Tina Duhaime, MD: How Is Climate Change Related to the Human Brain?

Q: In May, 2019, a report issued by the United Nations stated definitively that human activity is changing the planet at a rate unprecedented in human history. However, from any of us, the massive scale of this problem makes finding solutions feel daunting, if not impossible.
But for Dr. Ann-Christine Duhaime, it’s not hard to explain our struggle with climate when you consider how the human brain works.

Tina, a pediatric neurosurgeon by training, has devoted much of her research to understanding how the brain’s reward system might be related to our drive toward increasing consumption, which has increasingly and dire effects on the planet. She hopes that by better understanding these issues, we can better—we can design strategies to successfully engage everyone in combating climate change, especially in the healthcare space. So welcome, Tina.

A: Thank you.

Q: All right. So I know sustainability is a topic that has become a big part of your life. Can you start by talking a little bit about what sustainability means to you?

A: It’s a tough word, and it’s a word that people have had various opinions about, because it means so many different things to different people. And people in the field of climate change, environmental decline, have actually gotten a little bit away from that word sustainability, because it has become a little bit hackneyed.

But as a starting point for a conversation, it’s not a bad word, because most people have some sense of what people are talking about when they mean it. And when I have used it in talking to other people, what we’re talking about is anything that will get us closer to solving the environmental problems that we have.

Those are huge problems with multiple facets. And one can tackle them from many directions. And that’s why the word “sustainability” isn't a bad umbrella term that people understand what you are talking about.

Q: When you think about that umbrella, what fits underneath of it?

A: Climate change is the sort of most pressing one. And the way that people have become increasingly concerned about the rapid change in temperature. And that’s the one that probably there's been the most attention to. But other things are related. For example, land use, waste, the whole plastic problem. I mean there are many, many elements to this. But you can put them all under the umbrella of, largely, human-changed world.

Q: And I think some people listening might be surprised that we have you, a neurosurgeon, here talking about sustainability. So can you talk a little bit about why it matters to you, and how you got involved in this work in the first place?

A: I started out my career with two goals when I was choosing what field to go into. And the first factor was, what problems need the most attention? And then the second criteria for me at that time was, which ones are most interesting?

And unfortunately they didn’t line up. So when I was in school trying to choose what to do, it seemed, at that time, that the biggest problem facing the world was human population growth. And it seemed to me that population expansion of humans was at the root of many other problems, including resource utilization, and you know, war, and peace, and starvation, and poverty, and environmental decline, even back then. And when I say back then, I'm talking about in the ‘70s.

But the things it would take to do that were not very well aligned with my interests. And my interests, at that time, had to do with the brain and behavior. And those interests really were what fueled my educational endeavors, and ultimately what fueled my career.

And so the two things took separate paths for many years. But I never lost sight of the issue of population, which then kind of merged into environmental decline.

So I went into medical school and neurosurgery, because there is nothing that is a more direct one-on-one, up close and personal view of how the brain works than neurosurgery. It’s an extraordinary privilege to be able to interfere and intervene and assist, hopefully, someone’s brain malfunction, and watch how it works, and watch how it recovers.

And pediatric neurosurgery also adds in the element of development and plasticity, and how children grow, and what they're exposed to, and how you can help them recover. So these two themes were separated for a long time, except I never lost my concern and worry about the big problem that I had left behind in my career choice. And, for that reason, I felt a disconnect that was bothersome, frankly. Part of the problem was resource utilization.

I've always been privileged to be in the high echelons of academic medicine. But what places like that require is putting enormous human and financial resources into solving problems that oftentimes help one patient at a time in small ways.

It occurred to me along the path that not everybody in my field shared that discomfort. And that distinction was problematic for me.

When you're in neuroscience, everything has to do with neural networks and how the brain works. And so, as it became clear that climate change and behavior were intimately linked, the way I saw an opportunity to bring these things back together is that one of the big parts of the problem is human behavior. And it seemed to me that this makes perfect sense if you look at it from the point of view of how the brain works.

But I think, when it comes to the issue I am interested in, which is our planetary future, I think it is part of our potential jobs in healthcare to think about that, because that is a health issue.

There isn't any doubt that climate change is a real thing. I understand there are people who don’t accept that. But I think the science is overwhelming that this is a real thing, and that this is human caused, in large part. And there isn't any doubt that the changes that will continue to be caused by this will affect human health.

