There is no single test that proves a person has Alzheimer's. A diagnosis is made through a complete assessment consisting of six general parts that considers all possible causes.
- Medical History
- Phycial Exam
- Neurological Exam
- Mental Status Tests
- Brain Imaging
- Genetic Testing
During the medical workup, your health care provider will review your medical history. He or she will want to know about any current and past illnesses, as well as any medications you are taking. The doctor will also ask about key medical conditions affecting other family members, including whether they may have had Alzheimer's disease or related dementias.
Physical Exam And Diagnostic Tests
During a medical workup, you can expect the physician to:
- Ask about your diet, nutrition and use of drugs and alcohol.
- Review all your medications. (Bring a list or the containers of all medicines currently being taken, including over-the-counter drugs and supplements.)
- Check your blood pressure, temperature and pulse.
- Listen to your heart and lungs.
- Perform other procedures to assess overall health.
- Collect blood or urine samples for laboratory testing.
Information from a physical exam and laboratory tests can help identify health issues that can cause symptoms of dementia. Conditions other than Alzheimer's that may cause confused thinking, trouble focusing or memory problems include anemia, depression, infection, diabetes, kidney disease, liver disease, certain vitamin deficiencies, thyroid abnormalities, and problems with the heart, blood vessels and lungs.
During a neurological exam, the physician will closely evaluate the person for problems that may signal brain disorders other than Alzheimer's.The doctor will look for signs of small or large strokes, Parkinson's disease, brain tumors, fluid accumulation on the brain, and other illnesses that may impair memory or thinking.
The physician will test:
- Coordination, muscle tone and strength
- Eye movement
The neurological exam may also include a brain imaging study. If the evaluation does not indicate Alzheimer's disease or a related dementia, but the symptoms continue to get worse over time, your doctor may need to order more tests or you may wish to get a second opinion.
Mental Status Tests
Mental status testing evaluates memory, problem-solving abilities and other thinking skills. Such tests give an overall sense of whether a person:
- Is aware of their symptoms
- Knows the date and time
- Knows where he or she is
- Can remember a short list of words, follow instructions and do simple calculations
The mini-mental state exam and the mini-cog test are two commonly used tests.
Mini-Mental State Exam (MMSE)
During the MMSE, a health professional asks a patient a series of questions designed to test a range of everyday mental skills.
The maximum MMSE score is 30 points. A score of 20 to 24 suggests mild dementia, 13 to 20 suggests moderate dementia, and less than 12 indicates severe dementia. On average, the MMSE score of a person with Alzheimer's declines about two to four points each year.
During the mini-cog, a person is asked to complete two tasks:
- Remember the names of three common objects and repeat them a few minutes later.
- Draw a face of a clock showing all 12 numbers in the right places and a time specified by the examiner.
The results of this brief test can help a physician determine if further evaluation is needed.
In addition to assessing mental status, the doctor will evaluate a person's sense of well-being to detect depression or other mood disorders that can cause memory problems, loss of interest in life, and other symptoms that can overlap with dementia.
Brain Imaging Tests
A standard medical workup for Alzheimer's disease often includes structural imaging with MRI or CT scans. These tests are primarily used to rule out other conditions that may cause symptoms similar to Alzheimer's but require different treatment. Structural imaging can reveal tumors, evidence of small or large strokes, damage from severe head trauma or a buildup of fluid in the brain.
Imaging technologies have revolutionized our understanding of the structure and function of the living brain. Researchers are exploring whether the use of brain imaging may be expanded to play a more direct role in diagnosing Alzheimer's and detecting the disease early on.
Researchers have identified certain genes that increase the risk of developing Alzheimer's and other rare "deterministic" genes that directly cause Alzheimer's. Although genetic tests are available for some of these genes, health professionals do not currently recommend routine genetic testing for Alzheimer's disease.
While there is a blood test for APOE-e4, the strongest risk gene for Alzheimer's, this test is mainly used in clinical trials to identify people at higher risk of developing Alzheimer's. Carrying this gene mutation only indicates a greater risk; it does not indicate whether a person will develop Alzheimer's or whether a person has Alzheimer's. Genetic testing for APOE-e4 is controversial and should only be undertaken after discussion with a physician or genetic counselor.
Deterministic genes: Testing also is available for genes that cause autosomal dominant Alzheimer's disease (ADAD) or "familial Alzheimer's," a rare form of Alzheimer's that accounts for less than 5 percent of all cases. ADAD runs strongly in families and tends to begin earlier in life. Many people in these families do not wish to know their genetic status, but some get tested to learn whether they will eventually develop the disease. Some ADAD families have joined clinical studies to help researchers better understand Alzheimer's.
A Note on Home Screening Tests for Dementia
A number of dementia screening tests have been marketed directly to consumers. The Alzheimer's Association believes that home screening tests cannot and should not be used as a substitute for a thorough examination by a skilled doctor. The whole process of assessment and diagnosis should be carried out within the context of an ongoing relationship with a responsible health care professional.
Reproduced with permission from the Alzheimer's Association. © 2012 Alzheimer's Association.