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E46. Interoception and Emotional Regulation (Interview with Dr. Carissa Cascio)

Donae 0:00

Welcome to ADHD Crash Course! Today we have Dr. Carissa Cascio who is an associate professor in the Psychiatry and Behavioral Sciences Department at Vanderbilt University. Her research focuses on the brain basis of sensory differences in neurodevelopment. She is here to talk to us about interoception. Welcome Carissa.

Carissa 0:23

Thank you, it's so nice to be here.

Donae 0:27

Dr. Cascio is actually my sister, so I am not going to be able to keep calling her Dr. Cascio. I'll be calling her Carissa, so welcome Dr. Carissa.

Carissa 0:38

Thank you so much. It's wonderful to be here.

Donae 0:40

I'm so glad you're here. Thank you for coming to talk to us about interoception. This is a big topic for ADHD.

Carissa 0:48

It is.

Donae 0:49

Yeah. Tell me a little bit about your background, why this is something that you have studied, and how it's a part of your professional life. We'll go from there.

Carissa 1:00

Okay. Yeah. I run a research lab that is looking at sensory processing, more broadly, in neuro development, and particularly in autism. We had some ideas about what this sense of interoception might look like in autism. I guess probably, it'd be good to start by just saying what interoception is, for any listeners who aren't familiar with it. Interoception is what we sometimes think of as an additional sense.

You've learned about having the five senses, but you actually have more than five. You have some senses that are coming from the inside of your body that we don't always think about when we think about, "what is sensory?"

Interoception is one of those, it is the sensory signaling that arises from the physiological processes that are happening in your body. Digestion, breathing, heart beating, all those kinds of things that are happening inside your body are activating neurons that send sensory signals to your brain. Interoception is just your brain's receipt and interpretation of those signals.

Donae 2:09

Okay, so it's considered its own sense, or is it a part of the other senses?

Carissa 2:15

It's considered its own sense by a lot of people. What gets tricky in how we define it, is where it stops. Some people would consider pain to be part of interoception, especially if it's internal pain, like a stomachache, or a headache.

Then some people think about pain more in terms of our tactile system, especially if it's pain that's on the surface of the skin. You can see how the lines get a little bit blurry about where exactly interoception ends and other sensory systems pick up.

Donae 2:47

Okay, that makes sense. Heart rate, hunger, thirst... if you have ADHD this is probably familiar, right? A lot of us miss these signals, or aren't always tuned in to pain, possibly.

Also, I know, there's been discussion about emotion, and how that's an internal experience. Is that interoception as well? How does that relate?

Carissa 3:13

Yeah, so this is a really interesting question to me. This was something that made us think about why interoception might be important in something like autism, and a lot of neurodivergent groups, because it does have a really strong role in emotion and our perception of emotion. Psychologists who have studied emotion for a very long time have recognized this link.

They have recognized these physiological sensory changes that are happening when your sympathetic nervous system turns on and you start breathing more rapidly. Maybe you're anxious, or maybe you're angry. Those physiological signals that are being sent to your brain, from your body, are a really big part of our experience of emotion.

Donae 4:00

When it comes to emotion and interoception, what do we know? What do we think we know with how those interplay? This, to me, is a new idea: noticing where emotions are in your body and tuning into that piece. Tell me more about that relationship.

Carissa 4:18

I think that there's a few different levels that we can talk about with interoception and its relationship to emotion. I think that you mentioned the first level, which is just recognizing that those cues are happening. I think for a lot of us this is a challenge in and of itself, just attending to a change in your heart rate, or attending to a signal that you're thirsty or hungry.

We know that different individuals have difficulty with this in different directions. Some people may be overly attentive to it. It really impacts them a lot when they feel hungry, or when they have a slight change in heart rate. They are what we might think of as hypersensitive to interoceptive cues.

Then a lot of us really don't recognize these because they're often just playing in the background, and we tune them out in favor of attending to the external world.

