Doctors at specialized centers can diagnose probable AD correctly 80 to 90 percent of the time. They can find out whether there are plaques and tangles in the brain only by looking at a piece of brain tissue under a microscope. It can be painful and risky to remove brain tissue while a person is alive. Doctors cannot look at the tissue until they do an autopsy, which is an examination of the body done after a person dies.
Doctors may say that a person has “probable” AD. They will make this diagnosis by finding out more about the person’s symptoms. The following is some of the information the doctor may need to make a diagnosis:
1. A Complete Medical History
The doctor may ask about the person’s general health and past medical problems. He or she will want to know about any problems the person has carrying out daily activities. The doctor may want to speak with the person’s family or friends to get more information.
2. Basic Medical Tests
Tests of blood and urine may be done to help the doctor eliminate other possible diseases. In some cases, testing a small amount of spinal fluid also may help. In addition, scientists are busy trying to develop a test to diagnose AD that will be easy and accurate.
3. Neuropsychological Tests
These are tests of memory, problem solving, attention, counting, and language. They will help the doctor pinpoint specific problems the person has.
4. Brain Scans
The doctor may want to do a special test, called a brain scan, to take a picture of the brain. There are several types of brain scans, including a computerized tomography (CT) scan, a magnetic resonance imaging (MRI) scan, or a positron emission tomography (PET) scan. By looking at a picture of the brain, the doctor will be able to tell if anything does not look normal. Information from the medical history and any test results help the doctor rule out other possible causes of the person’s symptoms. For example, thyroid gland problems, drug reactions, depression, brain tumors, and blood vessel disease in the brain can cause AD-like symptoms. Some of these other conditions can be treated.
Source: U.S Department of Health and Human Services
Public Health Service
National Institutes of Health
National Institute on Aging
Published in August 1995