July 29, 2011
NIH Podcast Episode #0139
Balintfy: Welcome to episode 139 of NIH Research Radio with news about the ongoing medical research at the National Institutes of Health – the nation's medical research agency. I'm your host Joe Balintfy, and coming up in this episode research using math to address childhood obesity…
“Models can help us understand large complex systems, and childhood obesity certainly has a lot of different parts of it being a system.”
…and about math, how some children have difficulty estimating numbers, plus post traumatic stress disorder. But first, this news update. Here’s Craig Fritz.
Fritz: The National Institutes of Health, has some advice for helping older people avoid heat-related illnesses, known collectively as hyperthermia. Older people can face risks related to hot weather. As people age, their bodies lose some ability to adapt to heat. They may have medical conditions that are worsened by heat. And their medications could reduce their ability to respond to heat. Hyperthermia occurs when the body overheats. Conditions involving hyperthermia have different names, including heat stroke, heat fatigue, heat cramps and heat exhaustion. Heat stroke is an advanced form of hyperthermia that occurs when the body is overwhelmed by heat and unable to control its temperature. Someone with heat stroke may have a strong rapid pulse, lack of sweating, dry flushed skin, faintness, staggering and mental status changes such as confusion, combativeness, disorientation or even coma. Seek immediate medical attention for a person with any of these symptoms, especially an older adult. If you suspect that someone is suffering from a heat-related illness: move them into an air conditioned or other cool place; urge them to lie down and rest; remove or loosen tight-fitting or heavy clothing; encourage them to drink water or juices if they are able to drink without choking, but avoid alcohol and caffeine; apply cold water, ice packs or cold wet cloths to the skin; get medical assistance as soon as possible. For more information on hyperthermia, visit www.nia.nih.gov.
A team lead by NIH researchers has identified the genetic mutation that causes proteus syndrome, a rare disorder in which tissue and bone grows massively out of proportion. Proteus syndrome gained wide public attention in 1980, through the movie “The Elephant Man,” about a 19th century Englishman whom experts believe may have suffered from the disease. Researchers found that a small mutation in a specific gene that activates the sporadic tissue growth characteristic of proteus syndrome. There are fewer than 500 known cases of the disease in the developed world. Unlike inherited disease-causing mutations, the gene variant that triggers proteus occurs spontaneously in each affected individual during embryonic development. The severity of the disease depends on the timing during development that the genetic mistake occurs in a single cell and in which part of the developing organism. Only the cells that descend from the cell with the original gene mutation display the hallmarks of the disease, leaving the individual with a mixture of normal and mutated cells. The affected newborn appears normal, but symptoms arise in the child’s first two years. The mutation in the gene alters the ability of affected cells to regulate their own growth, leading some parts of the patient’s body to grow to abnormal and even enormous sizes, while other parts of the body remain normal. The irregular overgrowth worsens with age and increases the susceptibility to tumors.
For this NIH news update – I’m Craig Fritz
Balintfy: News updates are compiled from information at www.nih.gov/news. Coming up later, estimating numbers and PTSD but research on childhood obesity is next.
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Childhood obesity research
Balintfy: When researchers and scientists examine health problems, there are a lot of tools to use – we talked recently about how Google Maps can be a tool to analyze and examine brain imaging data. Some tools are more common, like a simple stethoscope or heart monitor. But others aren’t quite so tangible, like mathematical modeling and simulation. None the less, these systems science approaches can be used to address questions about health. Recently a symposium at NIH looked at addressing childhood obesity, which we all know is a major health problem. Dr. Laura Brennan is chief executive officer of Transtria and explains what it will take to undo the problem of childhood obesity.
Brennan: Well, I think it’s mostly going to take coordinated efforts at the national state and local levels to create change and that coordination is going to need to happen across both research and practice and policy efforts. So we need to take a look at the evidence and building the evidence around what is working and what’s not working, and we need to also work with policy makers and practitioners to get the things that are working implemented on the ground and in ways that engage communities and create sustainable change.