A lot of times these things are happening in the background, and they don't really rise to the level of our conscious attention until they get pretty extreme. We just say, "Oh, you know, I haven't eaten in seven hours. I'm all of a sudden, really hungry. I was so wrapped up with what I was doing"

Donae 5:35

This sounds very famiiar. Definitely within the ADHD community, a lot of people have both experiences of the sensory defensiveness externally and then also a lack of attention, or a lack of perception to the internal. Both of those things can be true.

Carissa 5:54

I think that can be true. Both things can be true, even within one individual, depending on the context and type of signal it is. I think that's one of the things that makes this a really difficult thing to study in a scientific way, is just how much variability there is.

Donae 6:12

Right? How do you measure this? Just out of curiosity, how do you study this? How do you measure this?

Carissa 6:18

Yeah, so this is a real challenge, right? Because in other contexts where we're studying sensory processing, we have ways to control the stimulus. We control it with a lot of precision.

If I'm studying hearing, for example, I can play tones at a very precisely controlled volume, frequency. I can really control the nature of that stimulus, and then measure which variables impact people's perception or experience of it. We can't really do that with interception because the stimuli are outside of our control, right?

Donae 6:55

It's inner stimuli.

Carissa 6:57

Yeah. We as scientists have to figure out how we can capitalize on the signals that are already happening. Often, in laboratory tests, what we use for an interception measurement is very focused on the heartbeat, because that is a signal that is always there. It's very consistent. It's really easy for us to record and measure. We can just attach an EKG lead to a person's chest and measure when the signals are happening.

Donae 7:30

So you can measure that, but you can't really measure hunger?

Unknown Speaker 7:33

Yeah, it's much harder to measure those other things, and they're much less consistent. You're always going to have a steady stream of heartbeats. You can try to manipulate people's attention toward or away from and ask them questions about what they're perceiving.

Unknown Speaker 7:49

Whether somebody is experiencing signals from their digestive tract or their urinary tract is going to vary a lot, depending on when they last ate, drank, or other things that we can't really control or measure in the labratory quite as easily.

Carissa 8:06

Right. The research then is pointing to interoception being impacted with autism and with ADHD. Is that true? It's definitely true anecdotally, I don't know if it's true with the research.

Yeah. The research on this is something that's really emerging, because this is something difficult to study. The research has been slow to come out so that we're really still gaining an understanding of this. The paradigms that I just described are where we measure a heartbeat, and then ask people questions about what they perceive, those are lab based experimental paradigms.

There's also other ways that we can measure this construct. A lot of times we just give people a questionnaire measure. We just ask them to talk about in daily life, what their experience is. Do I have the experience where I forget to eat until I'm just about to pass out with hunger? Do I have the experience where the feeling of saliva in my mouth really bothers me?

You can ask a lot of really detailed questions about people's interceptive experience. The nice thing about those questionnaires is that it samples over a large range of their experience. We get data from daily life, which is maybe more relevant than what's happening when you're hooked up to a machine in the lab.

Donae 9:24

That makes sense. Okay, now, as you said that, I'm thinking about how much I'm swallowing saliva...

Carissa 9:29

It's like the pink elephant. Don't think about the pink elephant.


I think I need a sip of water. Hang on. Yeah, so definitely that's a more functional...

Yes, exactly. A more functional, more ecologically relevant way to measure and think about interoception, but it comes with some limitations as well.


People may interpret the questions differently depending on all sorts of things: their education level, their reading level, or prior experiences. Depending on how much some of these things bother them, they may report experiencing it more frequently if they're attending to it more. It's also impacted by people's memories. How much do you remember of your experience of these things over recent months, or weeks?

There's all sorts of things that make questionnaires really helpful in some ways, but also having some limitations in other ways that we just have to think about. All of that to say that we have a lot more data from questionnaire that suggests that all sorts of neurodivergent people have differences in interoception.

Neurodivergent people really report differences on those questionnaires a lot, in terms of their attention to interoceptive cues and their ability to perceive them.

We're not seeing that mirrored in the more experimental lab based work as consistently as we might have expected or hoped. That's a chronic problem with this research that we can maybe get into on another podcast.

Donae 11:06

I do wonder as far as awareness of your heartbeat, maybe we don't want to go down that rabbit trail, but I don't know how aware I am of my heartbeat. Are there some things you're much more connected to on a day to day basis?

