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University of California San Francisco Study Finds Both High and Low Levels of High-Density Lipoprotein Cholesterol Associated with Increased Dementia Risk

If validated, study findings may result in new biomarkers for clinical laboratory cholesterol tests and for diagnosing dementia

Researchers continue to find new associations between biomarkers commonly tested by clinical laboratories and certain health conditions and diseases. One recent example comes from research conducted by the University of California San Francisco. The UCSF study connected cholesterol biomarkers generally used for managing cardiovascular disease with an increased risk for dementia as well.

The researchers found that both high and low levels of high-density lipoprotein (HDL)—often referred to as “good” cholesterol—was associated with dementia in older adults, according to a news release from the American Academy of Neurology (AAN).

UCSF’s large, longitudinal study incorporated data from 184,367 people in the Kaiser Permanente Northern California health plan. How the findings may alter cholesterol biomarker use in future diagnostics has not been determined.

The researchers published their findings in the journal Neurology titled, “Low- and High-Density Lipoprotein Cholesterol and Dementia Risk over 17 Years of Follow-up among Members of Large Health Care Plan.”

Maria Glymour, ScD

“The elevation in dementia risk with both high and low levels of HDL cholesterol was unexpected, but these increases are small, and their clinical significance is uncertain,” said epidemiologist Maria Glymour, ScD (above), study author and Professor of Epidemiology and Biostatistics at UCSF School of Medicine, in a news release. This is another example of how researchers are associating common biomarkers tested regularly by clinical laboratories with additional health conditions and disease states. (Photo copyright: University of California San Francisco.)

HDL Levels Link to Dementia Risk

The UCSF researchers used cholesterol measurements and health behavior questions as they tracked Kaiser Permanente Northern California health plan members who were at least 55 years old between 2002 and 2007, and who did not have dementia at the time of the study’s launch.

The researchers then followed up with the study participants through December 2020 to find out if they had developed dementia, Medical News Today reported.

“Previous studies on this topic have been inconclusive, and this study is especially informative because of the large number of participants and long follow-up,” said epidemiologist Maria Glymour, ScD, study author and Professor of Epidemiology and Biostatistics at UCSF School of Medicine, in the AAN news release. “This information allowed us to study the links with dementia across the range of cholesterol levels and achieve precise estimates even for people with cholesterol levels that are quite high or quite low.” 

According to HealthDay, UCSF’s study findings included the following:

  • More than 25,000 people developed dementia over about nine years. They were divided into five groups.
  • 53.7 milligrams per deciliter (mg/dL) was the average HDL cholesterol level, amid an optimal range of above 40 mg/dL for men and above 50 mg/dL for women.
  • A 15% rate of dementia was found in participants with HDL of 65 mg/dL or above.
  • A 7% rate of dementia was found in participants with HDL of 11 mg/dL to 41 mg/dL.

“We found a U-shaped relationship between HDL and dementia risk, such that people with either lower or higher HDL had a slightly elevated risk of dementia,” Erin Ferguson, PhD student of Epidemiology at UCSF, the study’s lead study author, told Medical News Today.

What about LDL?

The UCSF researchers found no correlation between low-density lipoprotein (LDL)—often referred to as “bad” cholesterol”—and increased risk for dementia. But the risk did increase slightly when use of statin lipid-lowering medications were included in the analysis.

“Higher LDL was not associated with dementia risk overall, but statin use qualitatively modified the association. Higher LDL was associated with a slightly greater risk of Alzheimer’s disease-related dementia for statin users,” the researchers wrote in Neurology.

“We found no association between LDL cholesterol and dementia risk in the overall study cohort. Our results add to evidence that HDL cholesterol has similarly complex associations with dementia as with heart disease and cancer,” Glymour noted in the AAN news release.

Australian Study also Links High HDL to Dementia

A separate study from Monash University in Melbourne, Victoria, Australia, found that “abnormally high levels” of HDL was also associated with increased risk for dementia, according to a Monash news release.

The Monash study—which was part of the ASPREE (ASPpirin in Reducing Events in the Elderly) trial of people taking daily aspirin—involved 16,703 Australians and 2,411 Americans during the years 2010 to 2014. The researchers found:

  • 850 participants had developed dementia over about six years.
  • A 27% increased risk of dementia among people with HDL above 80 mg/dL and a 42% higher dementia risk for people 75 years and older with high HDL levels.

