Social and psychiatric epidemiologist Dr. Erin Dunn explains how stressful events leave a permanent record on our teeth and how we can potentially use our molars and canines to predict future mental health.

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ERIN: Kids start losing their teeth when they're in kindergarten. That means you've got years of opportunity to be able to intervene, to do something, and really change life trajectories.

JONATHAN: Tracking mental health vulnerabilities in a population, or in an individual, remains difficult. And clinicians still do not have great tools for recognizing strong signals of potential issues.

Today on Pulsar, a talk with Dr. Erin Dunn, who in collaboration with Dr. Felicitas Bidlack, a researcher at the Forsyth Institute in Cambridge, are working to find just such a signal. And they have a pretty unusual candidate, our teeth.

Thanks to Facebook Boston for supporting this episode of Pulsar.

I'm your host Jonathan Fanning, an educator at the Museum of Science. And Erin, welcome.

ERIN: Hey, how are you?

JONATHAN: And to get started, often we ask around for questions for an upcoming scientist. And I think the question I got first from everyone I mentioned we're going to be talking about teeth and mental health is, wait, you can tell mental health from teeth?

So I want to begin with a two part question. What first led you to consider teeth as a possible indicator of mental health? And could you cover a little bit about tooth biology and how that makes them a candidate to capture our mental health?

ERIN: Yeah, those are great questions.

I have to say it's often so fun to just talk about teeth and their relationship with mental health, because you get people to turn their heads and they're like what? What? Teeth and mental health? So I'm not a dentist. I had no plan to ever study teeth, to be honest.

I have spent my entire research career trying to understand how to prevent mental health problems like depression. And to figure out how we could do that as early on in the lifespan as possible, because I lived firsthand growing up with a mom who had depression. And just seeing the prevalence of mental health related problems in the schools I worked in and other settings.

That just really ingrained in me this passion to try to figure out opportunities for prevention. But the thing that I kept coming back to is that we have such terrible measures in our field to be able to record people's early life experiences. And I ended up having a really amazing conversation with a colleague.

I was sharing with her my frustration and she just very casually said, have you ever thought about teeth? And I was like teeth, what are you talking about? Did I hear you right? Is there something in my teeth? Because we were at lunch at the time. And she said, you should think about this.

And that's where I started to discover, wow. There is a whole wealth of possibilities here and kind of connections here that people aren't really thinking about, and connections that they're not putting together.

JONATHAN: So what have we been missing? What about teeth makes them ideal to potentially draw those connections?

ERIN: So as our teeth are forming, they form in a very incremental process, and you can think about it as being really similar to the way that trees develop. So every year, with each passing birthday that a tree has, it forms a ring. So our teeth are really similar, in that our teeth also record these incremental growth marks.

And they do it at two different timescales, which is really remarkable. So there are one set of growth lines that correspond to essentially our daily development or our about daily development. And then there's another set of lines that correspond to weekly development. So imagine if we had this tool, which we do in teeth, that has these incremental growth lines that can record the process of development that's happening at that level of timescale.

And the other thing that's also incredibly cool is all of this is permanently recorded. So there's no turnover of the cells that are forming teeth, so all of this record gets permanently recorded. The other thing that also happens is that when there's some type of stressor.

And this is where there's a lot of uncertainty and where we're trying to really unpack this. Sometimes these growth rings can be disrupted, they can be wider, they can look different than the other incremental growth marks. And traditionally, anthropologists and archaeologists have referred to those kinds of lines as stress lines.

And what we've been doing is trying to understand, can we link various kinds of stressors in people's life to the presence of these incremental growth marks? And specifically, to the occurrence of these stress lines, to see if we can actually see evidence of our stressful life experiences showing up in our teeth.

JONATHAN: Yeah. And just quickly I'm thinking about drilling down into a tooth.

ERIN: Which, by the way, I'm realizing is the worst use of language when we're talking about teeth.


ERIN: I apologize, we're talking about drilling down. It's like, yeah.

JONATHAN: That's my question is: under what circumstances are you looking at these teeth and for whoever is donating their tooth - are they comfortable at the time?

ERIN: Yeah, exactly how much drilling down are we really doing here? Yeah. So, the good news is that what we're doing now is pretty non-invasive, because we're studying children shed teeth. So the teeth are naturally fall out for young kids. And then the big question that we're also trying to understand is where do we start to see signal in ways that's helpful to us?

