Latest / Morning Medical with Dr. Chow / New Alzheimer's Blood Test, Global Dengue Fever Rise, and Air Pollution Crisis

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New Alzheimer's Blood Test, Global Dengue Fever Rise, and Air Pollution Crisis · Morning Medical with Dr. Chow

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Good morning and welcome to another episode of Morning Medical with Dr.
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Chow.
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I am your host, Dr.
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Chi-Ming Chow, coming to you with the latest updates in medical and health news from around
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the world.
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Today, we have some groundbreaking news in the field of Alzheimer's research that could
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potentially revolutionize early diagnosis and treatment.
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A new study has found that a combined blood test for cognitive decline has an impressive
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ninety percent accuracy rate in determining whether memory loss is due to Alzheimer’s
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disease.
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This is a significant improvement compared to the accuracy rates of neurologists and other
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memory specialists, who correctly diagnosed Alzheimer’s in seventy-three percent of their
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cases.
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Primary care doctors had even less success, with only a sixty-one percent accuracy rate.
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One part of the blood test, called plasma phosphorylated tau 217, or p-tau217 for short,
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is one of several blood biomarkers scientists are evaluating for use in the diagnosis of mild
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cognitive impairment and early-stage Alzheimer’s disease.
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The test measures tau protein 217, which is an excellent indicator of amyloid pathology.
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Dr.
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Sebastian Palmqvist, an associate professor and senior consultant neurologist at Lund
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University in Sweden, noted that increases in p-tau217 concentrations in the blood are quite
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profound in Alzheimer’s disease.
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At the dementia stage of the disease, levels are more than eight times higher compared with
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elderly individuals without Alzheimer’s.
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Research published earlier this year found that a similar p-tau217 test is up to ninety-six
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percent accurate in identifying elevated levels of beta-amyloid and up to ninety-seven percent
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accurate in identifying tau.
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The presence of beta-amyloid and tau tangles in the brain are hallmark signs of Alzheimer’s
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disease.
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In the new study, the p-tau217 test was combined with another blood biomarker for
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Alzheimer’s called the amyloid 42/40 ratio, which measures two types of amyloid proteins.
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This combination, known as the amyloid probability score, was the most predictive.
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Dr.
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Maria Carrillo, chief science officer of the Alzheimer’s Association, expressed optimism
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about the new test.
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'We’d love to have a blood test that can be used in a primary care physician’s office,
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functioning like a cholesterol test but for Alzheimer’s,' she said.
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'The p-tau217 blood test is turning out to be the most specific for Alzheimer’s and the one
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with the most validity.
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It seems to be the front-runner.' Once fully vetted, highly accurate blood tests could
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'change the game in the speed in which we can conduct Alzheimer’s trials and get to the next
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new medication,' she added.
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'These are absolutely transformational times.'
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So, how does a p-tau217 blood test work?
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The peptide p-tau217 is unique in that it can be detected only when amyloid plaques are
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present in the brain.
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'What that means to us scientifically is that when we’re measuring p-tau217, we’re measuring
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the neuronal damage from tau very early on in Alzheimer’s, but only when amyloid is already
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present,' said Carrillo.
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'You’re not really measuring amyloid, but the test is telling you it’s there, and that’s been
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backed up with objective PET scans that can see amyloid in the brain.'
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It’s crucial to note that tau tangles are implicated in several other neurological
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diseases such as frontal lobe dementia, or FTD.
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In FTD, tau tangles attack the brain’s frontal lobe, causing behavioral and emotional changes
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and the loss of executive functions such as planning.
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Memory loss, if it occurs, happens much later.
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In Alzheimer’s, tau tangles build up in the part of the brain controlling memory, but
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amyloid plaques play a key role.
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Small clusters of plaques can gather at synapses and interfere with the nerve cells’
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ability to communicate.
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Amyloid plaques may also overstimulate the immune system, triggering inflammation that may
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further damage the brain.
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Some of the newest drugs for dementia, such as lecanemab and donanemab, target beta-amyloid
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and are thought to be less effective in people with advanced tau pathology.
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Because deposits of amyloid can begin accumulating in the brain decades before
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symptoms begin, even when a person is in their thirties or forties, an early diagnosis of
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brain amyloid could be critical for lifestyle modifications and preventive treatment with
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medications.