These findings, Newsweek pointed out, do not necessarily mean that high levels of HDL cause dementia. 

“There might be additional factors that affect both these findings, such as a genetic link that we are currently unaware of,” Andrew Doig, PhD, Professor, Division of Neuroscience at University of Manchester, told Newsweek. Doig was not involved in the in the Monash University research.

Follow-up research could explore the possibility of diagnosing dementia earlier using blood tests and new biomarkers, Newsweek noted.

The Australian researchers published their findings in The Lancet Regional Health-Western Pacific titled, “Association of Plasma High-Density Lipoprotein Cholesterol Level with Risk of Incident Dementia: A Cohort Study of Healthy Older Adults.”

Cholesterol Lab Test Results of Value to Clinical Labs

If further studies validate new biomarkers for testing and diagnosis, a medical laboratory’s longitudinal record of cholesterol test results over many years may be useful in identifying people with an increased risk for dementia.

Clinical pathologists and laboratory managers will want to stay tuned as additional study insights and findings are validated and published. Existing laboratory testing reference ranges may need to be revised as well.

As well, the findings of this UCSF research demonstrate that, in this age of information, there will be plenty of opportunities for clinical lab scientists and pathologists to take their labs’ patient data and combine it with other sets of data. Digital tools like artificial intelligence (AI) and machine learning would then be used to assess that large pool of data and produce clinically actionable insights. In turn, that positions labs to add more value and be paid for that value.

—Donna Marie Pocius

Related Information:

Both High and Low HDL Cholesterol Tied to Increased Risk of Dementia

Low-and High-Density Lipoprotein Cholesterol and Dementia Risk over 17 Years of Follow-up among Members of a Large Health Care Plan

Both High and Low HDL Cholesterol Tied to Slight Increase in Risk of Dementia

How HDL “Good” Cholesterol Might Raise Dementia Risk

HDL vs. LDL Cholesterol

How Levels of “Good” Cholesterol May Increase Dementia Risk

High Levels of “Good Cholesterol” May Be Associated with Dementia Risk, Study Shows

Association of Plasma High-Density Lipoprotein Cholesterol Level with Incident Dementia: A Cohort Study of Healthy Older Adults

Study Claims High Good Cholesterol Levels Linked to Greater Dementia Risk

Researchers at Stanford University Discover Gene Variant That Appears to Protect Individuals from Both Alzheimer’s and Parkinson’s Disease

Study findings may lead to new clinical laboratory tests, as well as vaccines and immunotherapies for neurodegenerative diseases

Research into the human genome continues to produce useful new insights. This time, a study led by researchers at Stanford University identified a genetic variation that is believed to help “slow or even stall” progression of neurodegenerative diseases, including Alzheimer’s and Parkinson’s, according to a press release. Because these genetic variations are common, it is likely that diagnostic tests can be developed for use by clinical laboratories.

Researchers at Stanford Medicine led the study which discovered that approximately one in five individuals carry the gene variant, a protective allele identified as DR4 (aka, HLA-DR4). It’s one of a large number of alleles found in a gene known as DRB1.

DRB1 is part of a family of genes collectively known as the human lymphocyte antigen complex or HLA. The HLA-DRB1 gene plays a crucial role in the ability of the immune system to see a cell’s inner contents.

The Stanford scientists published their findings in the journal PNAS titled, “Multiancestry Analysis of the HLA Locus in Alzheimer’s and Parkinson’s Diseases Uncovers a Shared Adaptive Immune Response Mediated by HLA-DRB1*04 Subtypes.” Approximately 160 researchers from roughly 25 countries contributed to the work. 

Emmanuel Mignot, MD, PhD

“In an earlier study, we’d found that carrying the DR4 allele seemed to protect against Parkinson’s disease,” said Emmanuel Mignot, MD, PhD (above), Director of the Stanford Center for Narcolepsy, in a Stanford press release. “Now, we’ve found a similar impact of DR4 on Alzheimer’s disease.” Clinical laboratories may soon have new vaccines for both neurodegenerative diseases. (Photo copyright: Stanford University.)