Carissa 11:16

Absolutely. I think it depends, there's a lot of individual factors that really affect how much people are tuned into that. As an example, we had a student, when we were setting up some of these experiments in our lab, who was a distance runner.

He was really good at all the experimental tasks where he had to pay attention to his heartbeat, and answer questions about how fast it was beating relative to something else. He was super good at it. Whereas most of the rest of us were thinking, oh, this is hard. It's hard to attend to your heartbeat and feel the signal if you're not actively taking your pulse. People's baseline level of cardiovascular fitness, and all sorts of things really play into it.

Donae 12:00

Well, and that's interesting, too, because when you're saying that, it makes me think, oh, can this be trained? Right? Can you be taught to tune into this more?

Carissa 12:11

Yeah. I think it really can be. I think that's one of the nice things about it is that it's like other sensory systems. Practice makes perfect, right? If we train our minds to focus on these signals, we do get better at perceiving them.

Donae 12:26

Oh, so you know where I'm going with this?

Carissa 12:28

I think I might...

Donae 12:31

All right, tell me: how do we do it.

Carissa 12:35

This has a lot of pretty clear implications for mindfulness activities. The more we're able to focus and perceive these cues: to tune out what is happening in the world around us, to be in touch with our bodies and what our bodies are telling us about how we feel, the more we realize how hard it is at first.

Anybody who's tried to start a mindfulness practice has probably had the experience of, "this is really hard" to just focus on this one thing and keep my mind from being distracted by all the other things that are out there in the environment.

It really is one of those things where practice makes perfect, and your brain is really geared towards being very receptive to that practice. If you're consistent with it, it can really enact changes in the cells at the level of synapses. That can really build and build your skills there.

Donae 13:36

Okay, so what I'm hearing you say is that the practice of this is making it easier, on a brain based level. You are strengthening this wiring, and it's begin to come easier to recognize the signals.

Carissa 13:52

Yeah, exactly. Right. A lot of the treatments that we have in psychiatry and psychology have been demonstrated to change neurons on the level of literally building new synapses. You're literally giving your brain new connections to work with. That is something that has powerful effects to change our behavior.

Donae 14:16

Mindfulness is a big piece of strengthening interoception. That makes sense. When you're talking about mindfulness of emotions, the thing that you do in practice of that is dropping into your body experience and thinking, okay, where am I feeling this anger? Where am I feeling this sadness and kind of connecting to that. We're so used to the thoughts and action about emotion, but the experiencing of a body level that we don't do so much.

Carissa 14:48

That's so true, right? It's very fundamental in our ability to not just experience it, but also to contextualize it, right? One of the things that we're working on in my lab is how we show that there's a going inward where you focus on the interoceptive signals by themselves.

Then there's also going back outward and reintegrating those signals with the world around you, and how your ability to do that can also really impact how you're interpreting your interoceptive experience.

Donae 14:50

Break it down for me. Break it down for me with an example, because this sounds good.

Carissa 15:31

Yeah. I have a graduate student in the lab, Alisa Zoltowski, who came up with this great example to get at this distinction. She gave the example of having the experience of an increase in heart rate and noticing that increase in heart rate.

The first step is that you recognize your heart rate is higher. Then that is really just on the level of interoception all by itself. That's really just getting the heart signal and attending to that, which is huge. That's a great first step.

Donae 16:06

I know that's difficult for many people with ADHD, noticing that.

Carissa 16:10

Yeah, and I think it's difficult for a lot of people without ADHD, too! Just noticing that can be really hard. That's step one.

Then the way Elise describes it, step two, is this contextualization piece where you then integrate your interoceptive information with exteroceptive information. Her example is, okay, I have this increase in my heart rate, where am I? What's around me? If you look around and see that you're in the gym, on a treadmill, your body is dripping with sweat, people on either side of you are jogging, and you notice your heart rate is up, that's probably because I'm exercising.

These external visual signals are helping me to contextualize this. That means, okay, I'm okay. My heart is supposed to be beating faster in this situation. That's expected and actually desirable, given my fitness goals.

