Alzheimer's Disease Diagnosis

Written by Wendy Leonard, MPH | Published on August 29, 2014
Medically Reviewed by Brenda B. Spriggs, MD, MPH, MBA on August 29, 2014

Alzheimer's Disease Diagnosis

In the past, Alzheimer’s disease (AD) was only confirmed after a person had died and an autopsy was performed on the brain. Today, physicians are able to make an accurate diagnosis in a living person. 

Still, the diagnosis of AD is not an exact science. There are various conditions that show similar symptoms to AD. And while genetics play a role, approximately 75 percent of individuals  with AD have no known family history of the condition. It’s essential that you consult with a doctor experienced in diagnosing Alzheimer’s disease.

DiagnosticSteps

An experienced AD doctor will take the following steps.

Patient History

A detailed patient history will be conducted, including: 

  • description of how and when symptoms developed
  • description of the person’s overall medical condition and history
  • description of the family’s overall medical condition and history
  • assessment of the person’s emotional state and living environment

Also, the doctor may speak with the patient’s friends and family. They can offer insight into his or her personality, behavior, memory, and cognitive skills.

Physical Examination and Lab Tests

A comprehensive physical exam will be conducted, including: 

  • an evaluation of the patient’s hearing, sight, heart, lungs, temperature, blood pressure, and pulse readings
  • lab tests ( blood, urine, and possibly spinal fluid examination) may be performed to help eliminate or identify additional health problems, such as diabetes, thyroid, or liver problems

Neuropsychological Testing

The most common neuropsychological test is the Mini-Mental State Exam (MMSE). The MMSE includes a selection of questions and tasks designed to evaluate a patient’s basic cognitive (mental) status. Examples include questions such as: do they know today’s date and where they are? can they repeat a list of words or a phrases? can they count backwards from 100 by sevens? This test is not perfect. For example, the results can be affected by a person’s level of education. Yet it is a good starting point for assessing AD.

Brain Imaging

  • MRI (magnetic resonance imaging) and CT (computed tomography) scans: These diagnostic tools can rule out other reasons for AD symptoms, such as brain tumors or blood clots.
  • PET (positron emission tomography) scan: This allows a doctor to see areas and intensity  of metabolic activity in the brain, using radioactive glucose.

Genetic Testing

Diagnosing early-onset AD (when symptoms appear in a person well before the age of 60) will likely include genetic testing.

The Latest in AD Diagnostics Criteria

Diagnosing dementias and AD used to be straightforward. Family or friends would notice problems with a person’s ability to think, learn, and remember.

But our knowledge about dementias and AD has increased over the years. It is now believed AD creates changes in the brain years, and even decades, before symptoms show up. In response, the National Institute on Aging (NIA), the National Institutes of Health (NIH), and the Alzheimer’s Association have published the following three phases to better reflect AD progression over time.

Preclinical Alzheimer’s Disease

This involves changes that may indicate the earliest signs of AD. Examples include measurable changes in biomarkers, such as brain imaging and spinal fluid chemistry. Currently, there are no clinical diagnostic criteria for this phase. But an outline has been created to help define this AD stage.

Mild Cognitive Impairment (MCI) Due To Alzheimer’s Disease

This denotes mild changes in memory and thinking abilities that can be measured. These changes are noticeable, but they are not severe enough to affect a person’s ability to function independently and perform everyday activities.

Dementia Due To Alzheimer’s Disease

This denotes cognitive (e.g. memory and thinking) and behavioral symptoms that impair a person’s ability to function in daily life.  

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There’s no specific test that can definitively diagnose Alzheimer’s, but several exams such as the mini-cog, scans like MRIs, and molecular imaging can help.
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