Aug 6, 2019
Dr. Kim Kirkpatrick is a University Distinguished Professor of Psychological Sciences here at K-State where she is the director of the Cognitive and Neurobiological Approaches to Plasticity Center (CNAP) and leads research at the Reward, Timing, and Decision Lab. The main focus of her research is the role of timing and reward processes in determining impulsive and risky choice in rats. This was a very interesting conversation where we discuss the role of diet, specifically those containing foods high in certain types of fats or sugars, in promoting impulsive behavior that may be linked to obesity. There are all kinds of implications for this type of work in our personal lives as well as governmental policy and we try to dig into all of that. A fascinating topic that surely many of you will enjoy!
For more about Dr. Kirkpatrick and the projects she is working on check out: https://www.k-state.edu/psych/research/kirkpatrick/
Transcript:
Diet, Impulsivity, and Obesity: Does What We Eat, Influence How We Behave? – Dr. Kim Kirkpatrick – Psychological Sciences
Something to Chew On is a podcast devoted to the exploration and discussion of global food systems. It's produced by the Office of Research Development at Kansas State University. I'm Jay Weeks PhD candidate in the Department of Agronomy. My co host is Scott Tanona, an Associate Professor in the Department of Philosophy who specializes in the philosophy of science. Do you ever wonder sometimes why you do the things that you do? Or why, when there seems to be an obvious rational route to a specific goal, some people repeatedly undermine their own desires and best intentions. The current scientific literature and decision making is extensive and far from complete. But what is becoming increasingly apparent is that in some ways, we may be in less direct control than we might want to believe. Our guest today is Dr. Kim Kirkpatrick. Kim is a University Distinguished Professor of Psychological Sciences here at K State, where she is the director at the cognitive and neurobiological approaches to plasticity center, and leads research at the reward timing and decision lab. The main focus of our research is the role of timing and reward processes in determining impulsive and risky choice in rats. This was a really interesting conversation where we discussed the role of diet, specifically those high on certain types of fats, or sugars, and promoting impulsive behavior that may be linked to obesity. There were all kinds of implications for this type of work on our personal lives, as well as governmental policy. And we tried to dig into all of that. Definitely, it was a fascinating topic that I'm sure many of you will enjoy. So we now bring you Dr. Kim Kirkpatrick. Dr. Kim Kirkpatrick, welcome to the podcast.
Thank you, it's good to be with you.
So I've been pretty excited to have this conversation. I've been looking forward to it ever since we got into contact. And before we get into what your lab does, and your research and all of that, we usually like to get a little bit of background information. So if you wouldn't mind, would you tell us a little bit about yourself?
Yeah, so I'm a professor in the Department of Psychological Sciences, I also direct a center of Biomedical Research Excellence over there, the C nap center, and I've been at K State since 2008. Before that, I actually taught and did research for eight years at the University of New York in the UK. And then going back a little bit further, I did my graduate training at the University of Iowa, and my postdoctoral training at Brown University.
So what got you into psychology?
You know, I actually started off, as at Iowa State University, and I went there for engineering. And I took a general psychology course, and it was taught by a neuroscientist, and it just lit me up, I loved it. And I changed my major, like, almost right away, was illuminating to see, you know, explanations for things going on around you why people behave the way they do, or what, why, and it was really the brain, which is like, I just seem so fascinating. And so, so much that we didn't know about it. It just sort of seemed like this frontier that I just wanted to, like, get into.
How would you say the fields change, like since then to now?
We know a whole lot more. So I think that's good. And I hope I have made my own little bit of contribution there. I definitely, I think that there's a lot more public awareness of neuroscience now maybe helped a little by Big Bang Theory. And then brain health, I think is really become a really big issue. I think this understanding that we need to not just look after, you know, things like our heart, but we need to also really think about our the aging of our brain as saying something that's very near and dear to me for our research programs. I think about brain health and how, like things that we eat and do kind of affect our brains.
We have more information certainly is the general overall quality or veracity of that information. Higher or lower, we seem to get a lot of population of social media sites with information that's potentially spurious.
Yeah, I mean, I think that, you know, I mean, I'm sure you guys are aware, the replication crisis, I think that has shone a spotlight on some issues with all sciences. And I think there are some things that came out of that that, you know, have made people aware that we really need to think about the robustness of our methods. I think neuroscience certainly has advanced to Having much more elegant techniques that allow us to get at functioning specific cell types and networks. And in that sense, I think has been very good. But oftentimes, as we start to really drill down and become more specific, we also begin to lose some of the power to really detect effects. And so I think there's always a trade off between specificity versus whether you can really get the the power of you need, I mean, because if you're getting really specific, you might now get down to where you're dealing with five neurons, and then are you gonna really be able to figure out what those five neurons do? Yeah.
For the listeners who don't know, what is the replication crisis? And why was it? Why is that important?