DR4 Found to Impact Both Parkinson’s and Alzheimer’s Diseases

To perform their research, the team examined a large collection of medical and genetic databases from 176,000 people who had either Alzheimer’s or Parkinson’s disease. The people involved in the study were from numerous countries located in East Asia, Europe, the Middle East and South America. Their genomes were then compared with people who did not have the diseases, focusing on the incidence and age of onset.

“In an earlier study we’d found that carrying the DR4 allele seemed to protect against Parkinson’s disease,” said Mignot in the Stanford press release. “Now, we’ve found a similar impact of DR4 on Alzheimer’s disease.”

The team found that about 20% to 30% of people carry DR4, and that they have around a 10% risk reduction for developing the two diseases. 

“That this protective factor for Parkinson’s wound up having the same protective effect with respect to Alzheimer’s floored me,” said Emmanuel Mignot, MD, PhD, the Craig Reynolds Professor of Sleep Medicine in the Department of Psychiatry and Behavioral Sciences at Stanford University and the Director of the Stanford Center for Narcolepsy, in the Stanford Medicine press release. “The night after we found that out, I couldn’t sleep.”

The scientists also analyzed data from autopsied brains of more than 7,000 Alzheimer’s patients and discovered that individuals who carry DR4 had fewer neurofibrillary tangles and that those tangles are composed mainly of modified tau proteins, a common biomarker for Alzheimer’s.

The presence of these tangles corresponds with the severity of Alzheimer’s disease. They are not typically seen in Parkinson’s patients, but the Stanford team found that Parkinson’s patients who did carry DR4 experienced later onset of symptoms.

Mignot stated that tau, which is essential in Alzheimer’s, may also play a role in Parkinson’s, but that further research is required to prove its function.

Both diseases are characterized by the progressive loss of certain nerve cells or neurons in the brain and are linked to an accumulation of abnormal proteins. The Stanford researchers suggested that the DR4 gene variant may help protect individuals from Alzheimer’s and Parkinson’s by preventing the buildup of tau proteins.

“This is a very interesting study, providing additional evidence of the involvement of the immune system in the pathogenesis of Alzheimer’s and Parkinson’s,” neurologist Wassim Elyaman, PhD, Assistant Professor of Neurological Sciences in Neurology, the Taub Institute and the Institute for Genomic Medicine at Columbia University, told Live Science.

New Vaccines and Immunotherapies

According to the Alzheimer’s Association, more than six million Americans are currently living with Alzheimer’s disease and approximately one in three Americans die with Alzheimer’s or another dementia. 

The Parkinson’s Foundation states that nearly one million Americans are currently living with Parkinson’s disease, and that number is expected to rise to 1.2 million by 2030. Parkinson’s is the second-most common neurodegenerative disease after Alzheimer’s disease.

Even though the genetic analysis of the Stanford research is strong, more immune cell and blood-based research is needed to definitively establish how tau is connected to the two diseases.

This research could have implications for clinical laboratories by giving them biomarkers for a useful new diagnostic test, particularly for diagnosing Alzheimer’s and Parkinson’s.

Further, Mignot suggested that an effective vaccine could delay the onset or slow the progression of both diseases. He hopes to test his hypothesis on genetically modified mice and eventually human subjects.

—JP Schlingman

Related Information:

Stanford Medicine-led Study Finds Genetic Factor Fends Off Alzheimer’s and Parkinson’s

Gene Variant Carried by One in Five People May Guard Against Alzheimer’s and Parkinson’s, Massive Study Finds

Multiancestry Analysis of the HLA Locus in Alzheimer’s and Parkinson’s Diseases Uncovers a Shared Adaptive Immune Response Mediated by HLA-DRB1*04 Subtypes

Alzheimer’s Disease: Tau Biology and Pathology

Tau Protein and Alzheimer’s Disease: What’s the Connection?

C₂N Diagnostics Releases PrecivityAD, the First Clinical Laboratory Blood Test for Alzheimer’s Disease

New Research Challenges Long-Held Theory about Causes of Alzheimer’s Disease, Creating the Possibility of Useful New Biomarkers for Clinical Laboratory Tests

University of Cincinnati researchers hypothesize that low levels of amyloid-beta protein, not amyloid plaques, are to blame

New research from the University of Cincinnati (UC) and Karolinska Institute in Sweden challenges the prevailing theory about the causes of Alzheimer’s disease, suggesting the possibility of new avenues for the development of effective clinical laboratory assays, as well as effective therapies for treating patients diagnosed with Alzheimer’s.

