What Tests Are Used to Diagnose Alzheimer’s Disease?
In spite of the fact that it is so common, Alzheimer’s disease often goes unrecognized or is misdiagnosed in its early stages. Many doctors and nurses, patients, and family members mistakenly view the early symptoms of Alzheimer’s disease as the inevitable consequences of aging.
Some disorders that can result in dementia — such as depression, poor nutrition, and drug interactions — are curable, but Alzheimer’s disease is not. Therefore, it is very important to diagnose the cause of the dementia early and correctly. In addition, some Alzheimer’s disease symptoms — such as incontinence and depression — can be effectively treated, so it’s better to identify these as soon as possible.
An early and accurate diagnosis of the cause of dementia is important for the following reasons:
- To rule out Alzheimer’s disease and ease the patient’s and family’s concern.
- To identify any treatable condition and initiate treatment as appropriate.
- To identify Alzheimer’s disease at the earliest possible stage; this gives the patient and family time to plan for the future needs and care of the patient. This also allows the patient to start using some medicines that are only useful in the earlier stages of Alzheimer’s.
Alzheimer’s disease cannot be definitely diagnosed until after death, when the brain can be closely examined for certain microscopic changes caused by the disease.
However, through thorough testing and a “process of elimination,” doctors today can diagnose what they refer to as probable Alzheimer’s disease with almost 90% accuracy.
The following things may be used to help make a diagnosis of Alzheimer’s disease:
Patient History
A history from the patient helps the doctor assess a person’s past and current health situation. It also helps the doctor evaluate whether there are any medical problems, develop a plan of treatment, and monitor the patient’s health over time.
During this evaluation, the doctor asks the person a series of questions. A thorough patient history includes:
- Patient’s identifying information.
- Information about the main problem, including any difficulties in daily living.
- Information about other symptoms.
- History of any current illness.
- Past medical history.
- Medications being taken.
- Current health status.
- Psychosocial history — like marital status, living conditions, employment, sexual history, important life events.
- Mental state — this is a series of questions that the doctor will ask to determine if the person is experiencing any evidence of psychiatric illness, like depression.
- Family history (including any illnesses that seem to run in the family).
Mini-Mental State Exam
A mini-mental state exam is a very brief test that the doctor can use to test a person’s problem solving skills, attention span, counting skills and memory. It will give the doctor insight into whether there has been damage to different areas of the brain.
Physical Exam
The physical exam is part of the patient care process. The exam enables the doctor to assess the overall physical condition of the patient. If the patient has a medical complaint, the physical exam provides the doctor with more information about the problem, which helps him determine an appropriate plan of treatment. The physical exam includes an examination of the following:
- Vital signs (temperature, blood pressure, pulse)
- Height and weight
- Skin
- Head, eyes, ears, nose
- Throat/neck
- Chest, including lungs and heart
- Breasts
- Abdomen
- Bones and muscles
- Neurological evaluation
- Rectal/genital area
Chest X-ray
An X-ray is a test in which an image of the body is created by using low doses of radiation. X-rays can be used to diagnose a wide range of conditions, from bronchitis to broken bones. When viewing X-ray images of the chest, doctors can the view the structures inside the chest, including the heart, lungs, and bones. This test may be used by the doctor to help rule out other disorders that may be causing symptoms similar to those of Alzheimer’s disease.
Laboratory Tests
When a doctor is diagnosing an illness, he or she often orders laboratory tests on certain fluids and tissue samples from the body. These tests can help identify problems and diseases.
There are hundreds of laboratory tests available to help doctors make a diagnosis. The most common are blood tests and urinalysis. Blood tests involve a series of tests routinely done on blood to look for abnormalities associated with various diseases and disorders.
Blood tests may also be used to look for the presence of a specific gene that has been identified as a risk factor for Alzheimer’s disease.
A urinalysis is a test in which a urine sample is evaluated to detect abnormalities, such as abnormal levels of sugar or protein. This test may be used by the doctor to help rule out other disorders that may be causing symptoms similar to those of Alzheimer’s disease.
