Alzheimer's Disease Diagnosis

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

Still, AD diagnosis is not an exact science. The reason: there are various conditions that show similar symptoms to AD. And while genetics play a role in AD, approximately 75 percent of those with AD have no known family history of the condition. Thus, it is essential you consult with a doctor experienced in AD diagnostics.

Diagnostic Steps

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 hers 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 (such as blood, urine tests, and possibly spinal fluid) to help eliminate and/or identify additional health problems, such as diabetes, or 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: 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 lets a doctor see levels of brain activity from the use of glucose in specific areas of the brain.

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 , measurable changes in biomarkers, such as brain imaging and spinal fluid chemistry. Currently, there are no clinical diagnostic criteria for this phase. However, 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. These can be noticed and measured, but not to the extent it affects 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.