And it isn't just the health of people in places that will become barren deserts, there are effects that are health effects right here in our own neighborhoods, having to do with simple things that we’re all becoming aware of--changes in insect and bird populations, changes in the distribution of certain diseases, changes in pollution and the effects on asthma, changes in seasons, changes in agriculture.

In the more global picture, this is going to affect the health, out of proportion, in places that are not as well resourced, getting back to that resource word, places that are as wealthy, frankly, as the developed countries of the world. So this is going to hit poor people harder, both locally but globally. And it’s projected to cause food shortages, water shortages, migration, war, all of these have major effects on health.

Q: I imagine, as someone who has this deep understanding of the brain, you bring a different perspective to this than a lot of other people. Can you talk about how that impacts your understanding of these issues?

A: If you understand the brain, I think it helps you be less judgmental. The reason people have the opinions they do are good reasons. And it’s not deterministic, in the sense that, if you only understood everything about the brain, you would understand someone’s point of view. But the brain is designed to help you survive.

And it has amazing systems in place to help you survive by reinforcing behaviors that helped you survive at the time the brain evolved, in the prehistory of humanity. When you look at how the brain is designed, and you apply it to modern life, many of those features are no longer adaptive to the way we live in the modern world.

And the simplest analogy is eating. In early humans, if you didn’t eat, you died. And so your brain evolved extraordinary, powerful mechanisms to help you want to eat things that gave you calories, for example, or kept your physiology in balance.

So think of what those things are: sugar, fat, salt. We love sugar, fat, and salt. You love them, not because you're a weak human being, you love them because those are wired in to the way your brain works, through exquisitely engineered feedback loops and reward biology. And those genes were selected.

If you look at all of human behavior through that lens, you can understand why consumption is such a problem for us.

One of the questions that I had to answer in this exploration is, “How much of the carbon generation has to do with our individual behavior, compared to sort of things we can't control? And how much of this problem has to do with other countries?” for example.

And it turns out that the high income countries have contributed more to this problem than anyone else. Currently, China is producing more carbon than the United States is per year. But our per capita consumption, and production of carbon, has been way at the top of the list for the longest time. So if you look at the global burden, it’s us, it’s our problem.

And the environmental writer, Bill McKibbon, in 1998 he wrote this article in The Atlantic that was three parts. And he described this, I think, very effectively, as, if you imagine carbon, and you imagine a balloon that someone carries around, if you look at people in the developing world, they're like the little balloon at the side of the parade on a string. That’s their carbon output per year.

We here in Boston, most of us, we are carrying around Macy’s Thanksgiving Day Parade balloons over our head, of what we consume, and therefore produce. So it is us.

And then, when you ask about how much of that can you change? When I went down this path and tried to understand that, not by original research, but by reading many other people who have written about this, who know a lot more than I do, you can estimate that about half of it is under your individual control. And about half of it you can't control.

If you think of amounts, the International Panel on Climate Change came down with an idea that currently, around the world, our average per capita carbon consumption is about five tons per year. In the United States, in the affluent portions of the United States, we’re at about 20.

We need to get down to less than two.

Q: So 90% decrease.

A: Yeah. And so one of the questions is, what is it about our brains? Is there anything about looking at our behavior through the lens of how our brains work, that make this a particularly difficult challenge for us?

The answer is, everything is about the brain. Every decision you make is—is made by your brain.

And it’s not like it’s made by your brain in isolation, like it’s a little control box up here. Your brain is designed to intersect with the world you live in, minute to minute, second to second. You absorb things. You change behavior. You change what's rewarding and what’s not rewarding.

So we’ll give you an example from neuroscience, which is the dopamine story.

So Parkinson’s disease is a disease where particular parts of your brain have a problem with the cells that create dopamine, in a very specific place. And it mostly affects your movements. But that network is so interconnected, that it also affects other aspects of your behavior.

And it became clear, over decades and decades of work, that you could actually replace dopamine and treat patients with Parkinson’s disease. You can do it by two ways. One is medication. But you can also do it by putting a deep electrode into the part of the brain and stimulating it and changing the dopamine that way.