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The study, published in the journal JAMA Neurology, followed one thousand two hundred
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and thirteen people with an average age of seventy-four who were undergoing cognitive
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evaluations in both primary care and specialty clinics in Sweden.
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Each person’s blood was tested using p-tau217, and the results were combined with blood
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measures of beta-amyloid 40/42 to develop a final score.
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'When you use a combination of the 40 to 42 ratio and p-tau217, it increases the diagnostic
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accuracy of p-tau217,' said preventive neurologist Dr.
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Richard Isaacson, director of research at the Institute for Neurodegenerative Diseases in
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Florida, who was not involved in the study.
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The ninety percent accuracy of the study’s combined blood test was confirmed via a spinal
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fluid tap, which along with an amyloid PET scan is currently the only gold-standard scientific
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method other than autopsy for diagnosing Alzheimer’s.
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Both tests are expensive, invasive, and not readily available across the United States.
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The results of the blood tests were then measured against patient diagnoses provided by
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Swedish primary care doctors and specialists.
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The relatively poor rate of accuracy — sixty-one percent and seventy-three percent —
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highlights how difficult it is for doctors to correctly identify Alzheimer’s pathology with
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current tools: a short interview with the patient, a brief cognitive test, and a computed
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tomography scan of the brain.
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Dr.
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Oskar Hansson, a professor and senior consultant of neurology at Lund University,
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pointed out that 'generally, both traditional paper-and-pen tests and digital cognitive
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assessments are not highly accurate in specifically identifying Alzheimer’s disease.
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Many other conditions and diseases can present similar cognitive symptoms, leading to
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potential misdiagnosis or missed diagnosis.' In fact, between twenty percent and thirty percent
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of patients seen by specialists take medications or have other medical conditions
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that can mimic Alzheimer’s disease.
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Diseases that may affect cognitive function include vascular dementia, depression, thyroid
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disease, sleep apnea, and even vitamin B12 deficiency.
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If those mimics are not caught during the initial exam, people with no Alzheimer’s
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pathology can clog up waiting lists for specialists and appointments for spinal taps
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and amyloid PET scans.
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By the time someone with true amyloid pathology sees a specialist, they may 'fall out of that
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window of being eligible for the drugs we have, and that’s terrible,' Carrillo said.
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Wait times are only going to get worse, according to mathematical models based on the
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aging of the United States population.
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By two thousand thirty-three, if a primary care doctor uses only the current cognitive
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assessments to determine dementia, people will wait an average of nearly six years before
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finding out whether they are eligible for new Alzheimer’s treatments.
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However, if accurate blood tests are used, wait times may drop to between six and thirteen
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months, because far fewer people would need to see a specialist or undergo additional testing.
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Do not expect blood tests for Alzheimer’s to routinely pop up in your primary doctor’s
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office anytime soon, however.
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More research is needed to verify the positive results appearing in studies, guidelines for
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physician use must be established and distributed, and physicians have to be educated
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about any possible nuances.
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'There’s no one more bullish on these tests than I am, but Alzheimer’s blood tests aren’t
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fully definitive yet,' said Isaacson.
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'If it is a positive test, it still needs to be confirmed via PET scan or spinal tap.
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If it’s a negative result, that’s reassuring, but if it’s borderline, we still don’t know
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what that means.'
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In the meantime, research has shown there are many actions people can take to prevent or slow
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cognitive decline, including getting regular exercise, eating a Mediterranean-style diet,
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and treating vascular risk factors like high blood pressure, high cholesterol, and diabetes.
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'It’s our goal to use only the highest-quality blood tests to not only help make an early
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diagnosis of Alzheimer’s but also evaluate response to risk-reducing interventions,'
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Isaacson said.
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'These are very hopeful times.'
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The rise in global travel and climbing temperatures are contributing to a surge in
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dengue fever cases, according to Dr.
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Claire Panosian Dunavan, a professor of medicine and infectious diseases at the David
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Geffen School of Medicine at the University of California, Los Angeles.
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Dr.
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Dunavan, who is also a past-president of the American Society of Tropical Medicine and
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Hygiene, highlights the concerning trend in a recent article for MedPage Today.
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The Centers for Disease Control and Prevention recently issued a health advisory that
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underscores the gravity of the situation.
