Alzheimer's Disease Screening & Diagnosis
Screening and Testing for Alzheimer’s Disease
Although it can be difficult to diagnose Alzheimer’s disease, in an estimated 90 percent of cases, physicians can correctly diagnose the condition based on a:
- Recent history of mental and behavioral symptoms
- Physical exam and laboratory tests
- Neuropsychological test, if needed, to identify specific problems in mental function and behavior
Recent History of Symptoms
A physician will take a history of mental and behavioral symptoms, using information provided by the patient and the family. In about 3 out of 4 cases, Alzheimer’s starts with the inability to remember recent events and learn and retain new information. Early-stage patients experience memory problems that interfere with daily living and steadily worsen. Other early symptoms can include:
- Loss of energy and spontaneity
- Difficulty in:
- Following instructions
- Abstract thinking
- Managing money
- Finding the right words
For a full range of symptoms, see Signs and Symptoms of Alzheimer’s disease.
The physician may be able to distinguish Alzheimer’s disease from other types of dementia based in part on the problems exhibited and the speed with which the disease progresses.
Physical Exam and Lab Tests
The physician will perform a physical examination to help identify and rule out other potential causes of dementia. This would include a general physical, blood tests, and urinalysis.
A blood test helps measure:
- Thyroid function: A failure to produce sufficient thyroid hormones is common in the elderly and can cause dementia.
- Vitamin B12 deficiency: This condition can also cause dementia in older people.
Brain scans or other imaging of the brain may rule out other causes of dementia. MRI (magnetic resonance imaging) can identify conditions like:
- Blood accumulation on the brain surface
- Brain tumors
Scans may also show structural changes in the brain that are characteristic of Alzheimer’s disease. Your doctor may administer an electroencephalogram (EEG) to measure electrical activity in the brain. In some cases, the doctor may recommend a lumbar puncture to test spinal fluid.
These tests assist the physician in diagnosing Alzheimer’s by identifying behavioral and mental symptoms associated with brain injury or abnormal brain function. Your doctor will recommend specific tests depending on symptoms and how far the dementia has advanced. Usually, physicians start with a brief screening tool such as the Mini-Mental Status Examination (MMSE) to help confirm that the patient is experiencing problems with intellectual functions.
The MMSE includes tests of:
- Mathematical calculation
For patients with mild intellectual deficits, more tests may be needed to determine whether the patient is simply showing signs of advanced age or is developing Alzheimer’s disease. The patient may be referred to a neuropsychologist, who can administer a battery of tests to identify more specific problems.
Looking for More Affordable and Reliable Tests
Be sure to check with your doctor’s office on insurance coverage of tests, since some costly technologies do not yet qualify for insurance coverage. For example, a scan test known as brain amyloid β PET imaging has been denied coverage by the Centers for Medicare and Medicaid Services (CMS) for clinical use (with the exception of certain clinical trials). Such a scan can cost $3,000 or more. Since most private insurers follow CMS recommendations and many Alzheimer’s patients are on Medicare, this ruling impacts patients’ screening options, for now.
Additional studies are underway to determine the scan’s usefulness in diagnosing Alzheimer’s disease and other dementias. Many scientists are researching new ways to inexpensively and reliably diagnose Alzheimer’s disease earlier and more accurately. Efforts include:
- Creating sophisticated brain imaging systems to help measure the slightest changes in brain function or structure, to diagnose Alzheimer’s before any noticeable symptoms occur
- Examining the correlation between early brain damage and outward clinical signs
- Looking at changes in the blood and cerebrospinal fluid to track the progression of the disease
- Testing of personality changes and cognition, measured through memory and recall tests that might predict which individuals are at higher risk for the disease
When to See a Doctor
If you or a loved one is exhibiting symptoms that could potentially be a result of Alzheimer’s or other types of dementia, consult a physician as soon as possible. Since current medications work best in the early stages of the disease, early screening and diagnosis are important.
Once a patient receives a diagnosis of Alzheimer’s disease, the next step is to find out whether treatments are available.