So really, it refers to the fact that some of the results that have been reported, even ones that are like in textbooks, haven't really bore up to being able to be replicated when others went and tried to, you know, do the research very similarly to how it was originally done. And I think what really kind of came out of it was this recognition that some of its because of the way we do our statistics, and too much of a focus on P values and trying to just get over a certain line, and not enough of a focus on effect sizes. And it turns out a lot of these things that don't replicate very well, are really small effects. And so they're just probably, you know, spurious. And something to do with the group that was, yeah, it could be something with the group that was tested, or whether presuming.
Something is a replication when in fact, is not a replication. It's not a true statistical replicant?
Sure.
So well, so and this is it just for everybody? You know, for people who are listening, it said, not to Psychology and Social Sciences. You know, a lot of other areas, a lot of medicine and cancer research, right?
Oh, over pharmacology is a really big one. drug development research was a huge one, I think the one thing is really kind of shown us is that you do really need to have robust designs, you need to have good sample sizes. And also it turns out that within subjects research is much more replicable. So if you, you look at an individual's behavior, relative their own baseline performance, that's much more replicable than if you're looking at comparing two individuals.
Good. And and some of the responses to this, I mean, so, you know, there's there's been these increased efforts to do more replication, the incentive structures for scientists to do these are not great, right? So this is, this is a hard thing, we don't actually do a lot of just like, let's try to do exactly the same thing, right. But, but some of the response to this has been that looks, we've got some maybe some things about our statistics that we need to worry about. But some of it is just about the transferability. Right, from one area to another, right? So you do a study on, you know, group of undergraduate students at your institution. And then you say there's this general phenomenon, right, but doesn't necessarily apply somewhere else. Because like, people are so complex, right? So just, I don't want to push you too much on this stuff. But what's your main thought? I mean, how much of this is like the things didn't replicate? Because as John just said, they were actually looking at like a different population, or there's something different going on, and how much of it was, things didn't replicate? Because, you know, we were looking at such a small little effect that maybe we thought we found something that wasn't there.
I think there probably are some of that, too. There's all effects have boundary conditions, right. And that can affect replication if people go outside of those boundary conditions. One thing we do a lot in my research program is we build a nested replication to a lot of our designs. So that way, if we get a result, that seems like funny, like not what we expected, we can at least look at the nested replication conditions. So nested replication. And replication is where you maybe have like one or two of the conditions within your study, that are things that you already have done before. So it's actually like provides a way to connect together, like if you do two experiments, and the second one, you now include at least like one condition from the previous experiment. And then there's actually statistics you can use it's kind of Bayesian statistics where you can use the first experiment as priors for the second one. And you can actually do tests on like, you know, how likely is that effect is thing going to replicate if you do it again and again. So I think that's one really good way forward. Whenever I kind of write my grant proposals and I have to talk about robustness and replicability. I really call upon nessa replication as a real strength.
So what kind of work is your lab doing?
Yeah, so I mean, we were really interested in impulsivity, which is when you aren't really able to wait in order to maybe get a better outcome. So we specifically study and if you guys know the marshmallow test, yeah, it's very well now. Explain it. Yeah, steady decisions, kind of like the marshmallow test where, you know, this was done in kids where they kind of had a choice between you could get one marshmallow now, or you could wait 15 minutes, and then you can have two. And for some of the kids could wait, and some didn't do so well. But what made it so famous and my philosophers know about the marshmallow, is it when they went back and looked at these four year old kids, when they were teenagers, they actually found that the kids who could wait had higher LSAT scores, they actually were performing better on a lot of metrics of their, like, social, you know, abilities, and their, you know, abilities to like, deal with, you know, challenges and things of that sort. And they really funny enough, they actually went back and looked at these kids when they were, they're in their 30s. And they actually found that the kids who waited for the two marshmallows had lower BMI. And that's kind of interesting, when you think the kids who waited for the two marshmallows actually are thinner later. Yeah. And what that tells us is, it's not really about the marshmallows, but it's about the self control, you need to be able to wait for the marshmallows. So I mean, I think this is really fascinates me that so famous that this test, you do just one time with a kid, when they're four actually predicts all of these things like later in life, even we into well into adulthood.
That's interesting, because that crosses metabolic changes across brain development stages.
Yeah, and all different kinds of like SES, and lifestyle, and just, I mean, all different kinds of things that are and this does like to be a well replicated effect.
So is this did you get interested in this early on in your psychology career? Or is it something you came to after some period of time.
I kind of migrated there, but it was kind of my research program, you know, just as it does, you tend to kind of build and progress. And then I would also say that a lot of my research is student driven. And so one of my students was actually the first person who kind of started doing impulsivity research in my lab. And she found some really exciting things. And we just kind of built from there, we kind of continued doing it. I always like to let my students take me interesting places.
Interesting. And how do you decide which ones you've not? Which student but which? Which research project? gets to move forward with these undergraduate students?
This is actually a PhD. Okay. It was her dissertation that really get that question where we're going. Yeah, we do have undergraduates can do some interesting things, too, though.
So how are you testing impulsivity? Is this more marshmallow tests or what's going on?