In some cases, obtaining and testing a small amount of spinal fluid may be helpful.
CT Scan
CT (computed tomography) scanning is a technique in which multiple X-rays of the body are taken from different angles in a very short period of time. These images are then fed into a computer, which creates a series of images that look like “slices” through the body. CT scans can show certain changes that are characteristic of Alzheimer’s disease in its later stages. These changes include a reduction in the size of the brain, referred to as atrophy.
Magnetic Resonance Imaging (MRI)
Magnetic resonance imaging, usually called MRI, is a test that produces very clear pictures, or images, of the human body without using X-rays. Instead, MRI uses a large magnet, radio waves, and a computer to produce these images. MRI is beneficial in ruling out other causes of dementia, such as tumors or strokes. It also may help to show the structural and functional changes in the brain that are associated with Alzheimer’s disease.
Electroencephalography (EEG)
Electroencephalography (EEG) is a medical technique that measures brain function by analyzing the electrical activity generated by the brain. This activity is measured through special electrodes applied to the scalp. EEG can be used repeatedly in adults and children with virtually no risks and is helpful in diagnosing seizures, which may be contributing to behavioral changes seen in the patient.
Electrocardiogram (ECG)
An electrocardiogram (ECG) is a recording of the heart’s electrical activity. This activity is registered as a graph or series of wavy lines on a moving strip of paper. This gives the doctor important information about the heart. For example, it can show the heart’s rate and rhythm. It also can help show decreased blood flow, enlargement of the heart, or the presence of damage due to a current or past heart attack. This test may be used by the doctor to help rule out other conditions that may be causing symptoms similar to those of Alzheimer’s disease.
Neuropsychological Testing
Neuropsychological testing studies the relationship between the brain and behavior. It is used when the patient is having serious problems with memory, concentration, remembering words and names, understanding language, visual-spatial issues, and a variety of other symptoms. These tests help in the diagnosis and treatment of conditions that affect thinking, emotion, and behavior. These include Alzheimer’s disease, various psychiatric problems, like depression and anxiety, problems caused by medicines, substance abuse, strokes, and tumors. Neuropsychological tests accompany a comprehensive interview with the patient and may include tests to assess memory, language, the ability to plan and reason, and the ability to modify behavior, as well as assessments of personality and emotional stability. Neuropsychological testing also can help the doctor and family better understand the effect of a disorder on a patient’s everyday functioning.
There are additional tests that may be done to help diagnose and monitor the progression of Alzheimer’s disease. The following tests are not done routinely and are more often used for research purposes:
Positron Emission Tomography (PET) Scan
PET scanning is a three-dimensional imaging technique that allows a doctor to examine the heart, brain, or other internal organs. PET scans also can show how the organs are functioning; unlike X-ray, CT, or MRI, which show only body structure. PET is particularly useful for the detection of cancer and coronary artery disease and can provide information to pinpoint and evaluate diseases of the brain. PET imaging can show the region of the brain that is causing a patient to have seizures and is useful in evaluating brain diseases like Alzheimer’s, Huntington’s, and Parkinson’s. PET scans can show the difference in brain activity between a normal brain and one affected by Alzheimer’s disease; it can also help differentiate Alzheimer’s disease from other forms of dementia.
Single Photon Emission Computed Tomography (SPECT) Scan
SPECT is a technique for creating very clear, three-dimensional pictures of a major organ, such as the brain or heart. SPECT scans involve the injection of a very small amount of a radioactive substance. Energy from the radioactive substance in the body is detected by a special camera, which then takes the pictures. SPECT can be used to see how blood flows in certain regions of the brain and is useful in evaluating specific brain functions. This may reveal abnormalities that are characteristic of Alzheimer’s disease.
Magnetic Resonance Spectroscopy Imaging (MRSI)
MRSI is a test that allows the doctor to observe certain substances throughout the brain without the use of radioactive materials. MRSI is an imaging technique that is used to study changes caused by brain tumors, strokes, seizure disorders, Alzheimer’s disease, depression, and other diseases affecting the brain.
Original Source: http://www.webmd.com/alzheimers/guide/making-diagnosis