If you look around, your exteroceptive information tells you that you're at a cocktail party where you don't know anybody, there's somebody that you would really like to get to know across the room, you're not really sure how to approach them, you feel like your outfit is all wrong, and you are really socially anxious, then you're much less inclined to interpret that same increase in heart rate as okay and acceptable. Being able to integrate the external and the internal really helps us contextualize what the interoceptive signals mean.

Donae 17:42

Are we kind of "looping" here, then? You're at the cocktail party, you have that feeling, you don't think it's okay, and you're seeing this as danger, you're even feeling bad that you're feeling this way... Is it then impacting that heart rate even more?

Carissa 17:57

Yeah, exactly. Right. That's how people might have ended up having something like a panic attack, where become really focused on the physiological experience of anxiety itself.

You start to have anxiety about the rapid heart rate, the rapid breathing, and some of those other sympathetic nervous system signals that you'll get in your interoceptive centers in your brain. That does become a loop.

Donae 18:25

Okay, maybe you have this experience, this racing heart rate, you get your context, you realize it doesn't really fit. Then just tolerating that experience in your body instead of acting on it or judging it, that is a mindfulness practice.

Carissa 18:40

Yeah, I would say so. I think that is a lot of times where some of the higher centers in our brain that have access to all that complicated contextual information can help to modify some of the more evolutionarily older parts of our brain that are really sort of putting our body into fight or flight mode.

It can give us a little bit of acceptance, of, okay, it's normal for me to be responding this way. Also, it's going to be okay. You know, remember last time you were in this situation, you went over and said hello, had a great conversation, ended up walking away with a phone number, and had a great date with somebody.

Your hippocampus, which helps retrieve your stored memories, and your prefrontal cortex, which helps you with higher level planning and recognition of the broader context, can help to keep the more primitive responses of your brain in balance.

Donae 19:41

You're really doing this thought work that's impacting regulation, along with the more body based work that's impacting regulation. It's working together?

Carissa 19:51

There's a yin and yang approach. Both can really be helpful, and they're probably most helpful when they're used in combination.

The immediate situation might not lend itself to a more body focused or mindful approch. It might. You might have a minute where you can just slip away to the bathroom and focus on your breath. If you're in a moment where you have to react quickly or immediately and can't necessarily access some of those tools, then your prefrontal cortex and your hippocampus can help you out in those situations.

Donae 20:30

Right. Okay. With the interoception, usually we're recognizing the signal. That's already tough sometimes. You're contextualizing: the "story" of the signal, and then...

Carissa 20:44

I think then, from there is regulating our response. You know, being able to focus in and realize that we have more control over some of these interoceptive signals than we really know.

Donae 21:00

I want to hear you talk about that.

Carissa 21:03

I think this is probably something that will be really familiar to a lot of your listeners. When you, for example, take some slow, deep, mindful breaths, what you're actually doing with that is engaging your parasympathetic nervous system. This is the good twin to the evil twin of your sympathetic nervous system that gets you all amped up.

These kinds of things have a push/ pull relationship with each other, where one turns on and that turns the other one down. If you can increase your parasympathetic tone, which is what we think of when we do deep breathing, that can directly impact the sympathetic nervous system which is the source of these sometimes distressing interoceptive cues.

Donae 21:54

That breathing is actually bringing you down?

Carissa 21:57

Yes, it's actually having an effect at the level of your nervous system.

Donae 22:01

Okay, so breathing is definitely one for the regulation. What else?

Carissa 22:07

That's a good question. That's the tool that we use the most, right? I feel like that's where we have the most direct lever to impact the system.

There are other things where you can limit the amount of things that you have to attend to. Even something as simple as closing your eyes, and sort of shutting down the visual input for a little while, so that you can kind of focus more on the internal input and kind of getting that under control, that can be really helpful to just sort of giving your brain a little less to deal with.

Donae 22:38

I've actually used that example. I know, we didn't talk about this, but I've used that example before. Just getting less visual feedback, for me, has been really centering, and helps me calm down, even energize at times when I'm feeling really overwhelmed, overloaded. It can be restorative.

