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VNA of Care New England

Diagnosis of Alzheimers Disease

Diagnostic Tests

Your doctor will ask about your symptoms and medical history. A physical exam will be done. Your doctor will make a diagnosis of Alzheimers after a thorough clinical evaluation and a series of tests. Other tests may include those which will increase or decrease the likelihood that you have Alzheimers disease. Your doctor will also perform tests to eliminate the possibility of other conditions causing the dementia.

Tests to Assess Dementia

These tests help determine if you have signs of dementia, how severe the dementia is, or to look for other causes of dementia. They may include:
  • Neurological exam—examines the nervous system for evidence of other neurological disorders. This may include mental status testing of:
    • Memory
    • Sense of time and place
    • Problem-solving abilities
    • Attention span
    • Language skills
    • Visual-spatial perception
    • Learning capacity
    • Judgement
    • Decision-making skills
  • Psychological evaluation—looks for depression or other emotional illnesses that may be the first sign of Alzheimers disease
  • MRI scan , CT scan , and/or PET/CT scan —take detailed pictures of your brain to identify any abnormalities
  • Lumbar puncture —tests the fluid surrounding the brain and spinal cord to look for infections that can cause dementia, or show markers of Alzheimers, such as beta amyloid and tau proteins
Additionally, electroencephalogram (EEG) is a test that evaluates and follows the electrical activity of the brain. It is not a common test for evaluating most dementias, but it may be done.

Blood and Urine Tests

Blood and urine tests may be ordered to look for other conditions that cause dementia. The tests may include:
  • Electrolytes
  • Thyroid function tests
  • Complete blood count (CBC)
  • Levels of vitamins (including B vitamins)
  • Erythrocyte sedimentation rate (ESR)
  • Lyme disease test
  • HIV test
  • Vasculitis work up

Genetic Tests

Genetic tests can look for markers that increase your risk for early-onset Alzheimers. Your doctor may recommend this test if you have family members with this condition.

Diagnostic Categories

An Alzheimers disease diagnosis usually falls into one of three categories:
  • Probable Alzheimers disease—This indicates that other dementia-related disorders have likely been ruled out. The symptoms are most likely due to Alzheimers disease. At least two areas of cognition are affected. One area is a worsening of memory.
  • Possible Alzheimers disease—The dementia is possibly caused by Alzheimers disease. There may be other disorders that are causing the dementia.
  • Definite Alzheimers disease—This diagnosis can only be made at the time of death. It is done through an autopsy when the brain tissue can be examined. This is the only way to diagnose the disease with complete certainty.

References

Alzheimers disease. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed.ebscohost.com/about/about-us. Updated August 19, 2013. Accessed September 5, 2013.

Alzheimer's disease medications fact sheet. National Institute on Aging website. Available at: http://www.nia.nih.gov/Alzheimers/Publications/medicationsfs.htm. Updated July 2010. Accessed September 5, 2013.

Bombois S, Duhamel A, et al. A new decision tree combining Abeta 1-42 and p-Tau levels in Alzheimer’s diagnosis. Curr Alzheimer Res. 2013;10(4):357-64.

Frisoni GB, Bocchetta M, et al. Imaging markers for Alzheimer disease: Which vs how. Neurology. 2013;81(5):487-500.

Ghidoni R, Benussi L, et al. Cerebrospinal fluid biomarkers in Alzheimer’s disease: the present and the future. Neurodegen Dis. 2011;8:413-420.

Hampel H, Frank R, et al. Biomarkers for Alzheimer’s disease: academic, industry and regulatory perspectives. Nat Rev Drug Discov. 2010;9(7):560-574.

Riverol M, Lopez OL. Biomarkers in Alzheimer’s disease. Front Neurol. 2011;2:46.

What is Alzheimer's? Alzheimer’s Association website. Available at: http://www.alz.org/alzheimers%5Fdisease%5Fwhat%5Fis%5Falzheimers.asp. Accessed September 5, 2013.

9/3/2014 DynaMed's Systematic Literature Surveillance. Available at: http://www.ebscohost.com/dynamed: Wippold FJ, Cornelius RS, et al. American College of Radiology (ACR) Appropriateness Criteria for dementia and movement disorders. Available at: http://www.acr.org/~/media/ACR/Documents/AppCriteria/Diagnostic/DementiaAndMovementDisorders.pdf. Updated 2014. Accessed September 3, 2014.

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