And what was found, both with medications and with the deep brain stimulation is, if you give too much of them, those patients who never had this problem in the past could change their behavior in weird ways. And the weird ways would be about consumption and dopamine. So they would become compulsive gamblers, sometimes compulsive shoppers, compulsive internet users. And the reason seems to be, that when you give back dopamine, it goes to the place that there isn't enough. But it also goes to the place that’s still working. And now you have too much.

So this was a fascinating link between certain kinds of behaviors, including consumption behaviors, like shopping, and this whole dopamine story.

When you look at things from that point of view, and you think, when we were cave people, you never had enough. You were always cold. You were pretty much always hungry. You evolved this mechanism that said, “Get more. Eat more. Get more stuff.”

Those things are still working.

And so, when you have a choice of having three pairs of shoes in your closet or 20 pairs of shoes in your closet, you can say, “I need them for work. I go hiking. I need those.” And it’s partly that maybe you do, the way we live our lives. But it’s also partly that getting that new pair of shoes, you are wired to get a reward for that.

There are other things, though, besides consumption, that also work the same way. 

And humans were designed to have a wide variety of traits within any given population. And this is why it’s not surprising, no two people are alike.

But looking at behavior that may be relevant to why we’re in this environmental problem, what is it about the brain that makes this hard for us to not behave in certain ways? And can we tap into what we know about the brain, to make it easier, rather than just saying, “Don’t do that. Don’t eat that much. Don’t have that piece of cake,” that doesn’t work.

But there are things that do work. And, if you really want to solve this complicated problem, you’d better know about what actually works, because we need to change our behavior.

Q: It leaves me wondering, is there hope for our brains? You know, are we stuck? It’s been a long time since we were the cavemen. And our brain’s still evolving. So is there hope? Or are we kind of stuck in this space of caveman brain, so to speak?

A: To try to answer that question, what I did in my journey through this topic, was to look at what behaviors are hard and easy for us to change, apart from the environmental world? So what I read about was addiction, overeating.

But I also wanted to look at other things that are more culturally-based. So one of the things that I read a lot about was the Ebola crisis in West Africa. That was a great example of how do you change people’s behavior? And what about certain behaviors is culturally influenced and culturally-based?

So we’ve talked about biologic urges, like eating. But there are many behaviors that are designed to be influenced by the input from the external world. And the concept here, that I found really valuable, is this concept of, in the neurologic sense, the word “gullibility.” And this isn't gullibility like you believe something that’s crazy. Gullibility is the sense that children, and adults too, are designed to believe what they are told by authority figures, particularly their family.

And that makes sense, because if you were about to run over a cliff, or fall into a pit, or drown, or you name it, touch a wasp nest, and you didn’t stop when your grandfather said, “Stop!” you’d be in trouble. So that tendency to listen to and believe and respond to an authority figure telling you something is part of, I think, our evolutionary inheritance.

But it plays over into all aspects of life. So we see this in my own field of surgery. If you were taught something in residency, residency is a little like the Marine Corps. If your mentor said, “You put the stitches in this way,” or, “You never give that drug,” or, “You always do this or that,” and particularly if you're yelled at if you did it wrong, you see people, 40 years later, that will still do it the same way. And I'm guilty of that. Because what your mentor tells you has an enormous impact, okay.

That’s how your brain is designed to work. And so, when we think about human behavior and changing behavior, people have strong opinions about things for all these reasons.

Fat, sugar, and salt, okay. It’s hard to overcome that. But you can overcome fat, sugar, and salt if an authority figure tells you, “You know what? For you, this is going to kill you. Like you need to change.”

Like maybe that’ll be enough to get a change. But we also know that the way the brain is wired to change, is also through substituting other rewards.

So the reward of a chocolate bar might be overcome if you're in a social group, where everyone talks about how great you look, and that you lost a pound.

Other rewards. Okay, you can't have a chocolate bar. But guess what. You can have this whatever, substitution.

So through what we know about addiction, through what we know about other kinds of problem behaviors, behavior can change.

And in the Ebola crisis, what was substituted was, the authority figures in the community were enjoined by the public health people to address the concerns of the people, which were, “If I don’t follow these funeral practices, bad things are going to happen to me and my family.” And it didn’t help to have authority figures that were not their authority figures, like people that came from outside and said, “You must do this.”

