An early, accurate diagnosis of Alzheimer's disease helps patients and their families plan for the future. It gives them time to discuss care options while the patient can still take part in making decisions. And even though no drug can slow the onset or the progression of Alzheimer's, early diagnosis offers the best chance to treat the symptoms of the disease.
Today, the only definite way to diagnose Alzheimer's disease is to find out whether there are plaques and tangles in brain tissue. To look at brain tissue, doctors must wait until they do an autopsy, which is an examination of the body done after a person dies. Therefore, doctors can only make a diagnosis of "possible" or "probable" Alzheimer's disease while the person is still alive. At specialized centers, doctors can diagnose Alzheimer's disease correctly up to 90 percent of the time.
Doctors use several tools to diagnose "probable" Alzheimer's disease:
- A complete medical history with questions about the person's general health, past medical problems, and any difficulties carrying out daily activities.
- Medical tests, such as tests of blood, urine or spinal fluid.
- Tests to measure memory, problem solving, attention, counting, and language.
- Brain scans that allow the doctor to look at a picture of the brain to see if anything does not look normal.
Sometimes, these test results help the doctor find other possible causes of the person's symptoms. For example, thyroid problems, drug reactions, depression, brain tumors, and blood vessel disease in the brain can cause symptoms similar to those of Alzheimer's. Some of these other conditions can be treated successfully.
Recently, scientists have focused on a type of memory change called mild cognitive impairment, or MCI. MCI is different from both Alzheimer's disease and age-related memory change. People with MCI have ongoing memory problems but do not have noticeable problems in other areas like confusion, attention problems, and difficulty with language.