Alzheimer's Disease: How It’s Diagnosed

Medically Reviewed by Christopher Melinosky, MD on April 05, 2023
Written by WebMD Editorial Contributors
3 min read

Alzheimer’s disease isn’t part of normal aging. If you think you or a loved one might be showing symptoms of the disease, it’s important to see a doctor to get a diagnosis. Some warning signs to get checked are memory loss, behavior changes, or trouble with speech and decision-making.

But Alzheimer’s has many of the same symptoms as other common conditions. Those include depression, vitamin deficiency, and taking medications that don’t work well together. A doctor can find out if the symptoms are happening because of Alzheimer’s or due to something else that’s easier to treat.

An early and accurate diagnosis can also give you or your loved one time to plan for the future. You can start using some medicines that help people in the earlier stages of Alzheimer's control some of their symptoms for a while, as well. On average, these drugs keep symptoms from getting worse for about 6 to 12 months in about half of the people who take them.

Doctors can’t definitely diagnose Alzheimer's disease until after death, when they can closely examine the brain under a microscope. But they can use tests to rule out other conditions that might cause the same symptoms.

Here’s what you can expect when you or your loved one is diagnosed with Alzheimer’s.

Your doctor will do a physical exam and ask questions about your past and current health. They’ll want to know:

  • Your symptoms, including any trouble you have with everyday tasks
  • Other medical conditions you have now or had before
  • Medications you take
  • Your personal history, like your marital status, living conditions, employment, sexual history, and important life events
  • Your mental state. The doctor will ask you a series of questions that help them figure out if you’re having a mental health problem, like depression.
  • Family history, including any illnesses that seem to run in the family

This is a brief test that checks your:

  • Problem-solving skills
  • Attention span
  • Counting skills
  • Memory

These tests will help your doctor know whether there are problems with the areas of your brain involved in learning, memory, thinking, or planning skills.

A Precivity AD test looks at the amounts of proteins such as beta amyloid and Apo E in blood. The presence or absence helps determine the probability of whether an imaging study (like a CT or PET scan) can detect plaques in the brain and lead to an Alzheimer’s diagnosis.  

In CT (computed tomography) a machine takes X-rays of your body from many different angles in a very short period of time. A computer turns the scans into a series of images that look like "slices" through the body. CT scans can show brain changes that are common in the later stages of Alzheimer's.

MRI makes very clear pictures of your body using a large magnet, radio waves, and a computer. It can help doctors see if a tumor or a stroke has caused symptoms that look like Alzheimer’s. It also may help to show the brain changes that are linked to the disease.

This studies the relationship between the brain and behavior. It helps in the diagnosis and treatment of conditions that affect thinking, emotion, and behavior, including Alzheimer’s.

Doctors give you these tests along with a thorough interview. They may also give you other tests to check memory, language, the ability to plan and reason, and the ability to change behavior.

Neuropsychological testing also can help the doctor and your family better understand the effect of a disorder on your everyday life.

PET uses radioactive tracers such as flortaucipir (Tauvid) to help map areas of your brain. It can help detect protein plaques which are associated with Alzheimers. Because of their cost, they are currently not covered by insuranc