Scientists have long theorized that the disease is caused by a buildup of amyloid plaques in the brain. These plaques are hardened forms of the amyloid-beta protein, according to a UC news story.

However, in their findings published in the Journal of Alzheimer’s Disease, titled “High Soluble Amyloid-β42 Predicts Normal Cognition in Amyloid-Positive Individuals with Alzheimer’s Disease-Causing Mutations,” the researchers advanced an alternative hypothesis—that Alzheimer’s is instead caused by “depletion” of a soluble form of that same amyloid-beta protein.

“The paradox is that so many of us accrue plaques in our brains as we age, and yet so few of us with plaques go on to develop dementia,” said Alberto Espay, MD, one of the lead researchers of the study, in another UC news story. Espay is Professor of Neurology at the UC College of Medicine and Director and Endowed Chair of the Gardner Center for Parkinson’s Disease and Movement Disorders.

“Yet the plaques remain the center of our attention as it relates to biomarker development and therapeutic strategies,” he added.

Alberto Espay, MD

“It’s only too logical, if you are detached from the biases that we’ve created for too long, that a neurodegenerative process is caused by something we lose, amyloid-beta, rather than something we gain, amyloid plaques,” said Alberto Espay, MD (above), in a University of Cincinnati news story. “Degeneration is a process of loss, and what we lose turns out to be much more important.” The UC study could lead to new clinical laboratory diagnostics, as well as treatments for Alzheimer’s and Parkinson’s diseases. (Photo copyright: University of Cincinnati.)

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High Levels of Aβ42 Associated with Lower Dementia Risk

In their retrospective longitudinal study, the UC researchers looked at clinical assessments of individuals participating in the Dominantly Inherited Alzheimer Network (DIAN) cohort study. DIAN is an ongoing effort, sponsored by the Washington University School of Medicine in St. Louis, to identify biomarkers associated with Alzheimer’s among people who carry Alzheimer’s mutations.

The researchers found that study participants with high levels of a soluble amyloid-beta protein, Aβ42, were less likely to develop dementia than those with lower levels of the protein, regardless of the levels of amyloid plaques in their brains or the amount of tau protein—either as phosphorylated tau (p-tau) or total tau (t-tau)—in their cerebral spinal fluid. P-tau and t-tau are proteins that form “tau tangles” in the brain that are also associated with Alzheimer’s.

One limitation of the study was that the researchers were unable to include Aβ40, another amyloid-beta protein, in their analysis. But they noted that this “did not limit the testing of our hypothesis since Aβ40 exhibits lower fibrillogenicity and lesser depletion than Aβ42, and is therefore less relevant to the process of protein aggregation than Aβ42.” Fibrillogenicity, in this context, refers to the process by which the amyloid-beta protein hardens into plaque.

While the presence of plaques may be correlated with Alzheimer’s, “Espay and his colleagues hypothesized that plaques are simply a consequence of the levels of soluble amyloid-beta in the brain decreasing,” UC news stated. “These levels decrease because the normal protein, under situations of biological, metabolic, or infectious stress, transform into the abnormal amyloid plaques.”

The UC News story also noted that many attempts to develop therapeutics for Alzheimer’s have focused on reducing amyloid plaques, but “in some clinical trials that reduced the levels of soluble amyloid-beta, patients showed worsening in clinical outcomes.”

New Therapeutics for Multiple Neurodegenerative Diseases

Eisai, a Japanese pharmaceutical company, recently announced phase three clinical trial results of lecanemab, an experimental drug jointly developed by Eisai and Biogen, claiming that the experimental Alzheimer’s drug modestly reduced cognitive decline in early-stage patients, according to NBC News.

Espay noted that lecanemab “does something that most other anti-amyloid treatments don’t do in addition to reducing amyloid: it increases the levels of the soluble amyloid-beta.” That may slow the process of soluble proteins hardening into plaques.

Beyond their findings about Alzheimer’s, the researchers believe similar mechanisms could be at work in other neurodegenerative diseases such as Parkinson’s disease, where the soluble alpha-synuclein protein also hardens into deposits.