Well, we have some work, most of our work is in rats. But we do also do some work in people. So in our rats, what we do is, they're actually in a special box where we can give them these levers that they can press. And we have these little food magazines are called that actually let us deliver automatically with the computer, different numbers of food pellets. These aren't nearly as tasty as marshmallows, that I go around by tasting. But so the rat can choose like, does it want to get food, put one one food pellets and maybe has to wait five seconds? Or it can be for, say, 20 seconds? And it could get to? So it's the same kind of question, right? It's just asked in a different way. Now, of course, the rats don't really know what those contingency are, they have to learn them through pressing and getting things. And we also, don't just ask them once, we asked them hundreds of times, and we can change them out and change the delays. And then people were actually doing something that's very similar to what we do in the rats. We have actually a food dispenser, very much like the rats, it dispenses mini m&ms. And people get a question on the computer screen, it's literally says like, you know, one m&m In five seconds or two m&ms in 20 seconds. And then they pick and then they have to wait, and then the m&ms Come out? And yeah. And they I mean, their behavior actually looks very similar, though, between the humans and the rats.
Is there? Is there an assumption that everybody's gonna want more food or more m&ms? Or is there you know, what's the utility function here?
Something really interesting. There we go. Because some people just want just won't.
Yeah, and some just want like, just one.
And so we'll just pick the five and it doesn't matter, no matter what, but always pick like the five, which is the biggest one we offer. But we actually found that people, we've done some work looking at how diet, you know, kind of predicts what people do on this task. And we found that individuals who eat very low sugar diets actually really only wanted the small choice m&m, no matter what. So I thought that was interesting maybe reflects them like kind of having such a really high level of self control or possibly just that they've developed a preference where it's like, I just don't eat much sugar, so I'm not gonna walk. Right.
And yeah, cuz, yeah, as we want to find out what you're doing with all this, but I think one of the basic questions are about sort of, if you're measuring impulsivity, right? It's kind of an assumption that, like, Oh, if you wait for more, that makes more sense, right? You know that you're, you've got more self control in that sense, right. But yeah, but yeah, there's a lot of factors which you control for, right, by looking to sort of see what their other interests are.
Yeah. And I thought it was really interesting that people on the low sugar diet, I mean, they're actually exhibiting self control, but they're doing it a different way, from what we think about what the marshmallow kids, they're not really necessarily doing it by being willing to wait for maybe a longer term outcome of like, I'm going to fit into that dress on Saturday, right? Rather, what they're doing is they're, they're regulating their amount preferences, saying, I'm just gonna prefer to eat really small amounts of that food type.
Probably just the same thing in terms of salt, or people are on low salt diets to see the same effect.
Yeah. So I really want to dig deeper, because we just found this in a study we did pretty recently, I would like to dig deeper and try to understand some of the strategies that people engage in, saying self control is certainly one that we know is really important, but there may be other, maybe even some decision biases that people develop like or heuristics that people develop, where that just allows them to say just almost be automatic in those decisions, where they just say, I always just pick the small one or something.
I might explain what he meant by heuristics.
Oh, yes. So heuristic is really just kind of like a rule that you can use, that helps you be able to make decisions more or less automatically, you don't really have to think too much about them, you just, you just do it without thinking. And that can be really beneficial. If people can establish those if they're wanting to like change their health, because then they're just doing those behaviors automatically, almost habitually, rather than having to actively work at them.
And is it true that actually sort of a lot of how we live our life is really just like this, we kind of like develop these rules, and we kind of tend to just follow them, right? We're not every day processing. Each decision we make, right? In a way we're like, alright, which is going to be better for me, right?
Yeah. Yeah, there's actually, so I don't know if you've heard of Daniel Kahneman. Yeah. So he's got the system one versus system two, and the system one are these biases, heuristics and just automatic processes, they guide the majority of our behavior. But then we do have the ability to engage. So this more complex systems, but people are actually very lazy cognitively. They actually would much prefer to engage system one and only use system two, when you're really forced to…
right. And it's not like that's a decision either, right? It's just kind of what happens, right?
I mean, I think it's because system two is really like it's it's labor intensive, it actually uses a lot of brain fuel, if you will, to engage system to
So these actually different physical systems, are they kind of, you know, how do you think about these as when you say, system?
I think there are bound to be different brain networks, although I'm sure there's overlap. But I think the thinking of it as a system as more a way to just distinguish that, you know, sort of psychological processes.
Yeah. Yeah. And when you say there's biases in system one, this is because they're automatic. And they, they work well, for a lot of circumstances. But under other circumstances, they like send us the wrong way. Right? Is there like some standard examples of those?
Yeah, well, even just the example, I was going back to my low sugar people, a choose small bias, maybe it's really helping them with their dieting, but it maybe won't work so great if they're like making decisions about money.
So some of the work you're doing in your lab is looking at what dictates who who has these biases and things right, and you know, whether or not you're you're genetically born with it, or whether or not it's your diet that's affecting this. And so what's going on there?