What worked was getting people who were their authority figures, to address their concerns in ways that the fears they had were addressed, and the things that were rewarding to them were substituted by other things that were equally rewarding. That’s how change occurs. That’s because that’s how your brain works.

Those same principles have been, and can continue to be applied to this grand challenge problem of climate change and environmental decline, because people can change their behavior.

Q: Are there other solutions that you think about, in an ideal world? Those substitutions we could make are habit changes that we could—habit changes we could encourage?

A: You’ve hit on a really important concept, which is the term “habit.” Habit is a great term in neurobiology, because habits are designed by your brain to be hard to break. And this is why, when you’ve given up smoking, you can still get cravings long after the nicotine has been out of your system, because your brain is designed to associate the context of a reward with the reward itself.

And that’s why habits are designed to be hard to break, because usually, not an addiction, but in regular behavior, they take a long time of consistent reward to form.

But let me give you some examples in the climate change world. Many people have created lists of things that people could do if they want to have the biggest impact. And a lot of times, people want to have an impact, want to do the right thing, they just don’t know what those things are.

So one list that one group came up with were these things that actually, for most people in the developed world, make the biggest difference. Number one is transportation.

So I’ll give you an example in personal transportation that is in my world. When I was a junior faculty member, I had young children. And I had to be on call. And it was rewarding to me to get to work, no matter what.

Plus, I had young children, and safety was important to me.

So as soon as I had gotten out of student debt, and I had enough money, I was going to get a new car. I was going to get rid of my old VW Rabbit that had like the head liner falling down, hitting my head.

And so I bought monster SUV that had steel cage sides. And that my kids would be protected. And it would go through anything. And if it got 12 miles to the gallon, I was lucky. But at that time, I just—it seemed all the rewards of having that particular car, you know, those were important to me. As time went on, and I was like, “Oh my God, this car gets 12 miles to the gallon,” that wasn’t rewarding to me anymore. And now I have a very energy-efficient hybrid.

And it turns out that carpooling, keeping air in your tires, none of those have as big an impact as getting a higher mileage car. So I now have like a 60 miles per gallon car. It doesn’t make me feel as, you know, cool as that other one did. It’s not my first choice, in terms of style, or anything else.

But my substitute reward is, it gets really good gas mileage. I only have to fill up my car every three weeks. But the point is, that was a substitution. And my rewards are different, because my own gullibility is, this problem is increasingly important. And this now has risen on my priority list.

The other things on that list include, if you can make your house more energy efficient, that’s a high one. Plant-based diet. Air flights.

But if you are supposed to be at, you know, on average in the world, five tons of carbon a year, we need to get down to two. Most of us are somewhere around 20. One transatlantic or transcontinental air flight, round trip, is two tons. So what people who make these lists say is, “You don’t have to give up all air travel. But if you can cut out one trip a year, that’s got a big chunk of impact to it.”

Q: I want to go back to the question of the solutions and the rewards. And it sounds like, to some extent, these rewards are individual. So what feels rewarding to me might not feel as rewarding to you. Which strikes me as a big challenge, if we’re thinking about how do we scale these solutions.

A: I think that’s absolutely right. And there are different people for whom different things will resonate. And we have to understand that. There's a wide variety. This is not a one-size-fits-all problem. So I’ll give you some examples.

For some people, exposure to nature is intensely rewarding. For most of us, exposure to nature is a reward, but it’s not the same, to use a simplistic verbiage, the same dopamine rush as eating an ice cream sundae.

Why would that be? Because when our brains were being evolved, we didn’t need to have nature. It was everywhere. In fact, nature was probably dangerous and the enemy most of the time. So we didn’t evolve a thing that said, “Get nature right now, or you're going to die!” you know. We just don’t have that. However, there's a huge amount of evidence that suggests that exposure to nature is beneficial for most people, most of the time.

And most people, when given a choice between photographs of a natural versus a human-built environment, will choose the natural environment. So for some people, the reward of nature helps make them more environmentally conscious. And that’s the gateway to pro-environmental behavior. That’s particularly true for children.

And exposure to nature is an important motivator for pro-environmental action.

So for some people, preservation of nature and exposure to nature is the carrot and the reward that resonates most with them.