“We’re advocating that what may be more meaningful across all degenerative diseases is the loss of normal proteins rather than the measurable fraction of abnormal proteins,” Espay said. “The net effect is a loss not a gain of proteins as the brain continues to shrink as these diseases progress.”

Espay foresees two approaches to treating these diseases: Rescue medicine, perhaps based on increasing levels of important proteins, and precision medicine, which “entails going deeper to understand what is causing levels of soluble amyloid-beta to decrease in the first place, whether it is a virus, a toxin, a nanoparticle, or a biological or genetic process,” according to UC News. “If the root cause is addressed, the levels of the protein wouldn’t need to be boosted because there would be no transformation from soluble, normal proteins to amyloid plaques.”

Clinical Laboratory Impact

What does this mean for clinical laboratories engaged in treatment of both Alzheimer’s and Parkinson’s patients? A new understanding of the disease would create “the opportunity to identify new biomarkers and create new clinical laboratory tests that may help diagnose Alzheimer’s earlier in the disease progression, along with tests that help with the patient’s prognosis and monitoring his or her progression,” said Robert Michel, Editor-in-Chief of Dark Daily and its sister publication The Dark Report.

Given the incidence of Alzheimer’s disease in the population, any clinical laboratory test cleared by the FDA would be a frequently-ordered assay, Michel noted. It also would create the opportunity for pathologists and clinical laboratories to provide valuable interpretation about the test results to the ordering physicians.

Stephen Beale

Related Information:

High Soluble Amyloid-β42 Predicts Normal Cognition in Amyloid-Positive Individuals with Alzheimer’s Disease-Causing Mutations

UC Study: Decreased Proteins, Not Amyloid Plaques, Tied to Alzheimer’s Disease

US News: Scientists Propose New Mechanism Driving Alzheimer’s

Scientists Propose New Mechanism Driving Alzheimer’s Disease

Alzheimer’s: Lack of Beta-Amyloid, Not Plaque Buildup, May Be the Culprit

Better Cognitive Predictor in People at High Risk of Alzheimer’s Disease

UC Study: Researchers Question Prevailing Alzheimer’s Theory with New Discovery

ABPP Amyloid Plaques’ Role in Onset of Alzheimer’s Questioned by Cincinnati University: GlobalData Reveals That ABPP Targeted by a Tenth of All Alzheimer’s Drugs

Blots on a Field? A Neuroscience Image Sleuth Finds Signs of Fabrication in Scores of Alzheimer’s Articles, Threatening a Reigning Theory of the Disease

WVXU: Does a Key Alzheimer’s Study Contain Fabricated Images?

New Research Suggests Clinical Laboratory Blood Tests Could Fill A Void in Alzheimer’s Disease Diagnoses

Studies presented at the Alzheimer’s Association International Conference point to the p-tau217 protein as an especially useful biomarker

Researchers disclosed a potentially useful biomarker for Alzheimer’s Disease at a major conference this summer. The good news for clinical laboratories is that the biomarker is found in blood. If further research confirms these early findings, medical laboratories could one day have a diagnostic test for this condition.

That possibility emerged from the Alzheimer’s Association International Conference (AAIC), which was held online July 27-31. Researchers presented findings from multiple studies that suggested blood/plasma levels of a protein known as phospho-tau217 (p-tau217) can indicate brain anomalies associated with Alzheimer’s.“Changes in brain proteins amyloid and tau, and their formation into clumps known as plaques and tangles, respectively, are defining physical features of Alzheimer’s disease in the brain,” states an AAIC press release. “Buildup of tau tangles is thought to correlate closely with cognitive decline. In these newly reported results, blood/plasma levels of p-tau217, one of the forms of tau found in tangles, also seem to correlate closely with buildup of amyloid.”

At present, “there is no single diagnostic test that can determine if a person has Alzheimer’s disease,” the association states on its website. Clinicians will typically review a patient’s medical history and conduct tests to evaluate memory and other everyday thinking skills. That may help determine that an individual has dementia, but not necessarily that Alzheimer’s is the cause.

“Currently, the brain changes that occur before Alzheimer’s dementia symptoms appear can only be reliably assessed by positron-emission tomography (PET) scans, and from measuring amyloid and tau proteins in [cerebrospinal] fluid (CSF),” the association states. “These methods are expensive and invasive. And, too often, they are unavailable because they are not covered by insurance or difficult to access, or both.”