Yeah, so we're, we are looking at those factors. And we are also interested in whether we can change decision making. So we were really interested in dietary factors. That's one of the big areas we look at, we do also look at individual differences, to try to like it, you know, what kinds of variables might just, you know, predict how people are going to choose in different situations. And then we're also developing interventions. My current NIH grant is actually all about developing these interventions where we're trying to train self control. We've actually gotten a great success with this with our rats, and we are currently working on trying to translate it with our humans. I think one advantage we have with the rats is that they live with us. And so we can just, you know, really train and train and train them and they become really self like happily self control, not over self control, but like happy level of self control. And it does seem to provide then some resistance to problem behaviors that emerge from impulsivity. But we haven't quite got it working in people yet.
Oh, well, so how does it working rats, what do you do to train them?
We actually give them experience where they have to just work at learning the delays that they experienced in the task. So we might just give them like 10 days where they just get the 22nd delay that they'll later have to choose about. So they have no choice there is that they don't have a choice. So it's forced exposure to us the kind of delays that they're going to later have to make choices about, I think one thing that happens is they really learn the delay. Like they learn them better than they do when they're in their choice environment.
I was gonna ask you whether or not there are differences in populations for time length discrimination.
Yes, that's actually one of the variables we look at, we found that poor time discrimination is a predictor of impulsivity. And that's true in people is true in our rats and ADHD, is, yeah, it's associated with poor time discrimination and heighten impulsivity. Yeah, so that's one of the factors we look at. And we think they're time discrimination does get better when we give them this training. And then we also think that they just learn how to wait. Better. And so we have that factor as well. But we have been very successful in training the self control rituals who that means.
Are there dietary factors and things that control the ability to maintain self control? So you know, not every person is able to, to have discipline, right? Or to the same degree, what are, what are some of the factors that might impact that?
We've looked at high fat, high processed fat, I should say, so Christgau, and high sugar diets in our rats. One thing that's very nice in rats, is that you can control their dietary history. So we can really say that is really the diet, because oftentimes, diet actually is confounded with a lot of other things in people. But associated with all kinds of other things that might like low SES, and you know, even just like where you live, there are also notable wires, if people aren't good at reporting their diets, even when they mean to, you know, and then plenty of people try to hide what they eat, but, but in our rats, we can actually, you know, control this experimentally. And we found that both high fat and high sugar diets, if they get a few weeks of exposure to them, make them more impulsive. And then we find even, so they were on the diet for several weeks. And then when we remove them, and give them some time to like, just get back to normal, their weights dropped back down to normal. And then we retested them, we actually found that in a subset of the high fat rats, they actually still remained impulsive. But the remaining high fat rats and the highest high sugar exposed rats actually recovered and looked normal. So we think that fats particularly seem to reproducing major, like pervasive and probably long lasting changes in the brain in the brain and make you more impulsive. Yeah, at least for the rats. Yeah, so fats are very inflammatory. So these processed fats that I'm referring to, so we think there's probably neuro inflammation that's causing damage, and that's long lasting.
Like, what's the difference when you're talking about process fat? So like, do you haven't tested other things? But do you have a hypothesis about what's the difference between the process fats like why? Why the more inflammatory right and might be affecting the brain more than other fats?
Yeah, it seems that the, the processed fats, I'm not, I'm not sure exactly what the reactions are. But they actually damage the blood brain barrier, which is the very, that kind of keeps things out of the brain that are designed not to hurt our brains. And then that allows it become more porous. And then it means that the fats themselves can get through as well as a lot of other things that can lead to inflammatory processes.
Wow. And so what's in the category of processed fats? Or Christgau? You said, but what other things? I don't know anything about fats?
Yeah, so it'd be really any, like, for example, your hydrogenated vegetable oil would be another example. So anything that's really being you know, like, processed through this, like a natural fat like butter would be a natural fats, but anything that's being kind of processed to change its constitution, and then saturated fat, I think is a really key element too.
So does this create sort of a like a vicious cycle of impulsivity, then, you know, if you're on a poor diet, and then you aren't able to control yourself, you eat further poor diet. So you just kind of spiraled down down the hole, then?
Yeah, I think that's exactly what happens. And we've actually been able to really kind of chart that in our rats and see that vicious cycle development happens so and I think if you kind of think about people who are living and like what are called obesogenic environments, and if you've kind of come across that term, but it's their environments really promote obesity because there's a lot of fat food fatty foods like you know, your lots of McDonald's and other kinds of fast food rest John's in the area, that would be a really big problem when you think about it, because people are probably more likely to eat those foods because they're readily available and cheap. And then as they eat those foods is going to undermine their self control. And it means that they can't just drive past those restaurants anymore, they're going to be tempted to want to go in.
Is there any indication that this affects children, or adults more so or less so if a child has a high fat diet early on, does that, you know, promote this behavior more as an adult?
I think that in terms of the brain health effects, almost certainly are going to be worse in a developing brain. Because you could actually alter the trajectory of development if you're producing neuro inflammation during that time. So I would expect that with children, if you are producing this kind of high level neural inflammation, you would really see different developmental trajectory in the brain, and probably much more likely to have persistent long term effects.
