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How Is Alzheimer's Disease Diagnosed?

Doctors use several methods and tools to help determine if a person with thinking or memory problems has Alzheimer’s disease. To diagnose Alzheimer’s, doctors may:Doctor examining brain scans

  • Ask the person experiencing symptoms, as well as a family member or friend, questions about overall health, use of prescription and over-the-counter medicines, diet, past medical problems, ability to carry out daily activities, and changes in behavior and personality.
  • Conduct tests of memory, problem solving, attention, counting, and language.
  • Order blood, urine, and other standard medical tests that can help identify other possible causes of the problem.
  • Administer a psychiatric evaluation to determine if depression or another mental health condition is causing or contributing to a person's symptoms.
  • Collect cerebrospinal fluid (CSF) via a spinal tap and measure the levels of proteins associated with Alzheimer’s and related dementias.
  • Perform brain scans, such as computed tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (PET), to support an Alzheimer’s diagnosis or rule out other possible causes for symptoms.

Doctors may want to repeat these tests to help best determine how the person’s memory and other cognitive functions are changing over time. The tests can also help diagnose other causes of memory problems, such as stroke, tumor, Parkinson’s disease, sleep disturbances, side effects of medication, an infection, or another type of dementia. Some of these conditions may be treatable and possibly reversible.

People with memory problems should return to the doctor every six to 12 months.

Before the early 2000s, the only sure way to know whether a person had Alzheimer’s disease was through autopsy, a procedure that is performed after death. Thanks to advances in research, lab and imaging tests are now available to help a doctor or researcher see biological signs of the disease, or biomarkers, in a living person. For example, it is now possible for many doctors, dependent on state-specific availability reflecting U.S. Food and Drug Administration guidelines, to order a blood test to measure levels of beta-amyloid, a protein that accumulates abnormally in the brains of people with Alzheimer’s. Several other blood tests are in development. At present, blood test results alone should not be used to diagnose dementia but may be taken into consideration along with other tests. However, the availability of these diagnostic tests is still limited. NIA-supported research teams continue to study options for faster, less-expensive, and less-invasive ways to diagnose Alzheimer’s.

Learn more about biomarkers and Alzheimer’s detection and research.

What happens if a doctor thinks it's Alzheimer's disease?

If a primary care doctor suspects Alzheimer’s, he or she may refer the patient to a specialist who can provide a detailed diagnosis or further assessment. Specialists include:

  • Geriatricians, who manage health care in older adults and know how the body changes as it ages and whether symptoms indicate a serious problem.
  • Geriatric psychiatrists, who specialize in the mental and emotional problems of older adults and can assess memory and thinking problems.
  • Neurologists, who specialize in abnormalities of the brain and central nervous system and can conduct and review brain scans.
  • Neuropsychologists, who can conduct tests of memory and thinking.

Memory clinics and centers, including Alzheimer’s Disease Research Centers, offer teams of specialists who work together to diagnose the problem. In addition, these specialty clinics or centers often have access to the equipment needed for brain scans and other advanced diagnostic tests.

What are the benefits of an early Alzheimer's diagnosis?

Alzheimer’s disease slowly worsens over time. People living with this disease progress at different rates, from mild Alzheimer’s, when they first notice symptoms, to severe, when they are completely dependent on others for daily, routine care such as feeding oneself.

Early, accurate diagnosis is beneficial for several reasons. While there is no cure, medicines are emerging to treat the progression of Alzheimer's. There are also medicines available to treat some symptoms of Alzheimer’s, along with coping strategies to manage behavioral issues. Most medicines currently available work best for people in the early or middle stages of the disease. Learn more about Alzheimer’s treatments.

In addition, having an early diagnosis helps people with Alzheimer’s and their families:

An early diagnosis also provides people with more opportunities to participate in clinical trials or other research studies testing possible new treatments for Alzheimer’s.

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For more information about Alzheimer's

NIA Alzheimer’s and related Dementias Education and Referral (ADEAR) Center
The NIA ADEAR Center offers information and free print publications about Alzheimer’s and related dementias for families, caregivers, and health professionals. ADEAR Center staff answer telephone, email, and written requests and make referrals to local and national resources.
Explore the website for information and resources on Alzheimer’s and related dementias from across the federal government.

National Library of Medicine

This content is provided by the NIH National Institute on Aging (NIA). NIA scientists and other experts review this content to ensure it is accurate and up to date.

An official website of the National Institutes of Health