Carissa 22:55

Yeah, yeah, absolutely. I think sometimes just that sense of overwhelm can really respond well to just shutting down channels of input.

Donae 23:06

Yeah, yes. is less is more.

One thing that I noticed a lot in myself and people I work with, is that often our pace, our attention, we're very busy, and not tuned into our bodies. I've heard people talk about this. I've had somebody talk about intuitive eating, talk about even scheduling eating, which doesn't sound very intuitive eating, but because that tends to be a breakdown, that might be helpful.

Carissa 23:34

Yeah, I think just sort of giving yourself opportunity and more opportunities to recognize those cues, when they're happening, can probably be really helpful. And for some people that is sort of like scheduling scheduling some time where you check in, you know, you're gonna check in and say, am I hungry? Am I thirsty?

Donae 23:52

That's a good point, scheduling a check in, because it never, for some of us, feels very urgent or even makes it on our radar.

Carissa 24:00

Right. Yeah. A lot of times, it just feels like something that you can do after you've done all these other really important things. Then you end up getting so focused on all these things that feel so important that you can really neglect that bodily side of yourself for a long time.

Donae 24:19

Like thirst, hunger....I'm feeling woozy.

Carissa 24:23

Yeah. Right. Yeah, in front of the laptop for you know, six hours without moving. Maybe it would be good to get up and walk around for a few minutes

Donae 24:36

It's a struggle. Once I am in the zone, I don't want to break it.

Carissa 24:38

Exactly. Right. It's not always easy to get there, so it can be tough to give it up.

Donae 24:43

Yeah. This definitely has implications for ADHD, when it comes to impulsivity, right? Because I think a lot of times we are disconnected from our physical experience of an emotion until it's just right at the front door.

It's like, right there. And then it's so much more difficult to not just react, respond in that moment. It's already such a high level of input at that point.

Carissa 25:08

Yeah, right. It's almost like you've kind of, in some ways missed the opportunity to really intervene on it.

Donae 25:15

I've even noticed how just tuning into my emotion on a body level, how regulating even just acknowledging, "That really hurt my feelings" is. Just noticing the feelings: in my throat, a swelling in my throat, this weight in my throat, this sinking is thinking in my stomach. Something about that is so helpful.

Carissa 25:32

Yeah, yeah, I think that's, that's really true. It just, it just gives you like an anchor almost, you know.

Donae 25:39

Absolutely, like an anchor. It's very easy (to get carried away by) the whole story of an emotion, the whole story of what's behind the emotion. Whether I'm right or wrong, what has happened. It almost carries you away.

When you're going back into that body experience, it's an anchoring. It's just focusing on how it's showing up. For me, it tends to be very regulating.

Now it does. It didn't initially. At first it was like, "This is dumb", right? But now it's helpful. I was mindfulness resistant, like most of the people that I work with. No, I was no different. Yeah, probably worse.

Carissa 26:16

Same. And I'm still, I really can't say that I'm still all that good at it.

Donae 26:21

It'sa practice, I don't think any of us are.

Carissa 26:25

Yeah, I think that's exactly right. Just sort of like accepting that that's the case, and that it's okay, you know? And that the value is in the consistent practice, that is how you get better at it. That's also how you train your brain to use it in a way that can be effective in regulating emotions.

Donae 26:44

Right. Any kind of regulation tool, for us, is gold.

Carissa 26:48

Yeah, yeah. And what I like about focusing on it is that you do kind of have this two-pronged approach that you can take. You can sort of focus on the cues themselves and that experience itself, which you might do in mindfulness, just really being present with the physical feeling.

But then you can also exercise that prefrontal part of your brain that helps you give context and interpretation to what your feelings mean in the context that you're in and draw on your memories of similar feelings and experiences. That's another thing that is very different (than mindfulness), but also improves with practice.

Donae 27:32

Thank you so much for being my sister and being on my podcast and breaking down some interoception. It's good to know about this, how it impacts our function, how we can work with this, and just kind of get up to speed. So thank you.

Carissa 27:48

It's my pleasure. I really enjoyed chatting about it.


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