So it's also suggested that perhaps parents or other professionals are really taking the wrong approach when they're trying to deal with young obese individuals to try to get them to change their behavior. If they're doing things that are still allowing a diet that's allowing more impulsivity.
Yeah. Oh, yeah, I think changing the diet is probably the first step. And then maybe some self control training would be another really good thing, we've actually started doing a little bit of work with healthy hawks, which is at the University of Kansas, their childhood obesity treatment program. And one of the things that they found is that impulsivity is actually the big predictor of dropout from the program, and also from like failure to go along with the exercise and the dietary requirements, which, you know, not surprising, right? So we're kind of working to see if we can develop our interventions, we've done in our bats into an app that the kids can maybe use to practice their self control, I think maybe we could do some scaffolding where we could get their self control, maybe looking a little better than they might be able to stick with the diet and the exercise and might be able to stick with the program.
So I wanted to follow up earlier about that. But so you're talking about training the rats, right? Not as much success in humans yet, but you don't have as much control, what have you. What have you been doing? What have you seen for training people to be less impulsive?
Yeah, I mean, like I said, it's very early stages. But there is some, there's a little bit of literature in kids. It's a little bit older, actually. But we're individuals did this kind of delay exposure training, same sort of thing, the same sort of thing. And they found, at least in the short run, they were able to get improvements and self control. In our rats, we've actually found that our intervention effects lasted when we retested them nine months later, which is I think, 15 human years, I think so we actually have a technique that's not just strong in terms of its effect size, but also really long lasting.
What are those interventions?
Sorry, where we just give them that first exposure to the delays repeatedly, and then later give them choices between the delays of the good.
So what would this look like in humans is this sort of thing like, right? Oh, I'm hungry, right? Now, let me let me like, set up my lunch, but put it off to the side for a little bit before you did, or like things just like spend a bunch of time just doing that kind of thing are
We actually with the healthy hawks, we're developing a game that the kids play, it's a type of space invaders like game. But what they have to do is like they press a button to fire a shot at the ship, but then they have to wait a certain amount of time before their missile recharges. And they can fire again, and we don't tell them how much they have to we. So they have to just like it rats, like experienced the delay and really learn about it, and kind of practice it. And we're, we really like to get it so that they could play it on their phone. And then we've also thought a little bit too about just having an adult, I think would be probably more likely to work. But there's another kind of training that you can do. It's called mindfulness training. And it's where you kind of really practice like paying attention to certain kinds of cues. And we're thinking that some mindfulness training for really paying attention to delays, could maybe be a nice thing. And then we could couple that with practicing, like experiencing and learning about delays. And the two together might be a really good way to go. I think.
Interesting. It's almost like self talk when you're listening to yourself.
So one of the things that are one of the models of addiction and impulsivity and things like that, that I've heard of is that you know, some of these, some of these dietary choices could be affecting the the gut microbiome, and that may be releasing neurotransmitters and things that that may be impacting how people behave. What are your thoughts on that? How much of an impact do you think that that has?
I'm certainly changing their micro. How's it going? We give them the phases that we get them. And I mean, the gut brain axis is obviously becoming very popular because this is recognition that I think was the serotonin. I can't remember what it's a high pretty high percentage of serotonin where the precursors, like rely on things in your gut. So I think without a doubt, it's a little far afield for me, but I would think the microbiome is pretty key as well.
Yeah, I think that's a fascinating aspect of it. I saw also in your in your publications list that you have looked at a little bit of the social factors that may be influencing some of this stuff, too. I'm fascinated by the rat Park stories from several decades ago. Bruce Alexander, right, we started all that. Are you doing something similar like that? And then and looking at how it impacts impulsivity. So maybe you could start from that idea, and then talk about what you're doing?
Yeah. So there's two. So this really relates to enrichment. And it's, it's pretty well established, the individuals who live in more enriched environments, you know, have a lot of, you know, better self control, better coping skills, the kind of things that we see with the kids who can, if you will pass the marshmallow test.
Enriched in what, what do you mean by enriched?
Well, in terms of people, this would be like having a lot of opportunities to like, learn and advance yourself, like after school programs, experiential, yeah, experiential kind of, you know, environments who, and then also having, you know, a warm house to go home to and healthy food to eat. In rats, they stimulate enriched environments by giving them both social enrichment. And also you can give them novelty enrichment, the novelty enrichment kind of stimulates the opportunity for experience. So you literally give them toys, and then they can interact with the toys and kind of get this novelty enrichment effect. We have done some work with both the social and novelty, we found that social enrichment, promotes self control. So even just having one other rat with them, just having a buddy was actually enough to significantly promote self control. We actually found that giving them toys partially reversed that effect. So now they were getting a new toy every day. So they were kind of like the spoiled rich kids. Maybe you're having like less frequent changes in toys, maybe it'd be better. But we were kind of like over almost overreaching now with the toys. And that actually kind of backfired a little bit, which is interesting.
