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Northwestern University Feinberg School of Medicine
Mesulam Center for Cognitive Neurology and Alzheimer’s Disease
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Diagnosis of Alzheimer's Disease

The absolute diagnosis of Alzheimer's disease (AD) is made on the basis of a brain autopsy. However, physicians at specialized centers can diagnose AD with great certainty based on the clinical examination of the affected individual.

To make the diagnosis, the following may be conducted:

  • A medical history and neurological exam
  • Neuropsychological testing (specialized tests of a person's short-term memory, problem-solving, language, attention and visuospatial abilities) for comparison with standards for individuals of the same age and with the same level of education
  • Blood tests to help exclude other possible causes of memory change (for example, a person with a thyroid disorder or a vitamin deficiency may have problems with his or her memory that are potential reversible with adequate treatment)
  • A brain scan such as an MRI or a CT scan to detect other possible causes of cognitive decline such as brain tumors, strokes or other brain abnormalities that may cause memory problems; the MRI or CT scan cannot show the changes of AD, which are only seen under a microscope
  • We now have a lumbar puncture (or spinal tap) test that can help detect the buildup of proteins (amyloid and tau) of AD, which can reliably predict whether AD is present in the brain and therefore the likely cause of the dementia
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