New Test Aids in Diagnosis of Alzheimer’s

Treatment of Alzheimer’s disease is a significant challenge for the medical profession, a challenge that will continue to increase as baby boomers age. But before Alzheimer’s can be treated, it must be accurately diagnosed—a challenge in itself.

Now, a radiopharmaceutical compound that was approved earlier this year by the U.S. Food and Drug Administration is enabling clinicians to make such a diagnosis with better accuracy, leading to earlier treatment and more informed counseling options for patients and their families. The test is offered at UC Health University Hospital’s nuclear medicine department, which is fully accredited by the American College of Radiology.

Amyvid, a radioactive dye manufactured by Avid Radiophramaceuticals, owned by Eli Lilly and Co., was approved by the FDA in April. The dye is injected intravenously in a procedure that takes about an hour, counting time spent waiting for the dye to reach the brain and time the patient spends on the examination table during the scan.

“This test will allow us better accuracy in terms of our diagnosis in patients with whom a diagnosis is uncertain,” says UC Health neurologist Brendan Kelley, MD, Sandy and Bob Heimann Chair in Research and Education of Alzheimer’s in the University of Cincinnati (UC) College of Medicine’s neurology department and director of the Memory Disorders Center at the UC Gardner Neuroscience Institute, a center of excellence within UC Health.

“Having a test where we can be more certain of the diagnosis will provide a huge advantage when discussing medication options, prognosis and treatment decisions relevant to a person’s cognitive decline.”

Alzheimer’s disease is a disease of the brain characterized in its early stages by memory loss and progressing to marked memory loss and a decrease in thinking ability such as decision making and ability to perform activities of daily living.

According to the Centers for Disease Control and Prevention (CDC), as many as 5 million Americans have Alzheimer’s disease. The disease usually begins after age 60, and risk goes up with age, the CDC says—a focus of concern with the aging of the U.S. population.

There is no current known cure for Alzheimer’s, but medicines exist that have been shown to improve quality for life for Alzheimer’s patients or help control behavioral symptoms such as sleeplessness, anxiety and depression.

The active substance of Amyvid is florbetapir, an imaging agent that is administered via intravenous solution to produce positron emission tomography (PET) imaging of the brain. Florbetapir binds to a ligand that tags amyloid neuritic plaque density, considered a marker for Alzheimer’s, producing images of plaques viewable for diagnostic purposes.

“A positive scan would correlate with frequent or moderate plaques,” says Kelley, “so a positive scan in a person with dementia would be consistent with that dementia due to Alzheimer’s.” (The test also may be positive in patients with other types of neurological conditions as well as older people with normal condition, the FDA says.)

“A negative scan—few or no plaques—would indicate that the dementia is unlikely to be related to Alzheimer’s.”

Previously, Kelley says, neuropathological confirmation of a diagnosis of Alzheimer’s would either require a brain biopsy (performed in very rare cases to evaluate the cause of a person’s dementia) or examination of the brain after death (at autopsy).

“By being able to make a diagnosis of Alzheimer’s with increased confidence,” Kelley says, “we would be able to use the medicines currently approved by the FDA to treat that. And where the dementia is not caused by Alzheimer’s, we would be able to avoid putting a person on a medicine unnecessarily.”

According to the FDA, common adverse reactions to the test include headache, musculoskeletal pain, fatigue and nausea. Safety risks, as with all PET scans, include radiation risk and risks associated with image misinterpretation, the FDA says.

Amyvid scans—costing several thousand dollars—are not currently covered by Medicare and Medicaid, and private insurers tend to follow the government’s lead. The Centers for Medicare and Medicaid Services, the federal agency that administers Medicare and Medicaid, is evaluating the issue, with a decision expected sometime in 2013.

“At the present time, we plan to recommend the test only in patients where it can help us answer some diagnostic questions where other testing avenues have not provided clear information,” says Kelley. “The initial role I see in my practice is going to be with patients where a diagnosis is uncertain or for patients who have clinically atypical features, such as a patient who has moderately severe dementia, who is only 48 years old with no family history. Establishing a clearer diagnosis in that patient is going to have counseling impact on what I will say to their spouse and perhaps to their children.

“As we move forward and develop new therapies and medications to treat Alzheimer’s, I expect it will have a wider use in patients with dementia.”

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