JOE PALCA, host:
This is Talk of the Nation Science Friday from NPR News. I'm Joe Palca sitting in for Ira Flatow. Later in the hour, we'll talk with brain scientist Jill Bolte Taylor. Her new book is called "My Stroke of Insight: A Brain Scientist's Personal Journey." To start the hour, we'll look at the latest research news on stroke. There's a new study that looks at how often silent strokes happen in otherwise healthy adults. Silent strokes are tiny strokes that go unnoticed because they don't have any obvious clinical symptoms. The researchers did MRIs on more than 2,000 healthy adults. They looked at the brain scans for signs of stroke.
Then they look risk factors, more visible signs of trouble, known to be associated with stroke and tried to determine if those could also predict whether a person had these small silent strokes. Joining me to talk about this study out in the current issue of the journal, Stroke, is my guest Sudha Sasedra - Seshadri, I'm sorry, Sudha Seshadri . She's an investigator with the Framingham Heart Study, an associate professor in the Department of Neurology at Boston University. She joins me today from her office. Welcome to the program, Dr. Seshe - Seshadri.
Dr. SUDHA SESHADRI (Investigator, Framingham Heart Study; Associate Professor, Department of Neurology, Boston University): Seshadri.
PALCA: I'm terribly sorry. I had it, I practiced it, and I completely lost it. Thank you for joining us. And if you have questions that you like to ask Dr. Seshadri about stroke, and other questions about what - our topic, you can call us. Our number is 800-989-8255. That's 800-989-TALK. And there is more information at www.sciencefriday.com where you'll find links to our topic. And I guess the first question is who were these 2,000 patients that you were studying?
Dr. SESHADRI: So good afternoon, Joe, I enjoy your show and I am delighted to be here.
PALCA: Oh, good.
Dr. SESHADRI: The Framingham Heart Study has been following residents of the town of Framingham since 1948. And in 1971, children of the original participants, as well as, spouses of these children were enrolled because we wanted to follow a new generation to look for any changes in these diseases and associated risk factors. In 1999, we had been increasingly recognizing that a clinical stroke or a clinical heart attack really is a tip of the iceberg. And that the same risk factors that result in the clinical disease, probably caused sub-clinical, more subtle damage and to look at this we choose sensitive research MRI, which was done in all these Framingham offspring, who could have an MRI. That is if somebody was not claustrophobic, does not have, you know, metal in their head so they could not have an MRI, that sort of thing. So this was a study sample. We have been following these people very carefully for neurological disease, including stroke. So we choose to look at only those people who we knew did not have a clinical stroke, did not have dementia, Alzheimer, multiple sclerosis, brain tumors, you know, significant head injuries, things like that.
PALCA: Now, if these are silent strokes, as they're called, and they don't cause a clinical - a significant clinical disruption that you could notice, why worry about them?
Dr. SESHADRI: Right, the reason to worry is because some researchers prefer to call them covert infarcts or MRI infarcts. The word covert as opposed to overt. When we look at the MRI, we really can't distinguish them from symptomatic stroke or a stroke with signs. But we know that these people never had signs or symptoms. However, if you do very careful and detailed testing, you do find that there are subtle changes. On an average, if you take a group of people of the same age and sex and same risk factors, those you have these silent, and so called silent infarcts, would do a little worst on tests of - sophisticated tests of thinking. Like attention, executive function, you know, planning, sequencing tasks. How long it takes them to do tasks. They may also - they have a greater probability of developing clinical stroke, as well as of developing decline in their cognitive function of developing dementia on follow up. And so these are reasons to take this, apparently silent, damage previously.
PALCA: Yeah, so they may appear innocuous but they may be a hint of something to come. Interesting.
Dr. SESHADRI: That's exactly right.
PALCA: OK, let's take one call from one of our listeners now and go to Mary in Barnegat, New Jersey. Mary, welcome to Science Friday.
MARY (Caller): Yes, thank you. Doctor, I am curious as to whether this study produced any more risk factors, or identified any more risk factors for these types of strokes and other types of strokes, other than what have been previously been identified.
Dr. SESHADRI: No, we did not look at any new risk factors. In fact, the way we designed the study was to look at very well known, as well as, relatively novel but known risk factors for clinical stroke and we wanted to see what - whether this same risk factors were associated with sub-clinical stroke, as well as, how large this association was.
PALCA: I see. Mary, thanks very much for that question.
MARY: Thank you.
PALCA: Are there some risk factors among the ones that you look at that are more important than others?
Dr. SESHADRI: We found that blood pressure, having a high blood pressure, having hypertension was the most important. If we were able to removed hypertension in a population - this is obviously a theoretical construct. About 16 percent of all these silent strokes would not be there. In addition, we found that having a narrowing of the carotid artery, having thickness of the inner lining of the carotid, which is a marker of very early atherosclerotic changes, having a high level of an amino acid called plasma homocysteine, having an irregular heartbeat called atrial fibrillation. All of these were big enough risk factors they reached statistical significance in our sample size. A lot of other risk factors like diabetes, being a smoker, having thickness of your ventricular walls were also risk factors for silent infarct. The effect size being a little smaller.
