I read about experimental tests for Alzheimer's disease that can detect early stages of the disease. Are these helpful?
Answer From Jonathan Graff-Radford, M.D.
Developing a treatment plan for any disease requires a clear diagnosis. New Alzheimer's tests might help with early detection of some aspects of the disease.
Research is ongoing to develop new tests and determine who might benefit from them. More testing is needed before they can become widely available.
Biomarker test. A biomarker is something that can be measured to indicate the presence of a disease. Two proteins, beta-amyloid and tau, which are found in the brains of people with Alzheimer's can be measured in the fluid that surrounds the brain and spinal cord (cerebrospinal fluid).
The fluid is examined for evidence of abnormal development of beta-amyloid proteins, which form plaques, and tau proteins, which form tangles. Both plaques and tangles are thought to contribute to the development of Alzheimer's disease.
These proteins can distinguish Alzheimer's disease from other causes of dementia and may help identify people with the disease process before they have significant mental decline. They can support a diagnosis of Alzheimer's, but are not yet used routinely for diagnosis.
Brain imaging (neuroimaging). Researchers are studying imaging techniques, such as MRI and positron emission tomography (PET) scans, used with radiotracers.
Radiotracers are charged particles that "light up" Alzheimer's-affected areas in images of the brain — for example, by attaching to proteins, amyloid and tau, associated with Alzheimer's disease. However, having amyloid plaques in the brain doesn't mean you have dementia. More study is needed.
- Cognitive assessment. Technology is also being used to develop software for computer-based assessments that detect cognitive changes and may be useful in the early diagnosis of Alzheimer's disease.
- Loss of odor identification tests. Some studies indicate that the ability to identify odors (olfactory impairment) declines with mild cognitive impairment and with progression from mild cognitive impairment to Alzheimer's disease. Olfactory impairment has been associated with other diseases such as Parkinson's disease, as well.
Early detection and diagnosis of Alzheimer's disease is an important goal. Early intervention with medications might slow disease progression and provide an opportunity to plan for the future.
Jonathan Graff-Radford, M.D.
April 20, 2019
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- Graff-Radford J (expert opinion). Mayo Clinic, Rochester, Minn. July 3, 2017.