How is Alzheimer’s disease diagnosed?

These tests are used to diagnose Alzheimer’s disease or to rule out other medical conditions that cause symptoms similar to Alzheimer’s disease:

  • Medical history. The physician will ask about current and past medical conditions, medications the patient is taking, and family history of Alzheimer’s disease or other memory disorders. He or she will also check all current vital signs (blood pressure, heart rate, temperature, pulse rate) and conduct a neurologic exam (check reflexes and coordination, eye movement, speech and sensation).
  • Blood and urine tests. These are standard lab tests conducted to rule out other causes of symptoms including blood counts, vitamin levels, liver and kidney function, mineral balance, and thyroid gland function tests.
  • Mental status testing. These tests include tests of memory, problem solving, focus, counting, and language skills. This type of testing can also monitor the progress of Alzheimer’s disease.
  • Neuropsychological testing. This exam includes tests to assess attention, memory, language, the ability to plan and reason, the ability to change behavior, as well as personality and emotional stability. This type of testing can also monitor the progress of Alzheimer’s disease.
  • Spinal tap. Also called a lumbar puncture, this test checks for the tau and amyloid proteins that form the plaques and tangles seen in the brains of people with Alzheimer’s disease.
  • Brain imaging tests:
    • Computed tomography (CT). This scan reveals physical changes in the structure of brain tissue seen in the later changes of Alzheimer’s disease, including decrease in the size of the brain (atrophy), widening of the indentations of the brain tissues, and enlargement of the fluid-filled chambers of the brain.
    • Magnetic resonance imaging. This scan can also show brain atrophy. In addition, it can identify strokes, tumors, the buildup of fluid on the brain, and other structural damage that can cause symptoms similar to Alzheimer’s disease.
      • fMRI (functional MRI). This is a type of MRI that measures brain activity in a select area by detecting changes in blood flow. This test is being used by researchers to see how the brain changes at different stages of Alzheimer’s disease. It is also being used to evaluate treatments for Alzheimer’s disease before a person has symptoms.
    • Positron emission tomography. This scan shows the abnormal brain activity in a person affected by Alzheimer’s disease. It can also help diagnosis Alzheimer’s disease versus other forms of dementia.
      • Amyloid PET. This scan shows the buildup of amyloid protein in the brain.
      • FDG PET. This scans shows how well brain cells use glucose. A decline in the absorption of glucose is a sign of Alzheimer’s disease.

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