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While 2023 saw 4.6 million reported cases of dengue in the Americas, the number had already
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doubled to 9.7 million by June 24 of this year.
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And remember, this increase occurred before the region entered its highest-transmission months.
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Most U.S.
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cases of dengue are linked to overseas travel, which has surged as concerns over COVID-19 have
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waned.
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But as more people travel, local cases can also rise.
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At least thirty U.S.
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states harbor the Aedes aegypti and Aedes albopictus mosquitoes, which can transmit
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dengue from an infected traveler to others.
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Autochthonous transmission, or local spread within the United States, is not a new
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phenomenon.
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Although the dengue virus was not isolated until 1945, epidemics are thought to have
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occurred in major southern cities and Philadelphia as far back as the eighteenth and
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nineteenth centuries.
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Dengue re-emerged in the 1980s, causing periodic local outbreaks and sporadic cases in
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Florida, Hawaii, Texas, and more recently, Arizona and California.
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Today, 3.6 billion people in over one hundred countries live in dengue-endemic areas.
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The world now experiences an estimated four hundred million yearly infections, leading to
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one hundred million clinical illnesses and twenty-one thousand deaths, largely affecting
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children.
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Several factors contribute to this dramatic rise in what was once a neglected tropical
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disease: the global spread of dengue's four serotypes, the expanded distribution of Aedes
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mosquitoes, their tendency to breed in man-made habitats, unprecedented urbanization, and
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climate change.
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Rising temperatures lead to faster replication of the virus, more fecund vectors, higher bite
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rates, and longer transmission seasons.
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Dr.
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Dunavan shares a story from 2002 about an East Coast couple whose South Pacific honeymoon
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turned into a nightmare when the newlywed bride developed severe dengue symptoms.
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She experienced chills, fever, a rash, and bleeding gums, and required hospitalization.
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Although she recovered, she remained severely fatigued for months.
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Dr.
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Dunavan also recounts the experience of her friend Roxanne, who fell ill after a trip to
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Austin, Texas, in 2013.
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Despite seeing several doctors, it was a non-medical friend who suggested dengue.
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Roxanne's illness was confirmed only after she requested a dengue test herself.
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These stories highlight the importance of considering dengue in the differential
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diagnosis, especially for travelers returning from endemic areas.
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Dr.
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David O.
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Freedman, a travel medicine expert at the University of Alabama at Birmingham, has spent
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decades studying tropical diseases.
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He emphasizes the importance of preventive measures like wearing long sleeves and pants,
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using insect repellent, and avoiding outdoor dining in high-risk areas.
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Dr.
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Freedman is also closely monitoring the development of new dengue vaccines.
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The World Health Organization recently endorsed a new dengue vaccine for people up to sixty
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years of age, prioritizing six- to sixteen-year-olds in high-transmission areas.
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However, questions remain about its efficacy for long-term travelers or medical workers in
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high-risk settings.
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The World Health Organization has suggested that the new vaccine could be considered for
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long-stay travelers, but more research is needed.
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As we navigate these worrisome trends, the hope is that next-generation vaccines will offer
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full protection against all four dengue serotypes, shielding more people from this
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increasingly prevalent disease.
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Until then, preventive measures and heightened awareness remain crucial.
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Our third and final topic today is a pressing global health crisis that demands urgent
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interdisciplinary action: air pollution.
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A recent review article published in the journal Science, authored by Dr.
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Sanchari Sinha Dutta, highlights the severe health effects of air pollution and the
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challenges associated with monitoring population exposure, particularly in low- and
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middle-income countries and among vulnerable populations.
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Exposure to ambient air pollution, including particulate matter and greenhouse gases, is
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associated with increased risks of various non-communicable diseases.
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Ambient particulate matter has been classified as a group I human carcinogen for lung cancer.
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An estimated 5.2 million deaths occur each year globally due to air pollution.
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The World Health Organization updated the Global Air Quality Guidelines for air
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pollutants in 2021 to reduce the public health burden.
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These guidelines are based on evidence from recent studies investigating the adverse health
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effects of global air pollution.
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Non-communicable diseases are associated with a significant percentage of global mortality and
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disability, accounting for almost 41 million deaths per year, with seventy-seven percent
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occurring in low- and middle-income countries.
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About ninety-nine percent of the global population is continuously exposed to
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poor-quality air that exceeds the World Health Organization's guideline limits.
