How is Dementia Diagnosed?

To diagnose dementia, doctors first assess whether a person has an underlying treatable condition such as abnormal thyroid function, normal pressure hydrocephalus, or a vitamin deficiency that may relate to cognitive difficulties. Early detection of symptoms is important, as some causes can be treated. In many cases, the specific type of dementia a person has may not be confirmed until after the person has died and the brain is examined.

A medical assessment for dementia generally includes:

• Medical history. Typical questions about a person’s medical and family history 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 medications that might cause or worsen symptoms.
• Physical exam. Measuring blood pressure and other vital signs may help physicians detect conditions that might cause or occur with dementia. Some conditions may be treatable.
• Neurological tests. Assessing balance, sensory response, reflexes, and other cognitive functions helps identify conditions that may affect the diagnosis or are treatable with drugs.

What Tests are Used to Diagnose Dementia?

The following procedures also may be used to diagnose dementia:

• Cognitive and neuropsychological tests. These tests are used to assess memory, problem solving, language skills, math skills, and other abilities related to mental functioning.
• Laboratory tests. Testing a person’s blood and other fluids , as well as checking levels of various chemicals, hormones, and vitamins, can help find or rule out possible causes of symptoms.
• Brain scans. These tests can identify strokes, 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 known gene defect. 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.

Who Can Diagnose Dementia?

Visiting a family 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—generally have the expertise needed to diagnose dementia. Geriatric psychiatrists, neuropsychologists, and geriatricians may also be skilled in diagnosing the condition.

If a specialist cannot be found in your community, ask the neurology department of the nearest medical school for a referral. A hospital affiliated with a medical school may also have a dementia or movement disorders clinic that provides expert evaluation.