In the AAIC press release, Alzheimer’s Association Chief Science Officer Maria C. Carrillo, PhD, said that a clinical laboratory blood test “would fill an urgent need for simple, inexpensive, non-invasive and easily available diagnostic tools for Alzheimer’s.

“New testing technologies could also support drug development in many ways,” she added. “For example, by helping identify the right people for clinical trials, and by tracking the impact of therapies being tested. The possibility of early detection and being able to intervene with a treatment before significant damage to the brain from Alzheimer’s disease would be game changing for individuals, families, and our healthcare system.”

However, she cautioned, “these are early results, and we do not yet know how long it will be until these tests are available for clinical use. They need to be tested in long-term, large-scale studies, such as Alzheimer’s clinical trials.”

Eli Lilly Clinical Laboratory Alzheimer’s Test

In one study presented at the conference, titled, “Discriminative Accuracy of Plasma Phospho-tau217 for Alzheimer Disease vs Other Neurodegenerative Disorders,” researchers evaluated an experimental p-tau217 medical laboratory test developed by Eli Lilly. They published their research in JAMA Network.

The study, led by Oskar Hansson, MD, of Lund University in Sweden, included 1,402 participants. About half of these were enrolled in BioFINDER-2, an ongoing dementia study in Sweden. In this group, researchers were most interested in the test’s ability to distinguish Alzheimer’s from other neurodegenerative disorders that cause dementia.

Diagnostic accuracy was between 89% and 98%, the researchers reported, which was similar to the performance of PET imaging and CSF tests. P-tau217 was more accurate than magnetic resonance imaging (MRI) as well as other biomarkers, such as p-tau181.

Oskar-Hansson-PhD-Lund-University-400w@72ppi
“Today the majority of individuals with Alzheimer’s disease around the world do not get a timely diagnosis, which results in suboptimal symptomatic treatment and care,” Oskar Hansson, MD, said in an Eli Lilly news release. “With rising prevalence of Alzheimer’s disease, more patients will be evaluated in primary care and other clinics where CSF and PET biomarkers are not available. Blood-based biomarkers, like plasma p-tau217, together with digital tools for checking memory performance, such as smartphone-based apps, can considerably improve the diagnostic work-up of Alzheimer’s disease patients in such clinics.” (Photo copyright: Alzheimer’s Fund.)

Another cohort consisted of 81 participants in the Brain and Body Donation Program at Banner Sun Health Research Institute in Sun City, Ariz. In this program, elderly volunteers submit to periodic clinical assessments and agree to donate their organs and tissue for study after they die.

Here, the researchers’ primary goal was to determine the test’s ability to distinguish between individuals with and without Alzheimer’s. Researchers ran the p-tau217 test on plasma samples collected within 2.9 years of death and compared the results to postmortem examinations of the brain tissue. Accuracy was 89% in individuals with amyloid plaques and tangles, and 98% in individuals with plaques and more extensive tangles.

The third cohort consisted of 622 members of a large extended family in Colombia whose members share a genetic mutation that makes them susceptible to early-onset Alzheimer’s, The New York Times reported. Among the members, 365 were carriers of the mutation. In this group, levels of plasma p-tau217 increased by age, and “a significant difference from noncarriers was seen at age 24.9 years,” the researchers wrote in Jama Network. That’s about 20 years before the median age when mild cognitive impairment typically begins to appear in carriers.

Other Alzheimer Biomarker Studies Presented at AAIC

Suzanne Schindler, MD, PhD, a neurologist and instructor in the Department of Neurology at the Washington University School of Medicine (WUSM) in St. Louis, presented results of an Alzheimer’s Disease (AD) study that used mass spectrometry to analyze amyloid and p-tau variants in blood samples collected from participants. The researchers compared these with CSF and PET results and found that some of the of p-tau isoforms, especially p-tau217, had a strong concordance.

“These findings indicate that blood plasma Aβ and p-tau measures are highly precise biomarkers of brain amyloidosis, tauopathy, and can identify stages of clinical and preclinical AD,” stated an AAIC press release on the studies.

The WUSM researches launched the effort to develop and validate Alzheimer’s blood biomarkers called the Study to Evaluate Amyloid in Blood and Imaging Related to Dementia (SEABIRD) in April 2019. It runs through August 2023 and will seek to enroll more than 1,100 participants in the St. Louis area.

