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How Is Alzheimer’s Disease Diagnosed?

While some degree of memory loss or cognitive impairment is common as you get older, Alzheimer’s disease is not. An accurate diagnosis of Alzheimer’s disease is crucial for appropriate treatment and care, as well as long-term plans. There are multiple aspects of the diagnosis process for Alzheimer’s disease; this helps rule out other possible causes of the reported symptoms, since other medical conditions can cause symptoms similar to those of Alzheimer’s. In this way, doctors are able to differentiate between possible Alzheimer’s disease and probable Alzheimer’s disease.

A definitive diagnosis of Alzheimer’s disease can only be done post-mortem, or after death.1 This is because the brain tissue needs to be examined upon autopsy for the changes the disease causes.

Medical history

If you’re experiencing cognitive symptoms or memory issues, you can see your general practitioner, a neurologist (a doctor who specializes in brain disorders or conditions), or a geriatrician. They will ask you about your medical history, whether you have any existing medical conditions, and what symptoms you are having and how it’s affected your life. They will likely do a physical examination to see if there is a medical condition that could be causing your symptoms, like an infection, medication side effects, sleep disorders, Parkinson’s, or possible stroke.1,2 If you first see your general practitioner, they might send you to a specialist for more detailed testing.

Testing for Alzheimer’s

In addition to a physical exam, specialists may conduct other tests such as mental status testing, neuropsychological testing, and talk with friends and family. These tests help provide them with a broader picture of your mental status and any personality or behavior changes you might not be aware of that are pertinent to a diagnosis. Laboratory tests might be done to rule out things like a thyroid disorder or vitamin B-12 deficiency, both of which can cause symptoms similar to Alzheimer’s disease.2

One of the main effects of Alzheimer’s disease is the destruction of brain cells, which can show up on brain imaging tests. Various imaging tests may be done not only to see if these changes are apparent on the scan, but also to rule out other neurological issues like a tumor, normal age-related brain changes, possible hemorrhage, or any other brain disease. Brain imaging tests that may be done can include MRI (magnetic resonance imaging), a CT scan (computerized tomography), or a PET scan (positron emission tomography).2 Brain scans alone aren’t enough to make a diagnosis of probable Alzheimer’s disease, though, because many age-related changes in the brain can overlap with abnormal changes, and the scans alone are not a definitive diagnostic tool.2 While helpful, these can be more helpful in ruling out other potential disorders.

Considerations during the diagnosis journey

Getting an accurate diagnosis of Alzheimer’s can be beneficial not only for treatment purposes but also to put you at ease. Not knowing why you’re suddenly having memory lapses or cognitive issues can be scary and stressful, and a diagnosis helps give you a plan and resources. It also helps connect you with professionals and potentially, other patients living with the disease so you can get support and learn from each other. It also provides you and your family or caregivers with the necessary information to learn about the course of the disease and plan for the future. You might also be able to take part in any clinical trials or research studies.

Written by: Jaime Rochelle Herndon | Last reviewed: June 2019
  1. National Institute on Aging. How is Alzheimer’s Disease Diagnosed? 2017. https://www.nia.nih.gov/health/how-alzheimers-disease-diagnosed Accessed March 18, 2019.
  2. Mayo Clinic. Diagnosing Alzheimer’s: How Alzheimer’s is Diagnosed. 2016. https://www.mayoclinic.org/diseases-conditions/alzheimers-disease/in-depth/alzheimers/art-20048075 Accessed March 18, 2019.