How is Dementia Diagnosed?

To diagnose dementia, doctors first assess whether a person has an underlying, potentially treatable, condition that may relate to cognitive difficulties. A physical exam to measure blood pressure and other vital signs, as well as laboratory tests of blood and other fluids to check levels of various chemicals, hormones, and vitamins, can help uncover or rule out possible causes of symptoms.

A review of a person’s medical and family history can provide important clues about risk for dementia. Typical questions might include asking about whether dementia runs in the family, how and when symptoms began, changes in behavior and personality, and if the person is taking certain that might cause or worsen symptoms.

The following procedures also may be used to diagnose dementia:

  • Cognitive and neurological tests. These tests are used to assess thinking and physical functioning. These include assessments of memory, problem solving, language skills, and math skills, as well as , sensory response, and reflexes.
  • Brain scans. These tests can identify, tumors, and other problems that can cause dementia. Scans also identify changes in the brain’s structure and function. The most common scans are:
    • Computed tomography (CT), which uses X-rays to produce images of the brain and other organs
    • Magnetic resonance imaging (MRI), which uses magnetic fields and radio waves to produce detailed images of body structures, including tissues, organs, bones, and nerves
    • Positron emission tomography (PET), which uses radiation to provide pictures of brain activity
  • Psychiatric evaluation. This evaluation will help determine if depression or another mental health condition is causing or contributing to a person’s symptoms.
  • Genetic tests. Some dementias are caused by a person’s genes. In these cases, a genetic test can help people know if they are at risk for dementia. It is important to talk with a genetic counselor before and after getting tested, along with family members and the doctor.
  • Blood tests. It is now possible for doctors to order a blood test to measure levels of beta-amyloid, a protein that accumulates abnormally in people with Alzheimer’s. Several other blood tests are in development. However, the availability of these diagnostic tests for Alzheimer’s and related dementias is still limited.

Early detection of symptoms is important, as some causes can be treated. However, in many cases, the cause of dementia is unknown and cannot be treated. Still, obtaining an early diagnosis can help with managing the condition and planning ahead.

Sometimes, a person with dementia will agree to donate their brain. Brain donation helps researchers study brain disorders, such as Alzheimer’s disease and related dementias, which affect millions of people. By studying the brains of people who have died, researchers learn more about how types of dementia affect the brain and how we might better treat and prevent them. When donating as part of a research study or to the NIH NeuroBioBank, there is no cost to the family for the donation and an autopsy report.

Who can diagnose dementia?

Visiting a primary care doctor is often the first step for people who are experiencing changes in thinking, movement, or behavior. However, neurologists — doctors who specialize in disorders of the brain and nervous system — are often consulted to diagnose dementia. Geriatric psychiatrists, neuropsychologists, and geriatricians may also be able to diagnose dementia. Your doctor can help you find a specialist.

If a specialist cannot be found in your community, contact the nearest medical school neurology department for a referral. A medical school hospital also may have a dementia clinic that provides expert evaluation. You can also visit the Alzheimer’s Disease Research Centers directory to see if there is an NIA-funded center near you. These centers can help with obtaining a diagnosis and medical management of conditions.