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.
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 grow from 39 million in 2008 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.
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.
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. Two of the most common causes of dementia in older people are AD and vascular dementia, which is caused by a series of strokes or changes in the brain’s blood supply. Other conditions that cause memory loss or dementia include:
•medication side effects
•certain tumors and infections in the brain
•blood clots in the brain
•vitamin B12 deficiency
•some 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. Emotional problems, such as stress, anxiety, or depression, can make a person more forgetful and can be mistaken for dementia. Someone 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.