Alzheimer's disease is a neurological disorder in which the death of brain cells causes memory loss and cognitive decline. A neurodegenerative type of dementia, the disease starts mild and gets progressively worse.
In the US, the most recent census has enabled researchers to give estimates of how many people have Alzheimer's disease. In 2010, some 4.7 million people of 65 years of age and older were living with Alzheimer's disease in the US.
The 2013 statistical report from the Alzheimer's Association gives a proportion of the population affected - just over a tenth of people in the over-65 age group have the disease in the US. In the over-85s, the proportion goes up to about a third.
As our dementia page outlines, there is a handful of different types, but Alzheimer's disease is the problem behind most cases of memory loss and cognitive decline.
Like all types of dementia, Alzheimer's is caused by brain cell death. It is a degenerative disease, which means there is progressive brain cell death that happens over a course of time.
The total brain size shrinks with Alzheimer's - the tissue has progressively fewer nerve cells and connections.
In the Alzheimer's disease process, progressing from the normal brain to increasing dementia changes, the Alzheimer's Association has produced a journey of 16 slides.
Some things are more commonly associated with Alzheimer's disease - not seen so often in people without the disorder. These factors may therefore have some direct connection. Some are preventable or modifiable factors (for example, reducing the risk of diabetes or heart disease may in turn cut the risk of dementia).
For doctors to make an initial diagnosis of Alzheimer's disease, they must first be satisfied that there is dementia - guidelines spell out what dementia consists of. It involves cognitive or behavioral symptoms that show a decline from previous levels of "functioning and performing" and interfere with ability "to function at work or at usual activities.
There is no known cure for Alzheimer's disease - the death of brain cells in the dementia cannot be halted or reversed.
There is, however, much backing for therapeutic interventions to help people live with Alzheimer's disease more ably.
Alzheimer’s disease is an irreversible, progressive brain disease that slowly destroys memory and thinking skills, and eventually even the ability to carry out the simplest tasks. In most people with Alzheimer’s, symptoms first appear after age 65. Estimates vary, but experts suggest that as many as 5 million Americans age 65 and older may have Alzheimer’s disease.
Alzheimer’s disease is the most common cause of dementia among older people. Dementia is the loss of cognitive functioning—thinking, remembering, and reasoning—and behavioral abilities, to such an extent that it interferes with a person’s daily life and activities. Dementia ranges in severity from the mildest stage, when it is just beginning to affect a person’s functioning, to the most severe stage, when the person must depend completely on others for basic activities of daily living.Changes in the Brain in Alzheimer’s DiseaseSigns and Symptoms
Alzheimer’s disease is an irreversible, progressive brain disease that slowly destroys memory and thinking skills, and eventually even the ability to carry out the simplest tasks. In most people with Alzheimer’s, symptoms first appear after age 65. Estimates vary, but experts suggest that as many as 5 million Americans age 65 and older may have Alzheimer’s disease.
Alzheimer’s disease is the most common cause of dementia among older people. Dementia is the loss of cognitive functioning—thinking, remembering, and reasoning—and behavioral abilities, to such an extent that it interferes with a person’s daily life and activities. Dementia ranges in severity from the mildest stage, when it is just beginning to affect a person’s functioning, to the most severe stage, when the person must depend completely on others for basic activities of daily living.
Alzheimer’s disease is an irreversible, progressive brain disease that slowly destroys memory and thinking skills, and eventually even the ability to carry out the simplest tasks. In most people with Alzheimer’s, symptoms first appear after age 65. Estimates vary, but experts suggest that as many as 5 million Americans age 65 and older may have Alzheimer’s disease.
Alzheimer’s disease is the most common cause of dementia among older people. Dementia is the loss of cognitive functioning—thinking, remembering, and reasoning—and behavioral abilities, to such an extent that it interferes with a person’s daily life and activities. Dementia ranges in severity from the mildest stage, when it is just beginning to affect a person’s functioning, to the most severe stage, when the person must depend completely on others for basic activities of daily living.
Alzheimer’s disease is named after Dr. Alois Alzheimer. In 1906, Dr. Alzheimer noticed changes in the brain tissue of a woman who had died of an unusual mental illness. Her symptoms included memory loss, language problems, and unpredictable behavior. After she died, he examined her brain and found many abnormal clumps (now called amyloid plaques) and tangled bundles of fibers (now called neurofibrillary tangles). Plaques and tangles in the brain are two of the main features of Alzheimer’s disease. The third is the loss of connections between nerve cells (neurons) in the brain.
Alzheimer’s disease is complex, and it is unlikely that any one intervention will be found to delay, prevent, or cure it. That’s why current approaches in treatment and research focus on several different aspects, including helping people maintain mental function, managing behavioral symptoms, and slowing or delaying the symptoms of disease.