Balintfy: And why focus on national, state and local policies to address obesity rather than letting the parents decide what their children should eat?
Brennan: The main reason is that we need to create opportunities for parents and children to make healthy choices. In a lot of circumstances, kids and parents don’t have access to healthy foods or places to be active in order to reduce childhood obesity. So we need to make sure that there’s grocery stores in neighborhoods, make sure that there’s farmers’ markets and other places to purchase healthy foods, make sure that there’s parks and recreation centers, that it’s safe for kids to walk to school, that the traffic safety and interpersonal safety issues get addressed.
And also in schools, we need to ensure that kids have opportunities to make healthy choices, that we have physical education in schools, that we have recess policies that encourage kids to be active, and also healthy foods in school. So we need to create those opportunities for people to make the healthy choices.
Balintfy: Dr. Brennan is also an assistant professor in the department of community health at the Saint Louis University’s School of Public Health. She has basically described – as she did in the symposium – the background problem, the complexity of childhood obesity. To the get into what a “system dynamics” model is and how building one for childhood obesity can help guide policy decisions, here’s panelist Dr. Peter Hovmand at the Brown School of Social Work at Washington University at St. Louis.
Hovmand: So we use models all the time to try to understand systems. Models can be helpful for a number of reasons but often when systems get really complex. So Laura has talked about how you have schools and parents involved, you also have communities, you have availability of grocery stores, and all of that forms a pretty complex system. So if you’re going to try to figure out what kind of policies to implement, how much they might cost, what kind of impact, it gets pretty complicated pretty quickly.
Models help us see that and then system dynamic models in particular help us understand where some of the feedbacks might be in the system, where things that you implement initially look good and they’re harder to implement later, or things where you can start to build up and let things grow in terms of scaling up interventions. And then we use system dynamic models in particular to understand the feedback loops, and then we use computer simulation to try to estimate what the effects might be from various kinds of policies, as well as thinking about the costs and what might be the overall impact on the system.
Balintfy: As a panelist, Dr. Hovmand showcased mathematical models that are under development as part of the Comparative Modeling for Child Obesity Policy Network, which is part of the Envision Network of mathematical and statistical modeling teams under the National Collaborative on Childhood Obesity Research. Other than the Envision Network, Dr. Hovmand explains what other kinds of modeling are featured in the Network, and how using more than one modeling approach will help inform policy decisions about childhood obesity.
Hovmand: So the comparative modeling network, in addition to system dynamic models, has also agent-based models where instead of modeling the system dynamics, you model the whole system at an aggregate level. You’re modeling the actual individuals and how they’re making various kinds of choices.
So there’s several teams that are using agent-based modeling, then there are also some teams that are using Markov models which are statistical models and then also some social network analysis. And to a great extent actually, teams are somewhat familiar with the other methods and there are some examples of where teams are actually using more than one method.
Probably the big advantage of having a network over what you could do in an individual study is that you can build off the strengths of various methods so different teams can come collaborate and compare the results using two different methods and then see what the potential differences and similarities might be.
So for policy makers, that’s really important. It’s like a weather model where if you only had one weather model, you wouldn’t really know what actually might be happening; but what you do in weather simulation models is you have multiple models, and if you start to see the results converging, even if they had different assumptions, different methods, different teams, you might as a policy maker have a little bit more confidence in what it is that’s being recommended; and you really can only get that though having a network like that being supported by Envision.
Balintfy: For more information about mathematical modeling and the symposium where Drs. Brennan and Hovmand presented, visit videocast.nih.gov/launch.asp?16756.
Difficulty estimating quantity linked to math learning disability
Balintfy: Now to learning about math. Researchers have discovered that in children who have a math learning disability, the ability to estimate quantities that usually exists from birth is impaired. Wally Akinso has this report.
Akinso: Researchers have discovered that the ability to estimate quantities is impaired in children who have a math learning disability.
