Diagnosis

Electroencephalography

Electroencephalography (EEG) traces brain-wave activity; in some patients with Alzheimer's disease this test reveals "slow waves." Although other diseases may evidence similar abnormalities, EEG data helps distinguish a potential patient with Alzheimer's disease from patient with severe depression, whose brain waves are normal.

Imaging Tests

Imaging tests include magnetic resonance imaging (MRI), positron-emission tomography (PET), and single photon emission computed tomography (SPECT). These tests are sometimes used to rule out other disorders such as multi-infarct dementia, stroke, blood clots, and tumors. Research is being conducted to determine if these tests can help to confirm a diagnosis of Alzheimer's disease and improve understanding of disease progression.

Click the icon to see an image of a MRI of the brain.

In 2005, the National Institute of Aging, in collaboration with industry partners, launched the $60 million Alzheimer's Disease Neuroimaging Initiative (ADNI). This landmark 5-year clinical trial, which will be conducted at 50 sites throughout the United States and Canada, will investigate whether neuroimaging techniques, such as MRI and PET scans, can be combined with biomarkers and neuropsychological tests to measure the progression of AD and mild cognitive impairment. In 2004, the U.S. Medicare system expanded insurance coverage of PET scans for eligible beneficiaries who meet specific diagnostic criteria for both Alzheimer's disease and fronto-temporal dementia. Medicare also covers the costs for patients enrolled in its agency-approved imaging clinical trials.

Research continues on Pittsburgh compound B, a tracer molecule used in PET brain scans to highlight beta-amyloid protein deposits. Results from this research may help to define potential drug targets and aid in the development of new Alzheimer's drugs.

Investigative Tests.

Blood Tests. Blood tests are currently used to check for anemia and other disorders that can produce dementia symptoms. Investigators are researching serum biomarkers, such as the iron transport protein p97, that might help detect the presence of Alzheimer's disease.

Cerebrospinal Fluid Test. Scientists are developing new nanotechnology screening methods that may eventually be used to identify Alzheimer's disease while it is still in its earliest stages and before plaque deposits accumulate. In 2005, a research team announced it had used a bio-barcode assay to detect tiny amounts of a protein called amyloid-beta-derived diffusable ligand (ADDL) in cerebrospinal fluid. ADDLs may be involved in cognitive decline and are a potential biomarker for early stage Alzheimer's disease. Tests for other proteins are also being developed.