PALCA: I see. What - you know, you did these research MRIs, which I suspect is a more accurate or more complete kind of an MRI scan than you would get in your doctor's office. But is there going to come a time when people will be routinely screened using and MRI to see if they had one of these silent strokes?
Dr. SESHADRI: Well, still as, the previous caller point out, we already know that these are risk factors. The risk factors we've related to the silent stroke, for clinical stroke, as well. And to answer your question, certainly the time is not there now. But if we were to do a research and show that having this additional information, say, persuaded people to address their risk factors more aggressively. Then, you know, maybe that would. If - at this present time I would certainly not recommend that people go out and have an MRI. On the other hand, if you have an MRI for some other reason because say, you have a headache or you were in a minor car accident and somebody thinks you should have an MRI, and you do see a silent infarct, that would mean your doctor should screen even more aggressively for these stroke risk factors. because you're at higher risk of developing a clinical stroke.
PALCA: I got it. Well, thank you very much for sketching out these results, Dr. Seshadri.
Dr. SESHADRI: My pleasure.
PALCA: Sudha Seshadri is the investigator with the Framingham Heart Study and associate professor in the Department of Neurology at Boston University School of Medicine. Now, if you're like me and you've gotten older, you find yourself wondering what medical troubles you may be facing 10, or 20, or 30 years down the road.
I hope I make it that far. What if you could find out now how likely you were to have a problem, such as a stroke for example. Would you want to know, so you could take preventive action? Well, new research suggests that a series of simple neurological tests can help to determine whether someone is likely to have a stroke or some other disability, within as little as eight years. According to this study out in this week's edition of the Archives of Internal Medicine, the more neurological - we'll call them glitches - found in healthy adults today, the greater the risk of problems tomorrow. Knowing this, is it a possible to stop or even slow the onset of disability - before it starts?
Well, talking with me now is someone who may be answer - able to answer that question. Malaz Boustani is a research scientist at the Regenstrief Institute, a center scientist at the Indiana University for Aging Research, and an assistant professor of medicine in the Division of General Internal Medicine and Geriatrics at Indiana University in Indianapolis. He joins me today by phone from his office there. Welcome to the program, Dr. Boustani.
Dr. MALAZ BOUSTANI (Research Scientist, Regenstreif Institute): Thank you very much, and thanks for offering me this opportunity to communicate with your audience.
PALCA: OK. And if you'd like to join our conversation, the number is 800-989-8255. That's 800-989-TALK. What sorts of neurological deficits were you looking at that you found predictive?
Dr. BOUSTANI: I just want to clarify first that my paper was an editorial for an investigation.
PALCA: Right, right. I'm sorry. You were describing this, and commenting on another paper that was from a group in Italy, I think?
Dr. BOUSTANI: Exactly.
Dr. BOUSTANI: Correct. So if you want to spend the rest of your life in Italy, this will be very generalizable to you. It's not a bad idea.
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PALCA: OK, sorry. I'm heading off now. Talk to you later.
Dr. BOUSTANI: I think the Italian investigator are trying to exactly answer the question you raise. They picked up 500 people who have completely no evidence of obvious cognitive or functional disability.
They didn't have any history of stroke, they didn't have any history of Parkinson, they didn't have any history of dementia, Alzheimer disease, or even cognitive problems, and then they conducted a very simple routine neurological examination that usually every internist, geriatrician, or neurologist, or psychiatrist, do routinely in their office, as part of work up for a new patients, and they standardized the finding of the - this neurological examination, and trying to see if there was any kind of subtle neurological abnormality, example...
PALCA: Dr. Boustani, I'm going to interrupt you there just for a second...
Dr. BOUSTANI: Sure.
PALCA: Because we have to take a short break, and I know that you're going to finish describing this, but I'll stop you there, and we'll come back after we take a short break to let our stations tell us what we're doing for the rest of the day. Anyway, we'll be back with Science Friday, so don't go away.
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PALCA: This is Talk of The Nation from NPR News.
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JOE PALCA, host:
From NPR News, this is Talk of The Nation: Science Friday. I'm Joe Palca. We're talking this hour about the latest in stroke research and risk factors for stroke. We're talking with Dr. Malaz Boustani, who's at the University of Indiana School of Medicine, and he's the author of an editorial in the current issue of the Archives of Internal Medicine, that talks about a study that was done in Italy, talking about small changes in neurological features, I guess, on an examination that might predict later problems to come, and we had to stop Dr. Boustani. So maybe you could pick up with what kinds of things they were looking at, and what they were predictive of.
Dr. BOUSTANI: So, imagine that your doctor examined you neurologically, and found out that the right side of your shoulder - or your right shoulder is a little bit weaker than the left shoulder, but you never were told that had - you had a stroke, you don't have any other obvious disorder that explain the subtle differences or subtle weaknesses, or when you try to stand up, and the doctor trying to, you know, challenge your balance, and you were unstable, or you have a postural instability, or your handgrip was weaker on the left side more than the right side, or when you were sitting, resting, there was a little bit of tremor on one side of your body more than the other.
