The Alzheimer's Disease Education and Referral (ADEAR) Center
What is Alzheimer's disease (AD)?
• Alzheimer’s disease (AD) is a progressive brain disease that affects 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.
• AD starts in a region of the brain that affects recent memory, then gradually spreads to other parts of the brain.
How many Americans have AD?
• According to recent estimates, as many as 2.4 million to 4.5 million Americans have AD.
• 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.
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What is dementia?
• Dementia is a general term that refers to a extensive decline in cognitive function.
• 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.
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.
• 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 those without MCI within a certain timeframe. However, not everyone who has MCI develops AD.
• Studies are underway to learn why some people with MCI progress to AD and others do not.
What causes AD?
• Scientists don’t yet fully understand what causes AD, but it is clear that it develops because of a complex series of events that take place in the brain over a long period of time.
• It is likely that the causes include genetic, environmental, and lifestyle factors.
• As people differ in their genetic make-up and lifestyle, the importance of these factors for preventing or delaying AD differs from person to person.
• Genetics play a role in some people with AD. A rare type of AD, called early-onset AD, affects people ages 30 to 60. Some cases of early-onset AD, called familial AD, are inherited. Familial AD is caused by mutations (permanent changes) in three genes. Offspring in the same generation have a 50-50 chance of developing familial AD if one of their parents had it.
• Most cases of AD are late-onset AD, which develops after age 60. Although a specific gene has not been identified as the cause of late-onset AD, genetic factors do appear to increase a person’s risk of developing the disease.
• Research suggests that certain lifestyle factors, such as a nutritious diet, exercise, social engagement, and mentally stimulating pursuits, might help to reduce the risk of cognitive decline and AD.
Can AD be prevented?
We can’t control some risk factors for AD such as age and genetic profile. But scientists are studying a number of other factors that could make a difference. Only further research will reveal whether these health, lifestyle, and environmental factors can help prevent AD. Some of these factors are: physical activity, dietary factors such as antioxidants and DHA, and damage to the vascular system.
What are the symptoms of AD?
The course of AD is not the same in every person with the disease, but symptoms seem to develop over the same general stages.
Very early signs and symptoms
Memory problems are one of the first signs of AD. Some people with mild AD have a condition called amnestic mild cognitive impairment (MCI). People with MCI have more memory problems than normal for people 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.
As AD progresses, memory loss continues and changes in other cognitive abilities appear. Symptoms in this stage can include:
• getting lost
• trouble handling money and paying bills
• repeating questions
• taking longer than before to complete normal daily tasks
• poor judgment
• losing things or misplacing them in odd places
• mood and personality changes
In most people with AD, symptoms first appear after age 60. AD is often diagnosed at this stage.
In moderate AD, damage occurs in areas of the brain that control language, reasoning, sensory processing, and conscious thought. Symptoms may include:
• increased memory loss and confusion
• problems recognizing family and friends
• inability to learn new things
• difficulty carrying out tasks that involve multiple steps (such as getting dressed)
• problems coping with new situations
• delusions and paranoia
• impulsive behavior
People with severe AD cannot communicate and are completely dependent on others for their care. Near the end, the person with AD may be in bed most or all of the time. Their symptoms often include:
• inability to recognize oneself or family
• inability to communicate
• weight loss
• skin infections
• difficulty swallowing
• groaning, moaning, or grunting
• increased sleeping
• lack of control of bowel and bladder
How is AD diagnosed?
• The only definite way to diagnose AD is with an autopsy, which is an examination of the body done after a person dies.
• However, doctors can determine fairly accurately whether a person who is having memory problems has “possible AD” (the symptoms may be due to another cause) or “probable AD” (no other cause for the symptoms can be found).
• To diagnose AD, doctors:
• ask questions about a person’s overall health, past medical problems, ability to carry out daily activities, and changes in be havior and personality
• conduct tests of memory, problem solving, attention, counting, and language skills
• carry out medical tests, such as tests of blood, urine, or spinal fluid
• perform brain scans, such as a computed tomography (CT) scan or magnetic resonance imaging (MRI) test
• These tests may be repeated to give doctors information about how the person’s memory is changing over time.
Why is early diagnosis important?
• Having an early diagnosis and starting treatment in the early stages of AD can help preserve function for months to years, even though the underlying AD process cannot be changed.
• Having an early diagnosis also helps patients and their families:
• plan for the future
• make living arrangements
• take care of financial and legal matters
• develop support networks
• Finally, an early diagnosis can provide greater opportunity for people with AD to get involved in clinical trials. Clinical trials are research studies in which scientists test the safety, side effects, or effectiveness of a medication or other intervention.
What new methods for diagnosing AD are being studied?
