AMA Update covers a range of health care topics affecting the lives of physicians, residents, medical students and patients. From private practice and health system leaders to scientists and public health officials, hear from the experts in medicine on COVID-19, medical education, advocacy issues, burnout, vaccines and more.
Featured topic and speakers
How is Alzheimer's diagnosed? Is there a new blood test for colon cancer? Is West Nile virus deadly? Is West Nile virus curable? How bad is COVID right now?
Our guest is AMA Vice President of Science, Medicine and Public Health Andrea Garcia, JD, MPH. AMA Chief Experience Officer Todd Unger hosts.
- The AMA is your powerful ally in patient care. Join now.
- For more on the new blood test detects Alzheimer's disease: "Blood Biomarkers to Detect Alzheimer Disease in Primary Care and Secondary Care" JAMA study.
- Get the latest New England Journal of Medicine study on the Shield blood test for colon cancer.
- CDC guidelines on West Nile virus symptoms, West Nile transmission and more.
Speaker
- Andrea Garcia, JD, MPH, vice president, science, medicine & public health, American Medical Association
Transcript
Unger: Hello and welcome to the AMA Update video and podcast. Today, we have our weekly look at the headlines with the AMA's Vice President of Science, Medicine and Public health, Andrea Garcia. I'm Todd Unger, AMA's chief experience officer. Welcome back, Andrea.
Garcia: Thanks for having me, Todd. It's good to be here.
Unger: We got a lot to talk about, starting with two new blood tests that could revolutionize patient care that made headlines this week. One could help physicians diagnose Alzheimer's, and the other detects colon cancer. Both could prove to be hugely beneficial diagnostic tools. Andrea, let's begin with the Alzheimer's test. What do we need to know there?
Garcia: Yeah, Todd, there was a study published in JAMA that found a simple blood test correctly identified whether patients with memory problems had Alzheimer's disease about 90% of the time. And this was a huge finding because the blood test proved more accurate than the standard evaluation, so a clinical exam, cognitive testing and a CT scan. I think to put this into context, dementia specialists using those standard methods that did not include PET scans or invasive spinal taps were accurate about 73% of the time. And then primary care doctors using those methods got the diagnosis right about 61% of the time.
These results were presented last weekend at the Alzheimer's Association International Conference in Philadelphia. They were then covered by The New York Times. However, that new research was conducted in Sweden, and experts are cautioning that for use here in the U.S., the results really should be confirmed in a diverse population. That said, as an expert in the New York Times article pointed out, it wasn't too long ago that measuring pathology in the brain of a living human was considered just impossible. So that really gives you some idea of just how far we've come.
Unger: That is quite a long way. Andrea, what impact do you see this having on patient care?
Garcia: Well, we know that Alzheimer's disease affects nearly 7 million Americans and over 32 million people worldwide. So, any step that we can take toward developing affordable and accessible ways to diagnose the disease is going to be incredibly helpful. Some experts believe that there may be a day when people receive routine blood tests for cognitive impairment as a part of a primary care checkup, similar to the way we receive cholesterol tests.
And they could prove to be very valuable screening tools. Blood tests like these may also help physicians identify patients who are eligible for certain medications by pinpointing the cause of cognitive decline. I think the thing to keep in mind is, there are certain limitations. The researchers in the study cautioned that blood tests should really be a part of a larger screening process. The results should be confirmed by one of the gold standard methods, so amyloid PET scans or spinal taps. And they also said that the blood test should only be used for people with memory loss or other symptoms of cognitive decline. It shouldn't be used as a predictive tool to tell people if they will develop Alzheimer's in the future.
Unger: I see. Why is that?
Garcia: Well, when we consider screening tests, we're really looking at the risks and the benefits. And if there are no therapies to offer someone who has currently no symptoms of cognitive decline, and then we couple that with the risk of anxiety or psychological reactions to a test, the risks may outweigh the benefits at this point. Until preventive treatments are available, doctors would likely decide who's eligible and weigh the risks and benefits. I think if there are new preventive treatments that are developed, those testing recommendations would likely change. But until then, we'll have to wait for more evidence in this area.
Unger: Well, thank you so much for that update. Turning to the other blood tests that made news this week, the one that detects colon cancer. Andrea, tell us more about that.
Garcia: Yeah, this one was reported on by the Associated Press. And this blood test was actually approved by the FDA earlier this week. This is known as the SHIELD test. It's the first of its kind blood tests for colon cancer. It's approved for screening adults who are 45 and older who have an average risk of colon cancer. Prior to this, doctors could order SHIELD for patients as a lab test, but it came with a hefty out-of-pocket price of about $895. The FDA approval is expected to increase coverage by private and government insurance, and hopefully, make it more affordable for many.
Unger: Andrea, how exactly does that test work?
