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When effective treatments for Alzheimer’s and related dementias become available, doctors will need reliable tests for early detection and diagnosis. To this end, NIH invests in the development of easier-to-use, less expensive testing methods. This investment led to significant advances in 2020, particularly in the further development of blood and imaging tests. For example:
- Since fall 2020, physicians in a clinical research practice can order blood tests for amyloid protein, a hallmark sign of Alzheimer’s, for any patients, even those who are not participating in a study.
- Advances were made in brain imaging, most notably, the FDA approval of the first PET scan product to detect tau tangles in the brain, another hallmark sign of Alzheimer’s.
However, the current ability to obtain a diagnostic test for Alzheimer’s and related dementias in a doctor’s office is still quite limited, and biomarker imaging and lab tests are mainly used today by researchers to study people who volunteer to take part in related studies. NIH continues to fund multiple studies to discover and validate additional testing options.
Researchers recently identified various proteins and other substances that have potential to be new biomarkers of Alzheimer’s and related dementias:
- Tau tangles: When tau tangles collect in the brain, various tau forms can also be found in the spinal fluid and blood. Two NIH-supported research teams devised and tested methods of measuring ptau217 in blood samples. Both teams reported that ptau217 was better than ptau181 at detecting signs of Alzheimer’s and that ptau217 had the potential to rival PET imaging and spinal fluid testing at Alzheimer’s detection. Researchers continue to further develop blood test methods that detect ptau217.
- Protein groups: Researchers supported by the NIH Accelerating Medicines Partnership® Program for Alzheimer’s Disease (AMP® AD) measured 3,500 proteins in spinal fluid and 12,000 proteins in brain samples from people with Alzheimer’s and from cognitively normal study participants. The research team identified groups of proteins associated with Alzheimer’s, findings that are significant toward the discovery of new fluid biomarkers for Alzheimer’s.
- Neurofilament light chain: A team of researchers funded in part by NIH found further evidence to support the development of a blood-based biomarker test for neurofilament light chain for the inherited form of Alzheimer’s.
More research is needed to better understand whether neurofilament light chain would be a useful biomarker for people with the more common form of Alzheimer’s disease, meaning the type that is not inherited.
- Lipids: A team of international researchers analyzed the entire set of lipids (fatty substances) in blood plasma samples from about 2,000 people, including participants in the NIA-supported Alzheimer’s Disease Neuroimaging Initiative. The team discovered that certain lipids are linked to Alzheimer’s, signifying that these substances have potential as fluid biomarkers.
Recent studies have also noted that people with Alzheimer’s may have changes with their eyes or vision and that they may experience sleep disturbances, which are two more avenues of study for biomarkers:
- Eyes and vision changes: Recent NIH-supported studies have suggested that retina changes and vision and pupil changes might serve as biomarkers of Alzheimer’s and related dementias.
- Sleep disturbance: Three recent studies explored the relationship between sleep deprivation and abnormal deposits of certain proteins, such as tau tangles and amyloid plaques.
One of the research teams suggested that measuring sleep activity with wearable devices may have potential as an easy and safe way to predict the abnormal accumulation of proteins in the brain before cognitive decline and other symptoms of brain disease develop.
Developing biomarkers for Parkinson’s disease dementia and dementia with Lewy bodies
Biomarker development goes beyond Alzheimer’s: Many NIH-supported projects are aimed at finding new biomarkers and developing diagnostic tests for Alzheimer’s-related dementias, such as Parkinson’s disease dementia and dementia with Lewy bodies.
For example, clumped forms of the alpha-synuclein protein are found in the brains of people with Parkinson’s disease and Lewy body dementias, and a test of spinal fluid can detect the protein.
- To develop a diagnostic that would be easier than the spinal fluid test, NIH-supported researchers are working on a skin test for this biomarker. The team reported that they detected deposits of the clumped protein in skin samples from people with Lewy body dementias but not in healthy people. The skin test results were comparable to spinal fluid tests for alpha-synuclein.
- To further our understanding of potential biomarkers for Parkinson’s and other Lewy body dementias, NIH has been supporting several projects and programs, including the Accelerating Medicines Partnership® Program for Parkinson’s Disease (AMP® PD).
- NIH released a new funding opportunity to support the identification of biomarkers for Lewy body dementia. The aim is research projects that will increase understanding of how clinical information from people with Lewy bodies corresponds with abnormal areas observed in brain tissue collected after death.
New initiative to address health disparities through biomarker research
To better understand the prevalence, progression, and clinical impact of Alzheimer’s among Mexican Americans, NIH awarded additional funding in 2020 for more PET scans and other biomarker measures to the ongoing Health and Aging Brain Among Latino Elders (HABLE) study.
The additional funding will support the Health and Aging Brain Among Latino Elders-Amyloid, Tau, and Neurodegeneration (HABLE-AT[N]) study, which enables researchers to collect amyloid and tau PET imaging and other biomarker measures.
The goal is to better understand health disparities of brain aging and Alzheimer’s between Mexican Americans and non-Latino whites. An additional benefit of HABLE and HABLE AT(N) will be the ability to better classify/categorize participants into groups by type of dementia and stage of the disease. This will help facilitate potential enrollment in future studies.
Creating a legacy through brain donation
To help encourage the public to take part in brain donation for ongoing research efforts, NIH developed and released a feature article and social media toolkit. These materials are designed to be shared broadly and to spark discussions about this important topic.
The article focuses on why brain donors are needed and explains the steps in developing a donation plan. The social media toolkit includes image cards, sample social media posts, a flyer, an infographic, and drop-in language for grantee and other newsletters.
Available in both English and Spanish, the toolkit is already being used by the NIA-supported Alzheimer’s Disease Research Centers and others to spread the word about the importance of brain donation.
These brain donation materials also explain how people can enroll to donate to the NIH NeuroBioBank, which is supported by several parts of NIH:
- Eunice Kennedy Shriver National Institute of Child Health and Human Development
- National Institute of Mental Health
- National Institute of Neurological Disorders and Stroke
- National Institute on Aging
- National Institute on Drug Abuse
Through its NeuroBioBank, NIH distributes thousands of samples of human brain tissue to the research community each year to help spur research progress in understanding dementia. Many more donors are needed, however, because progress in understanding dementia relies on donors who represent the diversity of the U.S. Learn more about the donation process.
Behavioral research and biomarkers
Researchers have begun to investigate the possible psychological effects on people who do not have symptoms of dementia but who are told they have a biological sign of Alzheimer’s.
Two independent teams of behavioral and social scientists recently reported that learning biomarker test results does not cause serious distress among Alzheimer’s research participants. However, further research with more diverse populations is needed to examine the short-term and lasting psychological effects. More research is also needed on how physicians can best communicate results to lessen the chance of serious distress.
Studies on other possible effects from biomarker tests in people without symptoms are also being conducted. In June 2021, the National Academies of Sciences, Engineering, and Medicine hosted an NIA-sponsored two-day workshop to advance additional dialogue around this issue, explore new ideas, and discuss possible solutions to challenges arising from the use of biomarker tests.