What is a Alzheimer ?
Alzheimer’s (AHLZ-high-merz) 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, suspiciousness or agitation, as well as delusions or hallucinations.
Although there is currently no cure for Alzheimer’s, new treatments are on the horizon as a result of accelerating insight into the biology of the disease. Research has also shown that effective care and support can improve quality of life for individuals and their caregivers over the course of the disease from diagnosis to the end of life.
Alzheimer disease (AD) is the most common cause of dementia in industrialized nations. Dementia is a brain disorder that interferes with a person’s ability to carry out everyday activities.
- The brain of a person with Alzheimer disease (see Multimedia file 1) has abnormal areas containing clumps (senile plaques) and bundles (neurofibrillary tangles) of abnormal proteins. These clumps and tangles destroy connections between brain cells.
- This usually affects the parts of the brain that control cognitive (intellectual) functions such as thought, memory, and language.
- Levels of certain chemicals that carry messages around the brain (neurotransmitters) are low.
- The resulting losses in intellectual ability are called dementia when they are severe enough to interfere with everyday functioning.
Alzheimer disease affects mainly people aged 60 years or older.
- The risk of developing Alzheimer disease continues to increase with age. People aged 80 years, for example, have a significantly greater risk than people aged 65 years.
- About 5 million people in the United States and more than 30 million people worldwide have Alzheimer disease. Many others have mild, or minimal, cognitive impairment, which frequently precedes dementia.
- The number of people with Alzheimer disease is expected to rise substantially in the next few decades because of the aging of the population.
- The disease affects all races and ethnic groups.
- It seems to affect more women than men.
Alzheimer disease is a progressive disease, which means that it gets worse over time. It cannot be cured or reversed by any known treatment.
- The symptoms often are subtle at first.
- Over time, people with the disease lose their ability to think and reason clearly, judge situations, solve problems, concentrate, remember useful information, take care of themselves, and even speak.
- Changes in behavior and personality are common.
- People with mild Alzheimer disease usually require close supervision and help with everyday tasks such as cooking, shopping, and paying bills.
- People with severe Alzheimer disease can do little on their own and require complete full-time care.
Because of this, Alzheimer disease is considered a major public health problem.
- The cost of caring for people with the disease is estimated at over $100 billion per year in the United States. The average yearly cost per affected person is $20,000 to $40,000, depending on the severity of the disease.
- That cost doesn’t take into account the loss of quality of life for the affected person, nor the physical and emotional toll on family caregivers
The greatest known risk factor for Alzheimer’s is increasing age. Most individuals with the disease are 65 or older. The likelihood of developing Alzheimer’s doubles about every five years after age 65. After age 85, the risk reaches nearly 50 percent.
another risk factor is family history. Research has shown that those who have a parent, brother or sister, or child with Alzheimer’s are more likely to develop Alzheimer’s. The risk increases if more than one family member has the illness. When diseases tend to run in families, either heredity (genetics) or environmental factors or both may play a role.
Scientists know genes are involved in Alzheimer’s. There are two categories of genes that can play a role in determining whether a person develops a disease. Alzheimer genes have been found in both categories:
1) Risk genes increase the likelihood of developing a disease, but do not guarantee it will happen. Scientists have so far identified one Alzheimer risk gene called apoliprotein E-e4 (APOE-e4).
APOE-e4 is one of three common forms of the APOE gene; the others are APOE-e2 and APOE-e3. APOE provides the blueprint for one of the proteins that carries cholesterol in the bloodstream.
Everyone inherits a copy of some form of APOE from each parent. Those who inherit one copy of APOE-e4 have an increased risk of developing Alzheimer’s. Those who inherit two copies have an even higher risk, but not a certainty. Scientists do not yet know how APOE-e4 raises risk. In addition to raising risk, APOE-e4 may tend to make symptoms appear at a younger age than usual.
Experts believe there may be as many as a dozen other Alzheimer risk genes in addition to APOE-e4.
2) Deterministic genes directly cause a disease, guaranteeing that anyone who inherits them will develop the disorder. Scientists have found rare genes that directly cause Alzheimer’s in only a few hundred extended families worldwide.
When Alzheimer’s disease is caused by deterministic genes, it is called “familial Alzheimer’s disease,” and many family members in multiple generations are affected. True familial Alzheimer’s accounts for less than 5 percent of cases.
Genetic tests are available for both APOE-e4 and the rare genes that directly cause Alzheimer’s. However, health professionals do not currently recommend routine genetic testing for Alzheimer’s disease. Testing for APOE-e4 is sometimes included as a part of research studies.