Another study presented at the conference compared the performance of p-tau217 and p-tau181 in distinguishing between Alzheimer’s and Frontotemporal Lobar Degeneration (FTLD), another condition that causes dementia. Study author Elisabeth Thijssen, MSc, of the UC San Francisco Memory and Aging Center reported that both biomarkers could be useful in differential diagnosis, but that p-tau217 was “potentially superior” for predicting a tau positive PET scan result.

For decades, physicians have wanted a diagnostic test for Alzheimer’s Disease that could identify this condition early in its development. This would allow the patient and the family to make important decisions before the onset of severe symptoms. Such a clinical laboratory test would be ordered frequently and thus would be a new source of revenue for medical laboratories.

—Stephen Beale

Related Information:

How is Alzheimer’s Disease Diagnosed?

Alzheimer’s Diagnosis and Treatment

Diagnosing Alzheimer’s: How Alzheimer’s is Diagnosed

New Alzheimer’s Disease Blood Test Could Enable Early Diagnosis and Advance Understanding of How Disease Impacts Those Living with It

Lilly’s p-tau217 Blood Test Shows High Accuracy in Diagnosis of Alzheimer’s Disease in Data Published in JAMA

P-Tau217 May Detect Alzheimer Disease, Brain Amyloidosis, Tauopathy

New Blood Test Shows Great Promise in The Diagnosis of Alzheimer’s Disease

‘Amazing, Isn’t It?’ Long-Sought Blood Test for Alzheimer’s in Reach

Scientists Get Closer to Blood Test for Alzheimer’s Disease

Discriminative Accuracy of Plasma Phospho-tau217 for Alzheimer Disease vs Other Neurodegenerative Disorders

Clinical Laboratory Test for Alzheimer’s Disease Gets Ever Closer to Reality

Scientists worldwide engaged in research to develop a biomarker for dementia are predicting success, though some say additional research will be needed

Could a blood test for Alzheimer’s disease soon be on clinical laboratory test menus nationwide? Perhaps so. A recent Associated Press (AP) article that was picked up by NBC News and other healthcare publications reported that experimental test results presented during the Alzheimer’s Association International Conference (AAIC) in July suggest the Holy Grail of dementia tests—one where the specimen can be collected in a doctor’s office during a routine screening exam—may be close at hand.

The AP story noted that “half a dozen research groups gave new results on various experimental tests, including one that seems 88% accurate at indicating Alzheimer’s risk.” And Richard Hodes, MD, Director of the National Institute on Aging, told AP, “In the past year, we’ve seen a dramatic acceleration in progress [on Alzheimer’s tests]. This has happened at a pace that is far faster than any of us would have expected.”

This could be a boon for medical laboratories seeking way to contribute more value to patient care. Especially among Alzheimer’s patients, who account for as many as 70% of all dementia cases.

Plasma Biomarker for Predicting Alzheimer’s

One of the experimental blood tests presented at the AAIC involved a 2018 study into “the potential clinical utility of plasma biomarkers in predicting brain amyloid-β burden at an individual level. These plasma biomarkers also have cost-benefit and scalability advantages over current techniques, potentially enabling broader clinical access and efficient population screening,” the researchers stated an article they published in Nature.

Dark Daily reported on this study in “Researchers in Two Countries Develop Blood Tests That Detect Alzheimer’s Decades Before Symptoms Appear; Could Eventually Give Clinical Laboratories a Diagnostic Tool,” June 4, 2018. The test “measures abnormal versions of the protein [amyloid beta] that forms the plaques in the brain that are the hallmark of Alzheimer’s,” the AP story reported.

AP also reported that Japanese scientists at the AAIC presented results of a validation test conducted on 201 people who had either Alzheimer’s, other types of dementia, or little or no symptoms. They found that the test “correctly identified 92% of people who had Alzheimer’s and correctly ruled out 85% who did not have it, for an overall accuracy of 88%.”

Akinori Nakamura, MD, PhD, of the National Center for Geriatrics and Gerontology in Obu, Japan, was a member of the research team and first author of the research paper. He told the AP that the test results “closely matched those from the top tests used now—three types of brain scans and a mental assessment exam.”