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Populations with increased vulnerability due to age, sex, and disease status are at higher risk
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from the damaging effects of air pollution exposure.
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Racial and ethnic disparities in air pollution-attributable premature mortality have
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also increased over the decades.
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Air pollution is primarily caused by complex mixtures of particulate matter, including black
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carbon and polycyclic aromatic hydrocarbons, various greenhouse gases like nitrogen dioxide,
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sulfur dioxide, carbon monoxide, and volatile organic compounds.
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These pollutants are generated from a range of man-made sources, including residential and
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commercial energy use, agricultural and industrial emissions, biomass burning, and
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vehicle emissions, as well as natural sources such as wildfires and volcanoes.
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One of the major challenges in accurately estimating global air pollution exposure is
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that ground-based air quality monitoring is primarily done in urban areas.
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In low- and middle-income countries, the development of local emission inventories is
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needed to predict anthropogenic emission sources and trends accurately.
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Rapid alterations in agricultural activity should be considered for improving emission
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estimates' accuracy.
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Improved exposure models combining satellite-derived data with ground-based
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monitor-derived data, chemical transport models, and emission inventories have improved
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global estimates and long-term trends of particulate matter at finer scales.
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In addition to conventional monitoring, filter-based particulate matter source
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apportionment has often been applied to principal component analysis, positive matrix
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factorization, and advanced exposure models to prioritize policies for regulation and to
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identify the sources of air pollution.
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The emerging application of low-cost air pollution monitors may provide further data to
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monitor exposure to air pollutants at the level of individuals, which could be especially
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valuable for those who tend to spend much time indoors, such as schoolchildren, pregnant
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women, and persons with preexisting diseases.
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An induction in the levels of air pollutants, including particulate matter and ozone, has
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been found to be associated with increased risks of mortality, morbidity, and
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hospitalization.
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A range of clinical consequences of air pollution exposure has been observed in people
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with metabolic diseases like diabetes and obesity, neurological disorders such as
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dementia, and kidney and immune diseases.
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The global burden of death attributed to ambient particulate matter exposure in 2021 was
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dominated by cardiopulmonary diseases in both females and males, with the greatest impact
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among those eighty years of age and older.
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Recent evidence indicates that small-diameter particulate matter can exert adverse health
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effects even at very low concentrations.
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Ozone, the most prevalent secondary pollutant, has been found to have a causal association
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with respiratory diseases.
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It is also plausible that a spectrum of pediatric disorders associated with air
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pollution may lead to underappreciated consequences and may manifest as heightened
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risks of non-communicable diseases throughout the life span.
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Higher ventilation rates and underdeveloped immunity make young children more susceptible
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to air pollution-related health adversities.
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Maternal physiological changes during pregnancy can also make both mother and fetus vulnerable
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to air pollution.
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A recent review of thirty-two million births in the United States showed associations between
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ambient particulate matter and ozone with increased risks of adverse birth outcomes,
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including preterm birth and stillbirth.
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The best possible intervention to improve air quality is to reduce ambient levels of air
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pollutants and risk communication to the government and stakeholders.
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Smokestack controls on power plants and large industries, tailpipe controls on motor
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vehicles, promotion of public transport and nonmotorized transport, electrification of
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homes and businesses, and promotion of good practices in agriculture and farming are some
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of the government-implemented policies to improve air quality.
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The best possible way to reduce air pollution exposure is to stay indoors or reduce outdoor
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activity during high-pollution days.
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However, it is not feasible, or even advisable, for people living in low- and middle-income
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countries, highlighting the impact of socioeconomic inequity on the accessibility to
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clean air.
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These observations highlight the urgent need to develop and implement evidence-based air
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quality policies for protecting public health, especially in low- and middle-income countries.
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From the perspective of air quality management, developing evidence-based risk communication
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indices to provide timely air quality and health information can bridge knowledge gaps
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across sectors and improve the effectiveness of interventions at the government and public
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levels.
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That wraps up today’s episode of Morning Medical with Dr.
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Chow.
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We covered some groundbreaking advancements in Alzheimer's diagnosis, the surge in dengue
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fever cases, and the pressing global health crisis posed by air pollution.
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I hope you found these updates informative and valuable.
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Stay tuned for more on the latest in medical and health news.
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Until next time, stay healthy and take care.