Alzheimer Disease

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 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.

Alzheimer Disease Causes

We do not know exactly what causes Alzheimer disease. There is probably not one single cause, but a number of factors that come together in certain people to cause the disease.

• Most experts believe that Alzheimer disease is not a normal part of aging.
  
• While age is a risk factor for the disease, age alone does not seem to cause it.
  
• Family history is another risk factor. The disease does seem to run in some families. However, fewer than 10% of cases of Alzheimer disease are familial. Familial Alzheimer disease often occurs at a younger age, between ages 30 and 60 years. This is called early-onset familial Alzheimer disease.

 At least 3 different genes have been linked to Alzheimer disease.

• The one we know the most about controls production of a protein called apolipoprotein E (apoE), which helps in distribution of cholesterol through the body.
  
• Everyone has one of the 3 forms of the apoE gene. While one form seems to protect from AD, another form seems to increase the risk of developing the disease.
  
• The other genes—apart from ApoE—are known to be mutated in some people with the disease. These actually cause the disease in a few rare cases.
  
• Probably there are other genes that contribute to Alzheimer disease, but we haven’t found them yet.

Much of the research in Alzheimer disease has focused on why and how some people develop deposits of the abnormal protein in their brains. Once the process is understood, it may be possible to develop treatments that stop or prevent it.

Exams and Tests

Primary health care providers are able to diagnose and treat Alzheimer disease. Some health care providers specialize in the problems of older people (gerontologists) or of the brain (neurologists and psychiatrists). If you or a relative have symptoms that suggest Alzheimer disease, you may want to consult a specialist. 
 
When the health care provider hears that an elderly person is having one or more cognitive problems, he or she will probably suspect Alzheimer disease. However, many other conditions can cause dementia or dementia-like symptoms in an elderly person, including both medical and psychological problems. Many of these conditions can be reversed, or at least stopped or slowed. Therefore, it is extremely important that the person with symptoms be checked thoroughly to rule out treatable conditions.
 
The only way to confirm the diagnosis of Alzheimer disease is to look at the brain directly and to identify senile plaques and neurofibrillary tangles. This is possible only at autopsy, after a person’s death. The diagnosis in a living person is usually made on the basis of symptoms and ruling out other conditions. This is done by a combination of medical interview, physical and mental examinations, lab tests, imaging studies, and other tests.
 
The medical interview involves detailed questions about the symptoms and how they have changed over time. Your health care provider will also ask about medical problems now and in the past, family medical problems, medications, work and travel history, habits, and lifestyle.
 
A detailed physical examination is done to rule out medical problems that might cause dementia. The examination should include a mental status evaluation. This involves answering the examiner’s questions and following simple directions. In some cases, the health care provider will refer the person for neuropsychological testing.
 
Neuropsychological testing

Neuropsychological testing is the most accurate method of pinpointing and documenting a person’s cognitive problems and strengths.

• This can help give a more accurate diagnosis of the problems and thus can help in treatment planning.
  
• The testing involves answering questions and performing tasks that have been carefully prepared for this purpose. It is carried out by a specialist called a neuropsychologist.
  
• It addresses the individual’s appearance, mood, anxiety level, and experience of delusions or hallucinations.
  
• It assesses cognitive abilities such as memory, attention, orientation to time and place, use of language, and abilities to carry out various tasks and follow instructions.
  
• Reasoning, abstract thinking, and problem solving are tested.

Lab tests

These include blood tests to rule out infections, blood disorders, chemical abnormalities, hormonal disorders, and liver or kidney problems that could cause dementia symptoms.
 
Imaging studies

Brain scans cannot detect Alzheimer disease. A scan usually is necessary to rule out other conditions such as brain tumors and stroke that can also cause dementia.

• MRI or CT scan of the brain may be done to rule out other brain conditions.
  
• Single-photon emission computed tomography (SPECT) scan is used in certain cases when the diagnosis of Alzheimer disease is especially doubtful. It is especially good at detecting certain less common causes of dementia.

Other tests:

Any of these tests may be ordered as part of the workup of dementia.

• Electroencephalography (EEG) is a measurement of the electrical activity of the brain. It can be useful in some cases to rule out other conditions.
  
• Genetic testing for apolipoproteins is sometimes used in research studies of Alzheimer disease risk, but it is of little if any value in confirming the diagnosis in individual patients. Other genetic tests are also not routinely done.

• Spinal tap is a method of obtaining a sample of cerebrospinal fluid. This may be done to rule out certain other brain conditions that can cause dementia.