Eric McDade, DO (above), Associate Professor of Neurology at Washington University in St. Louis, told Neurology Today, “The results reported here provide a relatively high level of confidence given that this is a relatively well characterized population with an amyloid PET scan to provide confirmation of a significant level of amyloid plaque burden in the brain.” Could this level of physician confidence lead to a clinical laboratory test based on the plasma biomarker? (Photo copyright: Washington University.)

Koichi Tanaka is a Japanese engineer who won the Nobel prize winner for chemistry. He heads the Koichi Tanaka Research Lab at Shimadzu Corp. (OTCMKTS:SHMZF) in Kyoto, Japan, and was on the team that developed the Amyloid beta biomarker test that was presented at AAIC. He told Bloomberg, “Our finding overturned the common belief that it wouldn’t be possible to estimate amyloid accumulation in the brain from blood. We’re now being chased by others, and the competition is intensifying.”

But Tanaka cautions that the test needs further study before it is ready for clinical use, and that for now “it belongs in the hands of drug developers and research laboratories,” Bloomberg reported.

Other Studies into Developing an Alzheimer’s Biomarker

Alzheimer’s is usually diagnosed after symptoms appear, such as memory loss. To arrive at their diagnoses, doctors often rely on medical history, brain imaging (MRI, CT), PET, and measurement of amyloid in spinal fluid.  

An article published on Alzforum, a website and news service dedicated to the research and treatment for Alzheimer’s and other related disorders, noted a study by King’s College London researchers who, using mass spectrometry, “found a panel of biomarkers that predicted with almost 90% accuracy whether cognitively normal people had a positive amyloid scan.”

Nicholas Ashton, PhD, neuroscientist and Wallenberg Postdoctoral Fellow at University of Gothenburg in Sweden, and first author of the King’s College study, explained that “Amyloid-burden and neurofilament light polypeptide (NFL) peptides were important in predicting Alzheimer’s, but alone they weren’t as predictable as when we combined them with novel proteins related to amyloid PET.”

The researchers published their study earlier this year in Science Advances. “Using an unbiased mass spectrometry approach, we have found and replicated with high accuracy, specificity, and sensitivity a plasma protein classifier reflecting amyloid-beta burden in a cognitively unimpaired cohort,” the researchers wrote.

Meanwhile, researchers at Washington University School of Medicine St. Louis, along with the German Center for Neurodegenerative Diseases, a member of the Helmholtz Association, stated in a news release that a blood test they developed works by detecting leaks of NFL before the onset of symptoms. When the protein is found in cerebrospinal fluid, it could be a sign that Alzheimer’s may develop, as well as point to other neurodegenerative conditions such as multiple sclerosis, brain injury, or stroke, the researchers stated.  

“This is something that would be easy to incorporate into a screening test in a neurology clinic,” Brian Gordon, PhD, Assistant Professor of Radiology at Washington University’s Mallinckrodt Institute of Radiology, and an author of the study, stated in the news release.

These parallel studies into screening for Alzheimer’s by researchers worldwide are intriguing. The favorable results suggest that someday there may be a screen for Alzheimer’s using a clinical laboratory blood test.

With Alzheimer’s affecting nearly six million Americans of all ages, such an assay would enable clinical laboratories to help many people.

—Donna Marie Pocius

Related Information:

Scientists Close in On Blood Test for Alzheimer’s

Advances in the Global Search for Blood Markers for Alzheimer’s Disease and Other Dementias

A Blood Test Can Predict Dementia. Trouble Is, There’s No Cure

Plasma Biomarker for Amyloid Correlates with Alzheimer’s Progression, Study Finds

High Performance Plasma Amyloid-β Biomarkers for Alzheimer’s Disease

Panel Blood Markers Signals Amyloid in Brain

A Plasma Protein Classifier for Predicting Amyloid Burden for Preclinical Alzheimer’s Disease

Blood Test Detects Alzheimer’s Damage Before Symptoms; Test Also May Identify Neurodegeneration in Other Brain Diseases

Blood-Brain Barrier Breakdown is an Early Biomarker of Human Cognitive Dysfunction

Researchers in Two Countries Develop Blood Tests That Detect Alzheimer’s Decades Before Symptoms Appear Could Eventually Give Clinical Laboratories A Diagnostic Tool

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