• Scientists are exploring ways to help physicians diagnose AD earlier and more accurately. The ultimate goal is a reliable, valid, inexpensive, and early diagnostic test that can be used in any doctor’s office.
• Some studies focus on changes in personality and mental functioning, measured through memory and recall tests, that might point to early AD or predict which individuals are at higher risk of developing AD in the future. Other studies are examining the relationship between early damage to brain tissue and outward clinical signs. Still others are looking at changes in blood and cerebrospinal fluid that may indicate the progression of AD.
• One of the most exciting areas of ongoing diagnostic research is neuroimaging. Scientists have developed sophisticated imaging systems that may help measure the earliest changes in brain function or structure to identify people in the very first stages of AD—well before they develop apparent signs or symptoms.
How is AD treated?
• AD is a complex disease, and no single “magic bullet” is likely to prevent or cure it. That’s why current treatments focus on several different issues, including helping people maintain mental function, managing behavioral symptoms, and slowing AD.
• AD research has developed to a point where scientists can look beyond treating symptoms to think about delaying or preventing AD by addressing the underlying disease process. Scientists are looking at many possible interventions, such as treatments for heart disease and type 2 diabetes, immunization therapy, cognitive training, changes in diet, and physical activity.
What drugs are currently available to treat AD?
• No treatment has been proven to stop AD.
• The U.S. Food and Drug Administration has approved four drugs to treat AD. For people with mild or moderate AD, donepezil (Aricept®), rivastigmine (Exelon®), or galantamine (Razadyne®) may help maintain cognitive abilities and help control certain behavioral symptoms for a few months to a few years. Donepezil can be used for severe AD, too. Another drug, memantine (Namenda®), is used to treat moderate to severe AD. However, these drugs don’t stop or reverse AD and appear to help patients only for months to a few years.
• These drugs work by regulating neurotransmitters, the chemicals that transmit messages between neurons. They may help maintain thinking, memory, and speaking skills and may help with certain behavioral problems.
• Other medicines may ease the behavioral symptoms of AD—sleeplessness, agitation, wandering, anxiety, anger, and depression. Treating these symptoms often makes patients more comfortable and makes their care easier for caregivers.
What potential new treatments are being researched?
• Scientists are very interested in the toxic effects of beta-amyloid—a part of amyloid precursor protein found in deposits (plaques) in the brains of people with AD.
• Studies have moved forward to the point that researchers are carrying out preliminary tests in humans of potential therapies aimed at removing beta-amyloid, halting its formation, or breaking down early forms before they can become harmful.
• The aging process
• Some age-related changes may make AD damage in the brain worse.
• Researchers think that inflammation may play a role in AD. Studies have suggested that common nonsteroidal anti-inflammatory drugs (NSAIDs) might help slow the progression of AD, but clinical trials so far have not shown a benefit from these drugs. Researchers are continuing to look at how other NSAIDs might affect the development or progression of AD.
• Scientists are also looking at free radicals, which are oxygen or nitrogen molecules that combine easily with other molecules. The production of free radicals can damage nerve cells. The discovery that beta-amyloid generates free radicals in some AD plaques is a potentially significant finding in the quest to understand AD better.
• Heart disease and diabetes
• Research has begun to tease out relationships between AD and vascular diseases, which affect the body’s blood vessels.
• Some scientists have found that some chronic conditions that affect the vascular system, such as heart disease and diabetes, have been tied to declines in cognitive function or increased AD risk.
• Several clinical trials are studying whether treatments for these diseases can improve memory and thinking skills in people with AD or mild cognitive impairment.
• Lifestyle factors
• A number of studies suggest that factors such as a healthy diet, exercise, and social engagement may be related to the risk of cognitive decline and AD.
• Some studies in older people have shown that higher levels of physical activity or exercise are associated with a reduced risk of AD. Clinical trials are underway to study the relationship of exercise to healthy brain aging and the development of AD.
• Scientists have also studied whether diet may help preserve cognitive function or reduce AD risk. Some studies have found that a “Mediterranean diet” was associated with a reduced risk of AD. To confirm the results, scientists are conducting clinical trials to examine the relationship between specific dietary components and cognitive function and AD.
• Studies are looking into many other possible treatments, including hormones and cognitive training, to see if they might improve thinking skills in people with AD or even prevent AD in people who are at risk.
• What are clinical trials?
• People who want to help scientists test possible treatments may be able to take part in clinical trials, which are research studies that test the safety, side effects, or effectiveness of a medication or other intervention in humans.
• Study volunteers help scientists learn about the brain in healthy aging as well as what happens in AD.
• Results of AD clinical trials are used to improve prevention and treatment approaches.