So it's always try to start to scale some of these findings. Globally, right? Or at least in the United States, where we're seeing an increase in Well, some people say an increase in impulsivity within the general population, but certainly obesity issues and things like that does. How does that translate? You think that or the fact that more people are looking for meaning or maybe feeling more lonely in the social isolation and all that are having an influence on obesity in the United States? And that's, you know, sort of that's sort of part of the explanation.
I think that's certainly could be possible. I think there are probably a lot of variables driving that. And no, I, I've seen things as well about the kind of new, more like social media culture where people don't actually interact physically with each other. So you may have a lot of online friends, but if you don't actually have, like, face to face time, that actually seems to be related to a lot of problems with like anxiety and depression. It suggests that maybe we actually need physical contact with people to really like, get the effects of the social enrichment.
But somehow, we don't really know what kind of social enrichment might help with impulsivity? Is that,
Yeah, I mean, yeah, I don't think it really know a lot about that. But I think certainly like having some form of physical contact, you know, it seems to be a good thing.
So was this, what you're talking about the same sort of thing about drug addiction? I remember reading some rat studies, right about sort of the social network really reduced, right?
Yeah. And of course, impulsivity addiction are strongly interrelated. So I think they're probably affecting the same systems.
Interesting. So can I go back and ask about sugar, because we're talking about fat and it was fat that you sort of labeled as are the saturated. So also, we should distinguish are just not all fat, because you were looking particularly at these processed fats. Right, you know, but then sort of one of the things that's happened in nutrition is that people have realized, Oh, the fat was the boogeyman for a long time, right? And, Geez, it's not nearly so bad, right? And certainly not all fats, right. But sugars, perhaps much worse for like, a lot of health effects, right. So. So you're looking at both of these and you saw, particularly the process that seemed to have a longer term effect is that sort of I don't know, how does that line up with sort of this shift in understanding recently about the health effects of sugar versus fat?
Yeah, well, I would say I mean, the sugar did produce effects. It just was it, they rebounded, they kind of looked okay after they stopped eating the sugar. That suggests to me that maybe the effects of the sugar are really quite qualitatively different from the fats. And we know that sugar is addictive. And that it actually getting exposed to sugar alters your reward system in a very similar way, actually, to taking drugs. And it may be that if you just go off sugar that you're able to then like restore your normal reward system functioning again. So I think that's why we probably don't see the pervasive effects.
But if you're on sugar, if you're on sugar, it's a bad thing. When you're on sugar without a doubt. And, you know, sugar is definitely associated with a, you know, a whole host of other health problems as well. So yeah, it wasn't trying to just make fat, the bad guy. Sugar is pretty bad as well.
What does sugar do to the reward system?
Well, it seems to like dampen your dopamine response. So that you actually kind of need You need to eat more sugar, for example, to feel the same, like positive reaction hedonic reaction that you would feel when you maybe used to eat less sugar, much like you see with drug use.
So if you, you know, if you have a couple m&ms one time, the next time to get the same height as the EB three m&ms and that sort of thing.
Yeah, I mean, we're less. That's really, you know, it drives people that want to eat, eat more of it. Yeah.
And, and in fact, but we got to specify here that we're, I think we're limiting pretty much to sucrose as opposed to glucose. Yeah. So sucrose m&ms? Glucose, popcorn? Sure.
So in Okay, so So what's going on there? What's the difference in why?
Well, they're different sugars. They're different. Different structures, they're processed differently in the body of sucrose, glucose, one fructose, right? Correct. Yeah, yeah. Glucose comes in a variety of polymer sizes and complexities. And it's processed very, very differently.
So its impact on the brain and body, it could be different. It's causing that sort of thing. Oh, certainly.
Yeah.
Another thing that I saw that you were getting into is you started studying female rats for some of these studies, too, because typically, it's a male rat that's used, right? Do you see? Are you seeing differences in sex and gender, how that how that's making a difference in some of these results?
We found a little bit of an effect of gender on a result. Again, this is all the rats. But basically, two things. One, is it females, she just regardless of whether you give any kind of intervention or anything, seem to be more self control than males in their choice behavior. But in terms of looking at the efficacy of our interventions, we actually found that females were more variable in, you know, more individual differences and their reaction to our interventions. But overall, there was no sex difference in efficacy of the intervention. So that was kind of promising, because it suggests that you could still, you could deliver an intervention to females, and it would be just as effective as it was in males.
Could you say something about why it's only been male rats for so long that have been used and not so much female rats? Like this is true in general, right of the field?
