There is no single test that proves a person has Alzheimer's. A diagnosis is made through a complete assessment that considers all possible causes.
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.
During a medical workup, you can expect the physician to:
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, infection, diabetes, kidney disease, liver disease, certain vitamin deficiencies, thyroid abnormalities, and problems with the heart, blood vessels and lungs.
If the diagnosis is Alzheimer’s or another dementia, you are not alone. Join AlzConnected, our message boards and online social networking community, to ask questions and receive support.
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.
Risk genes: 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 1 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.
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:
The neurological exam may also include a brain imaging study.
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.
Mental status testing evaluates memory, ability to solve simple problems and other thinking skills. Such tests give an overall sense of whether a person:
- Is aware of symptoms
- Knows the date, time, and where he or she is
- Can remember a short list of words, follow instructions and do simple calculations
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.
- Remember and a few minutes later repeat the names of three common objects
- 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.
Computerized tests cleared by the FDA
A growing area of research is the development of devices to administer computer-based tests of thinking, learning and memory, called cognitive tests.
The U.S. Food and Drug Administration (FDA) has cleared several computerized cognitive testing devices for marketing. These are the Cantab Mobile, Cognigram, Cognivue, Cognision and Automated Neuropsychological Assessment Metrics (ANAM) devices.
Some physicians use computer-based tests such as these in addition to the MMSE and Mini-Cog. Computerized tests have several advantages, including giving tests exactly the same way each time. Using both clinical tests and computer-based tests can give physicians a clearer understanding of cognitive difficulties experienced by patients.
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.
A standard medical workup for Alzheimer's disease often includes structural imaging with MRI or CT; 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 studying other brain imaging techniques so they can better diagnose and track the progress of Alzheimer’s.