Alzheimer's Disease: Diagnosis
Details on tests doctors use to make a diagnosis of Alzheimer's disease.
There is no definitive test for Alzheimer's disease, and a true diagnosis of Alzheimer's can only be made after a person dies and an autopsy is performed on the brain. All individuals with Alzheimer's have an accumulation of abnormal deposits (called plaque) and tangled nerve cells in their brains. The physician will try to narrow down a diagnosis, however, by eliminating the possibility of other illnesses. He or she will ask the individual (or a close family member) to describe the primary symptoms, and how long they have been noticeable.
The following tests may also be used to aid in the diagnosis of Alzheimer's.
- Psychological tests - assess the individual's memory and attention span. They may also reveal difficulties in problem-solving, social, and language skills.
- Electroencephalograph (EEG)—traces brain-wave activity. This test sometimes reveals "slow waves" in people with AD. Although other diseases may reveal similar brain-wave activity, EEGs help distinguish a person with AD from a severely depressed person, whose brain waves are normal.
- Imaging tests (such as CT, MRI, or PET)—computerized tomography (CT) or magnetic resonance imaging (MRI) can detect the presence of stroke, blood clots, and tumors (problems that cause AD-like symptoms but are not themselves related to AD). MRI, positron emission tomography (PET) scans, and other advanced imaging techniques may eventually be able to diagnose AD by identifying altered blood flow patterns in the brain.
- Blood test for Apo E4—although the presence of Apo E4 gene in the blood may suggest AD, it does not always make an accurate diagnosis.