
AD is named after Dr. Alois Alzheimer, a German doctor. In 1906, Dr. Alzheimer described changes in the brain tissue of a woman who had died of an unusual mental illness. He found abnormal clumps (now called amyloid plaques) and tangled bundles of fibers (now called neurofibrillary tangles).
Today, these plaques and tangles in the brain are considered hallmarks of AD. The third main feature of AD is the gradual loss of connections between nerve cells (neurons) in the brain. This loss leads to diminished cell function and cell death.
We don’t know what starts the AD process, but we do know that damage to the brain begins as many as 10 to 20 years before any obvious signs of forgetfulness appear.
As nerve cells die throughout the brain, affected regions begin to shrink. By the final stage of AD, damage is widespread, and brain tissue has shrunk significantly.
View Video: Alzheimer's Disease ProcessThis 2-minute captioned video shows the progression of AD in the brain. You will need RealPlayer to view it. Download free RealPlayer.
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How many Americans have AD?
According to recent estimates, as many as 2.4 million to 4.5 million Americans have AD. Unless the disease can be effectively treated or prevented, the number of people with AD will increase significantly if current population trends continue. That’s because the risk of AD increases with age, and the U.S. population is aging. The number of people age 65 and older is expected to double from 36 million in 2003 to 72 million in 2030, and the number of people with AD doubles for every 5-year interval beyond age 65.
In the years to come, AD is expected to pose physical and emotional challenges for more and more families and other caregivers, in addition to those with the disease. The growing number of people with AD and the costs associated with the disease also will put a heavy economic burden on society.
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How long can a person live with AD?
AD is a slow disease that starts with mild memory problems and ends with severe brain damage. The time from diagnosis to death varies—as little as 3 or 4 years if the person is older than 80 when diagnosed to as long as 10 or more years if the person is younger. Other factors that affect how long a person will live with AD include the person’s sex, the presence of other health problems, and the severity of cognitive problems at diagnosis.
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What is dementia?
Dementia is a general term that refers to a decline in cognitive function so extensive that it interferes with daily life and activities. This loss in the ability to think, remember, and reason is not a disease itself, but a group of symptoms that often accompanies a disease or condition.
Many conditions and diseases cause dementia. Some of them can be reversed, but others cannot. AD is the most common cause of dementia in older people. Vascular dementia, caused by cognitive impairment from a stroke or other damage to the brain’s blood vessels, is the second most common form of dementia.
Other conditions that cause dementia include:
- medication side effects
- certain brain tumors
- blood clots pressing on the brain
- poor nutrition
- high fever
- thyroid, kidney, or liver disorders
Many of these conditions are temporary and reversible, but they can be serious and should be treated by a doctor as soon as possible.
Sometimes older people have emotional problems that can be mistaken for dementia. They may feel sad, lonely, worried, or bored when facing retirement or coping with the death of a spouse, relative, or friend. Adapting to these changes leaves some people feeling confused or forgetful. Supportive friends and family or professional help from a doctor or counselor can help older adults adjust to big changes.
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What is mild cognitive impairment?
Mild cognitive impairment (MCI) is a condition in which a person has memory problems greater than those expected for his or her age. However, people with MCI do not have the personality changes or cognitive problems that characterize AD.
MCI has several types. The type most associated with memory loss is called amnestic MCI. People with this condition have more memory problems than normal for their age, but their symptoms are not as severe as those of people with AD. More people with MCI go on to develop AD than people without MCI. Researchers are not yet sure why some people with MCI do not progress to AD, nor can they say who will or will not develop AD.
Other questions? Call the ADEAR Center at 1-800-438-4380 or e-mail our information specialists.
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