For other people, as we mentioned, things like social justice is the motivator, both locally and globally. For some people, health is the motivator. So for some people, it’s like, “I want to be healthy. I want my children to be healthy.” So those people will align with efforts to improve health and health and environment align.

For some people, it’s a matter of science and problem-solving and agency. This is a real problem. I want to solve it. These are the scientists, the policymakers, those kinds of people.

For most of us in our daily lives for whom this is not the focus of our life, we want to be good people. We want to do the right thing. And most of us just don’t know what to do.

For those of us who are in the healthcare field, our job is to get the word out for you, as to what can make a difference.

Social rewards are enormous. So many different pathways of social reward have been found to be effective for pro-environmental behavior. In Europe, there, for many years, has been a series of programs where whole communities can come together, and they set their own environmental goals. They have competitions. They have parties. They have rewards.

And it’s about how much solid waste did you cut out of your daily and weekly production? How much did you buy stuff that was not in plastic throwaways? And then you're socially rewarded.

So there are many, many ways that these rewards can be thought about, from a brain perspective, and a behavior perspective, that will appeal differently to different people and different segments of society.

Q: Something that I've been thinking about, and I'm curious what you think, is there are these systems that have been set up. For example, I've read a lot about the clothing industry. And, you know, we have all this fast fashion. And you can just buy, buy, buy. And then, when you're done with it, send it off to Goodwill, and don’t think of it ever again. And for many years, the clothing from Goodwill, or the secondhand stores, was sent to China or to Africa. And now, globalization is changing the global economy and the fashion industry, and the way people think about these things. And they don’t want that clothing anymore.

So this system that was allowing us to behave in a certain way is starting to break down. And it’s going to force a change. Do you see that happening across sectors?

A: You bring out a really good point, that I haven't addressed. And it’s the elephant in the room, which is economics. So so much of what is resisted, in terms of change, has to do with the fact that, if you're the head of a company, your reward doesn’t come from being an environmentalist, in most instances. Your reward comes from your profit margin and your shareholders. 

A former professor of mine who’s written a lot about this, named Peter Sterling, who’s a neuroscientist, his belief is that part of the problem is that, in modern life, the way our reward system evolved to be maximized, which is small, intermittent, unexpected, variable rewards, is not what happens in modern life. In modern life, you get a paycheck on a schedule. You might get a bonus if you did something good, but it’s not immediate.

And so his belief is that this consumption idea is because we actually are not rewarded enough in the way our biology is designed to be rewarded. So instead, you might buy another piece of clothing. And it makes you feel good for about two days. But then, you see another piece of clothing in the window, and you want that one, because that makes you feel good for another two days.

So, as more people become aware of this environmental problem, just like my attitude towards my car changed, people’s attitudes towards consumption is not immutable. It can be changed, by social rewards, information, and so forth.

And it’s, again, a matter of substituting rewards, and recognizing that, to say, “Just don’t buy anymore clothes,” that’s not going to work. You’ve got to do things differently and substitute reward for how your brain is designed to function.

Q: You talked previously about children and nature. And I know you’ve done some work thinking about what a green hospital might look like, particularly a children’s hospital. So can you talk a little bit about what that is, and why it might be impactful and important?

A: It’s been my opinion since coming Mass General, about 10 years ago, that having a coalescent physical space for our pediatric hospital would be a benefit on many levels. And I thought about, how can I have an impact personally? And I started to try to think creatively.

And I thought, how could we solve two problems at once? How could we do something that would be good for the future of the children we treat, that would, frankly, mitigate some of my own conflicts about these issues, that could be a prototype and an academic endeavor, an academic mission?

To do something that would create a unique environment for kids, that would pull together many of these rewards, and serve as a prototype, that we could use to study the best practices, to constantly study them as a living laboratory, to refine them, and to export what we learn.

So the idea of the green children’s hospital was, could we have a facility that brings together some of the incredible resources we have.

Can we partner with all these people to create a facility that will be, quote/unquote, “green” in multiple ways?

One is, minimal effect on carbon footprint within a healthcare environment. That’s a big challenge, because we produce enormous amounts of output. Can we minimize our waste? Can we minimize toxicity, make things as clean and healthy, like our indoor air quality and so forth? Can we do it in a way that appeals to the brain’s need for nature?