Yeah, the issue really has to do with estrus cycle. So this poor girl rats, they go through estrus every three to five days. And I think it's maybe why they're very their behaviors more variable, is because their their hormonal environment is just turning over so frequently. I think the traditional way of kind of dealing with that is people either would measure their estrus and account for it, or they would ovariectomized them. So that's where you, you know, you remove the ovaries, and then that stops them from cycling. But that's not really ideal to do, because I knew now I've got a group of rats that had a surgery, and then your males didn't. And so that's not really good either. And so I think it's just mainly because people felt like they needed to control for estrus, but then it's really hard to do. Of course, we don't do that in people, right. So in that sense, like from a transactional standpoint, in our work, we just let the females be, and we're like, they're just going to do what they do. We also just recently developed a modeling technique to account for estrus in our data. We do live regression analyses, and we actually just added the sine wave component in to our regression, and we actually found we detected in estrus cycle in our choice behavior was there in the females and we also checked for males there was no estrus or in our male rats, so. So we think that maybe we can just account for it statistically moving forward, trusting.
And so that's specifically about impulsivity, the same choice function. Yeah. Yeah. Interesting.
You're really addressing a lot of different aspects of this seems to be very, very productive, very broad based. What's the next question you want to ask?
Yeah, well, I've got a few things in the works right now. One is we actually are very interested in trying to delve into the dietary research more, we want to try to get a little bit more like the brain mechanisms of particularly the high fat diets. We're also wanting to use our interventions and see if we can rescue some of the effects of the diet on choice. And then we also have some ideas about using omega threes to possibly rescue the brain effects because omega threes are really wonderfully anti inflammatory. So we might be able to kind of do some of that rescue of the effects of the diet on the brain. And then we've got some other things in the works. I'm actually working on a collaborative venture where we're wanting to do some genotype analysis of our rats to see if we can identify genes that might predict individual differences, as well. So they will probably still keep working on our interventions. We want to start delving a little bit more just all the brain mechanisms of those.
But you're looking at the same background popular, they're all what Sprog douleurs, Italy's same temporary, it,
If you start looking for doing genetic analysis to sort of start looking at different different groups of different populations are at seven different types are like and how many actually I don't know anything about this is there, there are a whole bunch of different kinds of rats you can get for these kinds of studies are worth
playing to go there, because it to do proper gene analysis, you need about 1000 animals. And it's pretty laborious to do these tests on them to figure out their impulsive choice. So we probably would only start with one this day with our Sprog dollies. But you could ultimately do that if you had the resources to do this kind of testing.
So that I know this is far afield what you do, but sort of what's the difference in all these different routes? I mean, so this is like this went back to the replication crisis is one of these kinds of things we sort of in you talked about the difference between sort of trying to get very specific in control and power, right, you know, there's this other thing that sort of control for as many variables as possible, but then that restricts your ability to then generalize, right, you know, so what are the factors that are in choosing your, your model organism when you do all these studies?
So there's the outbred versus inbred difference, which is a really big one. So outbred animals are ones where, you breed them with individuals from other lines, so that the genetic stock is always varying. And there are different strains that have different original source animals, and then they, you know, continue breeding from there. And then the inbred is where you breed within a line. And they will oftentimes do that to create animals for specific models.
homozygosity increases.
And so there's like, we have done some stuff with strains that were in bred like, that were developed for specific functions, like, turns out these, these one rats are called spontaneously hypertensive rats, they were bred specifically to be a hypertension model. But it turns out, they're really hyperactive and impulsive. It was just sort of accident. Yeah, so I think they have special animals they bred for obesity research. So and then, of course, you can also do, you know, genetic knockouts and create special models as well,
Across all of these rat models that are out there, do they what's the rate at which they transfer to human applicability, right. Like there's a big issue in pharmacology that, you know, they see effects in rat models, but then when they try to use them in human populations, they're not able to really see anything, right. How well does that transfer? Just a guess?
I think that it depends a little bit on your questions. So I think if you're certainly if you're dealing with things, where the behaviors you're looking at are likely to be very kind of high cortical type functions, you're probably not going to get as good a transfer because rats have a pretty underdeveloped cortex. But for more kind of lower level stuff, or you're dealing with, like reward system, for example, that seems a lot of that seems to transfer pretty well. We I mean, our decision making work that we do, I think we're dealing with fairly low level processes. So I think there has been good translation there. But it's always a challenge in terms of the translation issues, and I think you just have to try and see if it works or not.
Yeah, I mean, yeah, you have to do the basic research. Basic Research.
Yeah, I see you moving to a larger scale? Because you know, because this is global food systems and things like that, right? Do you have any? Do you have any ideas about like governmental policy or school lunch policy or anything like that you would like to see to help with obesity issues and children and that sort of thing? What are your thoughts on that?
Well, one of the things that I've really been thinking about quite a lot with children is it just an oftentimes don't really have choice about their diet. And so they may be getting exposed to foods that could then you know, set up a pattern where if they're really impulsive, because they ate a lot of bad foods when they were younger, that then could be set up to a lifetime of impulsivity and unhealthy eating. So I think it is really essential that in cases where, you know, we're determining the diet of the kids that we really make sure that they're eating foods that are good, not just for their bodies, but for their brains as well. So I think that's a really essential one in terms of policy.
So like making sure that the school lunches and things have the rights, the right composition, and that sort of thing right now. It's really interesting. It's something we don't often hear enough about, probably.