Koepke: The medical term for math learning disability is dyscalculia.
Akinso: Dr. Kathy Mann Koepke is a staff scientist at the National Institutes of Health.
Koepke: Usually we use this term to refer to a broad range of mathematical difficulties in learning and performance, but these difficulties can not be attributed to inadequate or poor instruction. So there is something besides poor schooling.
Akinso: In a recent study researchers compared children's ability to estimate quantity with their level of mathematics achievement. The study was conducted by Dr. Michèle Mazzocco and colleagues at the Kennedy Krieger Institute and Johns Hopkins University in Baltimore.
Koepke: Dr. Mazzocco and her colleagues used the computer screen to quickly, very briefly for 200 milliseconds, flash colored dots of different sizes and colors, and groupings to measure the participant's Weber fractions or their ability to number discriminate.
Akinso: In the second series, 9 to 15 dots of one color appeared, and the students were asked to say how many dots they saw. The researchers gave 71 ninth graders these two series of tests designed to measure their capability. Dr. Koepke explains that the children were broken up into four groups based on their 9th grade achievement scores.
Koepke: There was the math learning disabled group, which are those children whose math achievement score was at the 10th percentile or less meaning they where at the bottom of achievement. Low math achieving group, they scored between the 11th and 25th percentile on the math achievement score. A typical mathematics achievement grouping scoring between the 25th and 95th percentiles, and then there was the fourth group which is of course the smallest group along side the math disabled group of high achievement or those children who had achievement scores at the 95th percentile or better.
Akinso: Dr. Koepke says the findings suggest that students may struggle with math for very different reasons.
Koepke: Children with math learning disability had significantly higher Weber scores or number discrimination and number identification or number of mapping scores.
Akinso: According to Dr. Koepke, these findings suggest that the problems with the approximate number system underlie math difficulties for children with dyscalculia compared to all the other groups. The researchers point out that approximately 10 percent of school-age children have persistent and significant difficulties with math and many more fail to achieve basic levels of mathematics achievement. They add that research to identify the factors underlying math difficulties may lead to new ways of identifying those at risk, and developing the means to help them. For more information, visit www.nichd.nih.gov. This is Wally Akinso at the NIH, Bethesda, Maryland.
Balintfy: Coming up, a discussion about post traumatic stress disorder. That’s next on NIH Research Radio.
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Post Traumatic Stress Disorder
Balintfy: Through research, NIH is transforming our understanding of fear related disorders like post traumatic stress disorder or PTSD. New insights about how memories are formed, how they are accessed and when they are vulnerable to modification for their association with strong, fear-related emotional and physiological reactions, is paving the way for new developments. Prevention of PTSD is becoming a realistic goal – experts predict that we can envision a day in the not-too-distant future when a combat medic or emergency room physician performs a series of assessments with survivors of combat, motor vehicle accidents, physical or sexual assaults and if the assessments indicate high risk, initiates early treatment to prevent a cascade of neurobiological processes leading to PTSD and related functional concerns. NIH and its National Institute on Mental Health are making investments to acquire the knowledge needed to realize this goal. Dr. Ferris Tuma is Chief at the Traumatic Stress Disorders Research Program. He was recently interviewed by Dr. Vivian Pinn for the Pinnpoint on Women’s Health podcast. Here are some excerpts from that interview starting with what exactly is PTSD.
Tuma: So, PTSD or posttraumatic stress disorder is an anxiety disorder that can develop after somebody experiences something or witnessing something very frightening. This can usually result in feelings of intense of fear, horror, or helplessness.
The hallmark symptoms of the disorder have to do with beyond those initial reactions that somebody has, re-experiencing. So both in terms of they might be dreams or nightmares that people would have about their experience, but also during the day having thoughts about what happened to them that they just can't turn off. Another hallmark symptom has to do with avoidance and this is, as it sounds, people try to literally avoid anything that would remind them of where they were or what happened, also avoiding talking about it. The third big category of symptoms has to do with arousal. So, this creates a very heightened sense of maybe something bad is going to happen. Somebody is easily startled, they're jumpy, they have difficulty concentrating and sleeping.