And that concept is what we call “biophilia.” Can we make a facility that feels relaxing and green and natural? And, can we do it in a way that makes us feel great, because we pulled together incredible creative resources of how to do this? Can we do something that makes us feel so good about our mission? We already feel good about our health mission. But can we do health-plus? Can we do this health mission, plus this planetary mission, plus the future of our children mission, all together?

Q: And how would that change patient care?

A: I think it would change patient care in a number of ways. Number one, everybody that walked through our doors would be exposed to the fact that this mission about the world, the planet, the climate, you don’t want to hit them over the head with it, because we recognize there are people who don’t buy this. But I don’t think there are many people who don’t believe, when they're in the healthcare world, that exposure to the natural world for children is probably a good thing.

Most people that come to healthcare want health, above and beyond everything else. So if you can say, “Our indoor air quality is the cleanest. Our toxicity is the lowest. Our infections are low because we use these surfaces that don’t require such toxic chemicals that are engineered to not have bacteria stick to them.” That’s technology development.

We don’t want your child to be tethered to a wall, so we’re going to have monitors that the child can walk through the greenhouse in the middle of the hospital and throw pennies in the fountain, and see the ants in the little ant tunnels in the Plexiglas. And we know that this calms kids. Kids with learning disabilities, kids with certain kinds of behavioral issues, kids with hyperactivity.

So besides the message and the mission that this is going to be a healthcare facility that changes health, both in the short-term and the long-term, we also hope that it will change the delivery to make the environment more calming, more appealing, less stressful, for the children, for their families, and for the staff.

Q: It sounds like a really exciting future that you're headed towards.

A: I hope so. I hope so. I think the tide is turning. I think the tide is turning in the general public, with the recent climate marches and climate strikes by children. The kids that we take care of now, in 2019, at the Massachusetts General Hospital, they're going to be alive in 2100.

We don’t have much time to change this trajectory. I feel it’s part of our duty in healthcare. It’s part of our duty as educated people who have been privileged to have extraordinary resources, both financial but also knowledge resources. This is something we can do. This is something we can do uniquely. It’s not separate from healthcare, it’s part of healthcare. It’s part of what we ought to be doing.

It’s been extraordinary the unanimity of positive response among our staff. And I think this is something that just makes everyone feel good. And I would say, from a brain point of view, what that means is, it’s rewarding.

Q: This has been so wonderful, Tina, talking to you, learning a little bit more about your work. Before I let you go, I have my final five questions.

If you weren't a doctor, what would you be?

A: A writer. Probably nonfiction.

I am writing a book, so—and I've written many, many, many technical things. This is my first non-medical book. It has been so much work. [laughter] But it’s really been fun. I believe in words.

 

Q: What advice would you give your younger self?

A: Neurosurgery is an extraordinarily energy-sapping profession. And if you want to do something in addition to neurosurgery, you're going to have to work really hard to carve that out.

Q: Is there a time that you made a big mistake that you learned from?

A: One of my most embarrassing mistakes was, I was in college. I was planning to be a psychologist. And I was young and foolish and insensitive. And I had the opportunity to talk to someone who worked in a psychiatric hospital, who was a psychologist. And since I was really interested in brain and behavior and mental illness, and how it all worked, the fact this psychologist worked in a psychiatric hospital was a big thing to me, because it meant that, as a psychologist, I could deal with these kinds of really fascinating people, and brain disorders, and so forth.

And I was working in a city planning office. And I went and told everybody, “I talked to this psychologist, and he works in a nut hospital.” And a little while later, one of the older gentlemen gave me a little slip of paper. And it said, “I was a patient there.” That taught me a lot.

Q: Yeah.

A: So I kind of toned it down after that. And I've been toning it down ever since.

Q: Do you have any guilty pleasures?

A: Long walks in nature, that’s my main. Guilty ones? Droste chocolate and almond milk pretty much every night.

 

Q: What do you consider your super power to be?

A: I would say I have two. One is a love of words and precision and language, which helps me communicate with patients, and write, and all those things. So I'm lucky to have that. And the other I think is perception of others, being able to put myself in other people’s place, and be sensitive to other people.

Q: Thank you so much, Tina. It’s been an absolute pleasure talking with you today.

A: Thank you, Amy. This was really fun conversation.