How Do Doctors Diagnose Dementia?

Medically Reviewed by Smitha Bhandari, MD on August 25, 2022
3 min read

Some symptoms of dementia can be treated with medication or physical therapy, so it can be helpful to find out what’s causing them sooner rather than later. It can make planning for the future and decisions about health care, finances, living options, and legal matters easier, too. And it gives you more time to build a good relationship with doctors and caregivers.

Your primary care doctor might work with you to figure out what’s behind your symptoms, or they might refer you to one or more of these doctors for certain tests:

  • A neurologist, who specializes in the brain and nervous system
  • A psychiatrist or another mental health specialist
  • A psychologist or neuropsychologist, who specializes in memory and mental functions
  • A geriatrician, who specializes in the care of older adults

Your primary care doctor probably will start with a physical exam and ask questions about your medical history and other things like:

  • Does dementia run in your family?
  • When did the symptoms start?
  • Have you noticed changes in behavior or personality?
  • Do you have any other medical problems, or are you taking any medications?

They’ll ask someone close to you, like a friend or family member, those same questions, too, because people with dementia aren’t always aware of their condition.

There’s no single test that will tell your doctor if you have dementia. It’s a process. You may have several of the following, then your doctor will put all the information together to make a diagnosis.

Cognitive tests: These measure your ability to think. They focus on things like memory, counting, reasoning, and language skills.

For example, your doctor might ask you to draw a clock and mark the hands at a specific time, or give you a short list of words and ask you to remember and repeat them. They also might ask you to make easy calculations, such as counting backward from 100 by seven.

Neurological tests: Your doctor will test your balance, reflexes, eye movements, and see how well your senses work.

To do this, they might ask you to push or pull their hands using your arms or to stand with your eyes closed and touch your nose. To check your reflexes, your doctor may tap a small rubber hammer against parts of your body and watch how you respond.

Lab tests: A new test called 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 PET scan) can detect plaques in the brain, which indicate a possible Alzheimer's diagnosis. In addition a regular blood test can find problems such as a lack of certain vitamins or a thyroid issue, which can affect how your brain works.

Brain scans: Your doctor may use one or more of these to get a closer look at your brain and how it’s working. They also can help rule out other problems like bleeding, a stroke, or a brain tumor:

  • CT (computerized tomography) scan: Your doctor will take a series of X-rays and put them together to make a more complete picture.
  • MRI (magnetic resonance imaging) scan: This uses powerful magnets and radio waves to make detailed images of your brain and the tissue and nerves around it.
  • PET (positron emission tomography) scan: This shows the activity in your brain and can be used to check for a certain protein (the amyloid protein) that can be a sign of Alzheimer’s disease.

Psychiatric evaluation: Your doctor will ask questions about your mood and sense of well-being to see if depression or another mental health condition might be causing symptoms of dementia.

They’ll also probably ask about any behaviors that are causing concern: When do they happen, and how long do they last? And they’ll talk with you about your relationships with your spouse, children, or friends.

It’s a good idea to put together the following for your first appointment:

  • A list of symptoms -- include everything you’re feeling, even if you don’t think it could be related to dementia
  • Any sources of major stress or recent life changes
  • A list of all medications you take, including vitamins and supplements, and the dosage
  • A list of any questions you have