Garcia: Well, that test looks for DNA fragments that are shed by tumor cells and precancerous growths. And in a study published in March, the tests caught about 83% of cancers but very few of the precancerous growths that are found by a colonoscopy, which means that the gold standard for colon cancer screening remains to be that colonoscopy. The test missed about 17% of cancers, which is pretty much on par with the stool-based tests that you see on the market.
Unger: So if a colonoscopy is still the gold standard, how do you see a test like this fitting into current screening protocols?
Garcia: Well, I think one of the biggest challenges in diagnosing colon cancer is that many people who are eligible for a colonoscopy tend to avoid them. And whether that's because they don't want to take the time off work, or they're put off by the uncomfortable prep leading up to the procedure, or for some other reason, this test really provides people with another option, and it only involves a simple blood draw. The annual rate of U.S. colon cancer screening is only about 60%, and we know that is well short of the 80% goal that has been set by the American Cancer Society and other groups. So, this noninvasive blood test could certainly help get us closer to that number and then, ultimately, save lives.
Unger: Well, thank you so much. Certainly, incredible new tools for physicians. Let's turn to a different topic that's in the not-so-good news category. Andrea, apparently, we're seeing an uptick in West Nile virus here in the United States. What can you tell us about that?
Garcia: Well, Todd, there are so many things to love about summer. Mosquitoes definitely aren't one of them. There was a recent CNN Health article that noted about 1,000 people in the U.S. are hospitalized each year with the most severe form of West Nile virus, and about another 1,500 people are diagnosed with the less severe form. And these may not sound like huge numbers, but health experts worry that rising temperatures could mean that West Nile virus will become more prevalent. Since most cases of West Nile are mild and symptoms are not always specific, Experts estimate that as many as 80% of infections here are never caught or counted.
Unger: So what's causing the big concern right now?
Garcia: Well, this year, West Nile activity has picked up earlier than usual. So the heaviest activity is typically seen in August and September. And experts are worried that this could be a precursor to a difficult season. According to CNN, we typically see those larger spikes in West Nile activity about every 10 years. And the last big jump in cases was seen in 2012, so we could certainly see another one this year.
Some experts are zeroing in on Houston as a potential hotspot for the disease, and that's because of Hurricane Beryl. The Director of Mosquito Control for Harris County Public Health in Texas says that his department has seen 500 pooled samples of mosquitoes test positive for the virus this year already. And if we put that into context, only 50 pools tested positive all of last year.
Unger: Wow. So I'm known to my family as a person who will break things in the house in pursuit of a mosquito. This is not going to help. Andrea, what symptoms do we need to watch for, and are there any vaccines or treatments for West Nile?
Garcia: Well, in the most severe form of West Nile, the infection impacts the brain and the nervous system. It can cause paralysis and possibly even death. In the less severe, more common form, it's usually fever or flu-like symptoms and a rash. Unfortunately, there are no treatments. And while vaccine candidates are in development, none are in phase III trials, which we know are going to be needed for FDA approval.
The challenge of a phase III trial for this vaccine include the unpredictable and sporadic nature of the outbreaks that we see. So prevention here is really key. Be sure to use EPA-registered insect repellent, particularly at dawn and dusk when we know mosquitoes are most active. And then long pants and long sleeves can also help.
It's also smart to check with your local health department. They can share whether West Nile virus has been detected in your area. And the CDC also has maps of where West Nile cases have been detected in the U.S. We do know that this year, human infections have been reported across 19 states so far.
Unger: Well, thank you. That's good to know. Andrea, before we sign off, let's do a quick check in on COVID. How are the numbers doing out there?
Unger: Well, according to wastewater data from the CDC, COVID is still surging across the U.S. with levels of the virus on track to exceed last year's summer wave nationally. That surge continues to be fueled in part by the FLiRT variants in particular. One of them, known as KP.3.1.1 has really increased. The CDC estimates that strain accounted for about 17.7% of COVID samples nationwide for that two-week period, which ended July 20. That's up from 6.8% for that comparable period the prior week.
I think updated vaccines are in development as we know, but they won't be available until the fall. So in the meantime, you can take steps to protect yourself and those around you. And if you have symptoms, be sure to test. Obviously, knowing if you have COVID is important so you can take precautions to keep it from spreading. And of course, access recommended treatments if you're at risk for severe illness.
Unger: Absolutely. That's great advice to finish off the week. Andrea, thank you, as always, for being here and sharing this information. If you found this discussion valuable, you can support more programming like it by becoming an AMA member at ama-assn.org/join. You can find all our videos and podcasts at ama-assn.org/podcasts. Thanks for joining us today. Please take care.
Disclaimer: The viewpoints expressed in this podcast are those of the participants and/or do not necessarily reflect the views and policies of the AMA.
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