Yeah, I mean, you could give a healthy food. And it's something that seems like a well balanced diet, like maybe you give them some lasagna, but if you use a saturated process fat, when you eat it, there could actually be problems lurking in there that are gonna have a negative impact. So thinking about the ingredients of food as well, rather than just the end product of the food.
So gonna ask about effect size, because it's something we started with, right? So of all the other factors that sort of might affect impulsivity, right? Sort of, you know, variety things, you're talking about SES, socioeconomic status, and sort of all these other things that sort of affect us, right? So how, how big is the dietary effect compared to these others, just with respect to this impulsivity issue?
Certainly in our rats, it's quite, it's pretty big.
But you're not looking at a lot of other variables there either. That's kind of their control. That's one strain of RAD. And it's sort of like only a small certain environment, right?
Yeah, yes. I think if you put it in context, where there could be other moderators, it's going to be weaker in people than it is in the rats, where we have the full control.
So in terms of like, non dietary stuff, right, sort of the food, sort of the type of food versus like enough food calories, right, sort of to feed the brain growing and development versus sort of other kinds of factors, what's your mean, for and actually, sort of, even with food, like choice, having choice, like learning how to make your choices? That's one of the things that you talked about, sort of what other kinds of recommendations do it's hard, it's hard to translate basic research into recommendations. Right. So but what are the things are you concerned about sort of about, especially raising kids?
I think another thing that I have thought a lot about is that we are a very instant gratification society, I sort of think back to, you know, when I first like use email, and how long it took to boot up your computer, like, get your email open. And now if it took that long, I would be going crazy, like what's wrong? Like, why is it taking so long? I think there is like value in making kids wait for things, and kind of not just automatically fulfilling that instant gratification. And that can be a way that really self control can be just built into upbringing, if you don't just automatically always, you know, go for the fastest option. I think it's good to be bored a little once in a while. And this promotes creativity, right?
Yes, it does. Yeah. Do you have any you have any thoughts on the in this is sort of the kind of out of left field. But do you have any thoughts about how like things like bad food are advertised and the impacts of that might have psychologically on these sorts of things?
It's really interesting, the advertising is fascinating, because it turns out that we form associations between food labels and the foods themselves. So that McDonald's arches elicits the same response as actually a hamburger in our brains, which is really fascinating. And I think in terms of that, I mean, the labeling is actually you know, it's it's eliciting desire to want to eat the food. So I think we're being mindful about those associations, I think it is probably definitely important. Another issue, and this, again, is going pretty far afield for me, but I know that you know, in the cereal aisle, for example, they put the foods the, at the level of sugar. So and I mean, we know that with decision making, that things like that actually really do influence your decisions if the food that you first see is the one that you're most likely to pick. So maybe also trying to combat some of those factors would be a good thing.
Yeah. And this is one of these like, really basic things. It's sort of been behind a lot of what you do and you talk about but sort of it's hard for I mean, even when you know a lot about it, it's hard to Think about yourself as you know, as a, you know, your the processing the thinking we do. So much of its automatic, so much is controlled by other things, right? And we like to think we're in control of things, but you know, you just Alright, so if you feed me different food, apparently I'm behaving differently, right? So so how should we be thinking about our own selves psychologically, in general, like those are their major shifts in terms of how to think about yourself, self that you would recommend to people that's really interest me.
I think sometimes we give ourselves too much credit for being like this really advanced species, like what we do is still very much driven by maybe our animal past, if you will, I think being very aware of the importance of habits is a really important one. And that establishing habits can actually go a long way towards you being able to change your behavior, that's much more effective to establish a habit than to try to like just consciously to decide at the moment to decide to do keep with it, but it actually takes about two weeks of just daily practice of a habit before it becomes pretty automatic. So if people can just like use their system twos for long enough to get the habit established, then that habit will just kind of take over.
Two part question, when you test the rats, do you test individuals? Is it like one rat in the box being tested? Yes. Would you predict or hypothesize that that might change if there were multiple rats? And what I'm getting to is the idea of people eating by themselves versus having a meal with others? Whether that would change the that's really interesting.
Yeah, I mean, I'm, I'm sure that there's social effects, we know that. Actually, much like in people, the rats actually engaged in social learning about what to eat. So they actually will smell each other's breath. And if they smell a certain food type on a rat that's looking really healthy, they're actually much more likely to eat that food themselves. So I think certainly food choice would be influenced by other individuals.
That's fascinating, interesting. Well, we want to be respectful of your time. We really appreciate you taking the time to talk to us got John, do you have any further questions? How's it been great. Is there anything else? We haven't covered that you would like to say?
We covered a lot? Yeah, yeah.
Fascinating stuff.
Yeah. Thank you so much.
I hope everybody enjoyed. Thanks so much, Dr. Kim Kirkpatrick.
If you have any questions or comments you would like to share check out our website at https://www.k-state.edu/research/global-food/ and drop us an email.
Our music was adapted from Dr. Wayne Goins’s album Chronicles of Carmela. Special thanks to him for providing that to us. Something to Chew On is produced by the Office of Research Development at Kansas State University.