How is Alzheimers disease diagnosed?
Primary health-care professionals are able to diagnose and treat Alzheimer's disease. Some health-care professionals 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's 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's 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's 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 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.
These include blood tests to rule out infections, blood disorders, chemical abnormalities, hormonal disorders, and liver or kidney problems that could cause dementia symptoms.
Brain scans cannot detect Alzheimer's 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's disease is especially doubtful. It is especially good at detecting certain less common causes of dementia.
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's 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 (lumbar puncture) 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.