The diagnosis of the disorder can be made after somebody has these experiences that last for at least a month after their traumatic experience.
I say that PTSD can happen because it may be useful to keep in mind that the vast majority of people who experience something traumatic even very life threatening and dangerous may have these initial reactions of helplessness, anger, horror, or difficulty sleeping, but they get better.
The story of PTSD is really the exception to the rule. Most of us get better when something bad happens. For some people, these feelings of anxiety and fear, anger, replaying an event in their mind over and over again doesn't go away and this is where it begins to interfere with their ability to function and the diagnosis of the disorder can be made.
We know from good research now that the prevalence of PTSD, in the general population so I'm not looking at any particular groups, is around 7% for somebody's lifetime, okay. What this means is that in any given year, about 7 million Americans or 3.5% of the population in the United States can be diagnosed with the disorder. And we also know that about a third of these cases are classified as quite severe, meaning they're really unable to carry on normal activities and to function in their regular world.
Balintfy: What is research telling us about how PTSD works?
Tuma: Probably the most exciting and sort of revolutionary research that's being undertaken now has to do with how we create memories, very strong memories. You know, once upon a time it was thought that if something happened to you, the memory is created, it's laid down, and it's there forever. We now know through pretty good research that it's actually a little bit more complicated. That a memory that we might have from five or ten years ago is actually not the memory of that event five or ten years ago, it's a conglomeration of each time we’ve re-remembered that, if you will, or retrieved it and what's happened as we retrieve it.
Balintfy: Does this help in terms of potential treatments for PTSD?
Tuma: We used to think of, as I mentioned, that memory being fixed. We now know that we can tweak it, we can go in adjust it and I don't mean change somebody's memory to the point where they don't remember it or that the event didn't happen, but the association they make with it. So for example, I was in that motor vehicle accident and I keep having these feelings of it's happening all over again or it's going to happen all over again if I get in a car and there's going to be screeching tires and there's going to people hurt, that's a very fearful memory and association.
We now know that there are opportunities to attack that. So when somebody talks about it with their therapist, over time with equipping, giving that person some skills to manage their immediate reactions, you can actually -- the term that you use is extinction, which is to replace that very fearful, anxious conclusion that they draw in their mind about the event with one that's less fearful and less anxious. Meaning I'm remembering what happened, but I know I'm going to walk away from it. I know that it's not happening again. You know, the analogy in natural disasters is the wind blows, but it doesn't mean there's a hurricane.
Balintfy: What would you emphasize regarding PTSD?
Tuma: I guess the main point is this is not a condition where somebody has to struggle alone. Very, very difficult to come out of your shell and seek help for this condition primarily because one of the hallmark symptoms, I mentioned, avoidance, keeps people from wanting to talk about it. These therapies are not easy, they're work. The patient has to be in a position where they want to get better and so it's hard work; but with support, one does not have to live with these sort of haunting experiences that continue to impact their life in a negative way.
So reach out, either directly with a care provider or do some research on your own to resources that are available through the NIH and other places to get help.
Balintfy: Dr. Tuma mentions a 24-hour suicide prevention hotline, 1-800-273-TALK or 1-800-273-8255, and other resources at www.nimh.nih.gov. To hear the entire interview with Dr. Tuma, listen to the Pinnpoint on Women’s Health podcast at the Office of Research on Women’s Health website: orwh.od.nih.gov.
And that’s it for this episode of NIH Research Radio. Please join us again on Friday, August 12 when our next edition will be available. I'm your host, Joe Balintfy. Thanks for listening.
Announcer: NIH Research Radio is a presentation of the NIH Radio News Service, part of the News Media Branch, Office of Communications and Public Liaison in the Office of the Director at the National Institutes of Health in Bethesda, Maryland, an agency of the US Department of Health and Human Services.