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How is Alzheimer's Disease Diagnosed?

March 17, 2020

Editorial Review Phoebe Stoye, A.B. in Neurobiology, Harvard College
Clinical Review Benedict Albensi, PhD, BCMAS, CRQM
St Boniface Hospital Research Center

Alzheimer's is one of the four types of conditions that fall under the dementia umbrella. Most people tend to generalize and refer to all types of memory loss as Alzheimer's. This is not the case—the main difference between Alzheimer's and the other three types of dementia (vascular, Lewy body and frontotemporal) is that it has no identifiable underlying cause.

Signs, Symptoms, and Phases of Alzheimer's Disease

Alzheimer's is known as a "disease of exclusion," meaning labs and imaging studies are performed, yet the diagnosis is not made until all other potential causes of the symptoms are ruled out. This makes Alzheimer's different from the other forms of dementia. Therefore, a patient cannot be diagnosed with Alzheimer's if they have had a medical condition—such as a stroke or Parkinson's Disease—that could explain their symptoms.

Symptoms of Alzheimer's develop gradually and over time, in stages. Patients with Alzheimer's are typically older (>65 years old), have memory issues, see declines in judgment and problem solving abilities, and experience behavioral issues that may include changes in personality. Family and friends may notice the person has difficulty remembering simple things, and often lose items. They may frequently ask questions over and over, and become more irritable or frustrated due to their symptoms. Generally, clinicians categorize Alzheimer's Disease into early, early to moderate, moderate, moderate to severe, or severe stages.

Editor's Note: If you think you or your loved one may have Alzheimer's Disease, use Caretalk's tool to evaluate the stage of Alzheimer's Disease & appropriate treatments, created by clinicians.

Diagnosing Alzheimer's Disease

Typically, individuals are initially evaluated for Alzheimer's Disease when they or family members become concerned about new signs. The primary care physician may then perform a workup, or refer the patient to a neurologist who can further examine the patient.

There is no particular blood work that can be done to diagnose Alzheimer's. A cognitive exam is initially performed, which includes a detailed list of questions and activities the patient is asked to complete in order to assess their understanding, reasoning, and comprehension. If the patient's score is concerning, further imaging studies are obtained. An MRI (magnetic resonance imaging) of the brain is the next step, which involves a radiographic test that requires a person to lay flat in a cylindrical machine while detailed pictures of their brain are taken. MRIs are a very useful tool to diagnose diseases in the brain. The patient may be told that their brain has white matter lesions or atrophy, meaning that certain areas of their brain has decreased in volume. Once the MRI has been completed, and if no other causes of the patient's symptoms could be determined, the doctor will diagnose the patient with Alzheimer's.

Alzheimer's is not easy to diagnose. There are multiple steps that need to be taken before a true diagnosis can be made. The first step is to speak with your primary care physician to discuss symptoms and how to proceed.

Editor's Note: Alzheimer's Disease is difficult to diagnose, and this has been a recent topic of research. If you want to learn about the latest research on diagnosing Alzheimer's, check out Caretalk's page on this topic.


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