So these are very subtle, neurological abnormality, and you don't have complaint of it, you never complain, you didn't come over to the doctor complaining of these symptoms.
Dr. BOUSTANI: So the Italian put this subtle, neurological abnormality in a very, very simple way. They just simply counted how many of these signs were identified by the doctor, and that can be ranging from zero, all the way to 19, and then they tried to study, based on the number of these signs, can we tell the risk of death over the next eight years, or the risk of having a clinical stroke. So, this is the opposite of a, silent stoke.
Dr. BOUSTANI: A stroke that made you go to the hospital, and be evaluated and treated, and it's not this simple, silent, or transitional ischemic stroke. And also, they were looking to see if these subtle, neurological finding, can predict if you're going to have a decline in your day-to-day activity four years later, or decline in your memory, or your overall cognitive status.
Then, they adjust for your age, your gender, your other comorbid conditions, how you performed functionally and cognitively at baseline, and found out, depending on the number of these subtle, neurological abnormality, that your regular doctor could find, your risk of having a functional decline, memory decline, stroke, will increase in a very nonlinear way. Precisely...
PALCA: So - sorry, nonlinear meaning?
Dr. BOUSTANI: If maybe in the beginning when you have one or two, that's not going to be a big deal. But when you start having more than three signs
Dr. BOUSTANI: Then all of a sudden, your risk increase tremendously.
PALCA: Shoots up. And is there something you can do about that?
Dr. BOUSTANI: Right now, this is a very, very early stage of intervention. This is - will help up tremendously to allocate our resources and our efforts. So, with this study, gave us information about the highest risk population.
Those who are very, very vulnerable to develop these bad outcomes in the future, and now the next step will be a researcher or a clinical trialist who will take these vulnerable people, and enroll them in an intervene - prevention studies, give them certain pharmacological intervention or non-pharmacological intervention, and see if that will help reduce their future risk.
Dr. BOUSTANI: Or sometimes simply, a lot of my patients I seen in my clinic, they like to know their risk, even if there's no available prevention at this time.
Dr. BOUSTANI: It might motivate them more to do the healthy habit physically and mentally that they have to do anyway, but now with their highest risk of developing bad outcome in the future, they will be highly motivated to eat healthier, do some brain exercise, or walk 15 minutes three times a week.
PALCA: Sure. So this study tells you where you're going to get your most effective interventions, because you can tell the patients who might be at highest risk that they should...
Dr. BOUSTANI: Exactly.
PALCA: Really pay attention. All right, let's take a call now, and go to Marcia(ph) in Rochester, New York. Marcia, welcome to Science Friday.
MARCIA (Caller): Thank you. I think you've already answered my question, which was, is this akin to a TIA?
PALCA: Oh, do you mean the silent stroke?
MARCIA: Probably because they had not mentioned that before.
PALCA: Yeah, interesting. Well, maybe we can find out. Is a TIA one of the signs that they were looking for, or is that something different?
Dr. BOUSTANI: They actually...
PALCA: What is a TIA? Maybe you should tell people first what that is.
Dr. BOUSTANI. Sure. The TIA, it mean a transient ischemic attacks, it's simply when a person have signs of stroke, but lasts less than 24 hour. And they go away spontaneously. They might be recurrent in the future, but they never develop to a stroke, which with more than 24-hour deficits.
The authors of this study, they actually take into account the history of TIA or transient ischemic stroke, and after they adjust for that risk, the relationship between the subtle, neurological abnormality and the future risk of death, a clinical stroke, a functional or a cognitive decline continue to be the case.
PALCA: All right. Interesting. Thanks for that call. Let's take one more call now from Tina in Cedar Rapids, Iowa. Tina, welcome to Science Friday.
TINA (Caller): Hi. I had a stroke from a birth defect. I also have paroxysmal atrial tachycardia, which is hereditary. I was just wondering if that would be a risk for my mother and my grandfather, who both have the heart murmur.
TINA: But I know they probably would not have the MI, or the - you know, the AVM.
PALCA: Yeah, Dr. Boustani, maybe you can translate Tina's question, and answer it for us.
Dr. BOUSTANI: OK. I think what Tina's trying to figure out, the family history of a previous stroke or risk - high risk factor for stroke, and the future risk among other member of the family. This study - the Italian study - does not answer that questions at all, and from my own experience, the condition that you're suffering from, I do not think they will affect the probability of your other family member to have a stroke.
Ms. TINA: They're significantly older than I am. I was 23 when I had the stroke.
Dr. BOUSTANI: Yeah. So, I think that they will have their own risk factor independently of your medical story.
PALCA: OK, Tina. Thanks very much for that call. I'm afraid we've run out of time for this segment, but I'd like to thank Dr. Boustani for joining us today.
Dr. BOUSTANI: Thank you very much for the invitation.
PALCA: Dr. Malaz Boustani is a research scientist at the Regenstrief Institute, center scientist at the Indiana University Center for Aging, and assistant professor of medicine at Indiana University in Indianapolis. He had an article - an editorial on this week's Archives of Internal Medicine, describing an Italian study, looking at risk factors for stroke.