Alzheimer's: How is it Diagnosed?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 must make a diagnosis of “possible” or “probable” Alzheimer’s disease.

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 includes information about the person’s general health, past medical problems, and any difficulties the person has carrying out daily activities.
  • Medical tests – such as tests of blood, urine, or spinal fluid – help the doctor find other possible diseases causing the symptoms.
  • Neuropsychological tests measure memory, problem solving, attention, counting, and language.
  • Brain scans allow the doctor to look at a picture of the brain to see if anything does not look normal.

Information from the medical history and test results help the doctor rule out 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 Alzheimer’s disease-like symptoms. Some of these other conditions can be treated successfully.

Other possible medical or cognitive problems should be ruled out before a diagnosis of Alzheimer’s disease is made. This may involve additional testing, such as psychological or neuropsychological testing. Such testing can also help identify the specific deficits or challenges the person may be experiencing with Alzheimer’s disease.

What is the outlook for someone diagnosed with Alzheimer’s disease?

The course the disease takes and how fast changes occur vary from person to person. On average, Alzheimer’s disease patients live from 8 to 10 years after they are diagnosed, though the disease can last for as many as 20 years.

The important thing to remember is that a person with Alzheimer’s still has a long life ahead of them. It means planning for a decade or two of their life, including when a person’s memory isn’t as strong as it was when they were disease-free.

Why is early diagnosis of Alzheimer’s important?

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.

Early diagnosis also offers the best chance to treat the symptoms of the disease. While Alzheimer’s is a degenerative disease with no known cure at this time, symptoms of the disease can be treated early on, usually with medication.