Are there clues that we can get just by looking at teeth? Or do we really need to get into the more granular, sort of, tissues and to look at these different structures? Because then that's where we have to use more expensive technologies to be able to do that.

JONATHAN: So as we get down to this granular level, I wonder how other day activities might affect your results? I think you can talk to any dentist and they'll tell you proper dental hygiene is something a lot of us struggle with. So how are you separating out the signal from the noise?

These major stressful events from everyday wear and tear or lack of dental health or a sugary diet, things of that nature.

ERIN: Yeah, that is such a good question. And we spend so much time in our research meetings talking about that, because exactly as you said, how do you derive the signal?

And how do you piece the signal from the noise? Especially, when you're studying children who might be experiencing a range of stressors that are more chronic. And where they might be more likely to be drinking sugar sweetened beverages, which then certainly leave behind bad things in teeth. I think this is where we've been trying to think about how can we address some things that are kind of part of typical development versus a typical development.

And what are the kind of creative workarounds that we can think through to be able to interrogate those? So, one thing that we have done is try to create new standards to be able to understand and model meaningful differences even when you see grinding. So most children grind their teeth.

So that means that you're limited in some ways with what you can see from the enamel. But you can start drilling down into other tooth tissues, like the dentine, which underlies the enamel, to be able to think about and measure some of the characteristics there. So that's kind of one thing.

The other thing too is what we've also been trying to study, children who have a range of different kinds of early life experiences and early life adversities. And that's where we've been differentiating those who might have more acute and kind of one time stressors from those who have more chronic and prolonged stressors.

So, for example, one of the things that we're doing now is recruiting research participants for a study, where we're trying to understand the effects of the Boston Marathon bombing. So this was a one time stressor. It was a massive stressor. It significantly impacted our Boston and Cambridge and really, Massachusetts community.

So we're in the process now of trying to recruit moms who were pregnant when the bombing happened to see whether we see evidence in their children's teeth of that mom's exposure to the bombing. Because those children would have been starting to form those teeth while they were in utero.

But we don't have all the answers. And this is something where we're actively trying to understand and be creative and thoughtful about how we problem solve around this so that we can get meaningful effects and really disentangle the signal from the noise

JONATHAN: And where do you see this research going? I hear you talking about, sort of, in utero exposure to stressful events.

So are you hoping that this sort of test might allow you to just observe the impact of major events like that? Or do you think this could be used as a predictive tool at some stage?

ERIN: In terms of being able to predict mental health related stuff, I think that is a whole other possibility. So, the idea is if we know that childhood adversity is a major stressor and a major predictor of future mental health problems. That means that you want to be able to measure people who've been exposed to early life adversity, because it provides a window into people's future risk.

But it doesn't tell you about whether people are going to go on to develop a mental health problem. It doesn't tell you anything about their mental health. So I think of it as a potential tool that you can use alongside other measures. So, for example, being able to interview a mom or another caregiver about other kinds of early life experiences.

So I think one of the things that we've really learned as a scientific community is that there's not one answer. So there's no silver bullet that's gonna be able to help us figure out how to prevent mental health problems. It's gonna take a number of different tools, and we have to use them in parallel.

And we have to use them in ways that are complimentary so that we can really ultimately achieve this goal. What I, sort of, always come back to is these things naturally fall out of our mouths. And how many teeth are sitting in landfills that could have actually been used in a way that could have done something that's just really meaningful?

So to me that's the kind of ultimate motivation for this work is, how can we think about teeth being used alongside other kinds of tools and other kinds of data so that we can make better predictions.

JONATHAN: Yeah. And just to sort of wrap up, you have mentioned the Boston Marathon bombing.

Are you focusing on any other major potentially traumatic events in your lab right now to see if you can identify these very clear signals?

ERIN: We're also using data that exists from other projects to try to look at other kinds of stressors. It's some of the work that we are exploring.

Really goes from, kind of, a micro to macro perspective. So everything from mom's experiences of mental health, all the way up to neighborhood level characteristics. So we're trying to not leave any stone unturned, in terms of being able to identify potential stressors that could show up in teeth.

Anyone who's interested in learning more can visit our website, which is teethforscience.com.

JONATHAN: Awesome. Well, thank you so much for stopping by and chatting with us about it a little.

ERIN: Thank you.

JONATHAN: And thank you to our listeners. If you have a question you'd like to ask a guest scientist, you can send them to sciencequestions@mos.org.

That's it for this episode of Pulsar. Until next time, keep asking questions.