Making the Diagnosis of Alzheimer's Disease
CT (computed tomography) scanning is a technique in which multiple X-rays of the body are taken from different angles in a very short period of time. These images are then fed into a computer, which creates a series of images that look like "slices" through the body. CT scans can show certain changes that are characteristic of Alzheimer's disease in its later stages. These changes include a reduction in the size of the brain, referred to as atrophy.
Magnetic Resonance Imaging (MRI)
Magnetic resonance imaging, usually called MRI, is a test that produces very clear pictures, or images, of the human body without using X-rays. Instead, MRI uses a large magnet, radio waves, and a computer to produce these images. MRI is beneficial in ruling out other causes of dementia, such as tumors or strokes. It also may help to show the structural and functional changes in the brain that are associated with Alzheimer's disease.
Positron Emission Tomography (PET)
According to guidelines from the Society of Nuclear Medicine and Molecular Imaging and the Alzheimer's Association, PET scans of the brain can help diagnose Alzheimer's disease in some people. PET technology creates images of beta amyloid plaque buildup in the brain, a key characteristic in Alzheimer's disease. According to the guidelines, the test may be appropriate for:
- Those who complain of persistent or progressive unexplained memory problems or confusion and who demonstrate impairments using standard tests of cognition and memory.
- Individuals meeting tests for possible Alzheimer's, but who have unusual symptoms.
- Individuals with progressive dementia and an early age of onset (before age 65).
Electroencephalography (EEG) is a medical technique that measures brain function by analyzing the electrical activity generated by the brain. This activity is measured through special electrodes applied to the scalp. EEG can be used repeatedly in adults and children with virtually no risks and is helpful in diagnosing seizures, which may be contributing to behavioral changes seen in the patient.
An electrocardiogram (ECG) is a recording of the heart's electrical activity. This activity is registered as a graph or series of wavy lines on a moving strip of paper. This gives the doctor important information about the heart. For example, it can show the heart's rate and rhythm. It also can help show decreased blood flow, enlargement of the heart, or the presence of damage due to a current or past heart attack. This test may be used by the doctor to help rule out other conditions that may be causing symptoms similar to those of Alzheimer's disease.