For military members, zoning out can be a good thing. There are benefits to ignoring hunger pangs on a long mission or a racing heart during a tense battle. Over the long term, though, overlooking physical and emotional sensations can increase the risk of a variety of mental health disorders, including suicidal thoughts.
“For soldiers, being able to ignore pain or fear can be adaptive. It’s something that’s promoted in the military, both implicitly and explicitly,” says April Smith, PhD, an assistant professor of psychology at Auburn University. “But outside the short window of a mission, it’s important for people to be aware of their bodily sensations.”
In her Research on Eating Disorders and Suicidality Lab, Smith studies interoception, the awareness of body sensations. With funding from the Department of Defense, she is exploring an intervention to improve interoception to reduce the risk of suicide, eating disorders, and other negative outcomes, both in service members and civilians. Smith talked with the Monitor about the importance of better understanding this underappreciated sixth sense.
What does interoception entail?
Interoception is the ability to be aware of internal sensations in the body, including heart rate, respiration, hunger, fullness, temperature, and pain, as well as emotion sensations. Many people consider interoception to be an additional sense that is critical to the way we understand how we feel on a moment-to-moment basis.
You can think of someone with “good” interoception as the person who feels themselves getting hungry and gets a snack, or who feels their heart racing and takes some deep breaths. A person with low interoception, conversely, might go all day without eating. But evidence suggests that having high or low interoception in one domain doesn’t mean you’re good or poor in interoception overall. Someone might be good at recognizing hunger sensations but poor at recognizing emotions, for example.
How does interoception affect mental health?
The earliest studies of interoception and mental health showed that being too aware of internal sensations, such as heartbeat, can contribute to anxiety disorders. There’s also a robust literature linking interoceptive dysfunction to eating disorders. Not being aware of hunger sensations can facilitate restrictive eating, and if you’re not aware of fullness sensations, that could contribute to binge eating.
Research on interoception has skyrocketed in the past couple of years, and people are now finding links with all kinds of disorders, including depression, obsessive-compulsive disorders, trauma disorders, substance use, and suicidality. It seems to be a transdiagnostic risk factor for a lot of mental health conditions.
What’s known about the mechanism?
We still have a lot of unanswered questions. There are so many components of interoception, and different deficits might be related to mental health outcomes in different ways. We have some evidence to suggest that being worse at understanding pain sensations is a better predictor of self-injurious behavior than having poor interoception for heartbeat or cardiac sensations. It’s likely not just one’s awareness of the sensations that matters, but also the cognitive appraisal of those sensations.
There’s also a lot we don’t know about what interoception looks like over time. Is it a bidirectional relationship, where a predisposition to low interoception might contribute to a mental health disorder, but then that disorder exacerbates interoceptive dysfunction, leading to a kind of feedback loop? Two of my former students, Lisa Velkoff, PhD, and Lauren Forrest, PhD, have started longitudinal research to explore that question.
What’s exciting to me is that interoception is clearly modifiable. And if interoception does turn out to be a transdiagnostic risk factor, then incorporating interoceptive interventions into existing treatments could do a lot to improve a variety of mental health outcomes.
What does your research show about targeting interoception to improve mental health?
In collaboration with colleagues including Air Force Lieutenant Colonel David Tubman, PsyD, ABPP, and Major Aaron Esche, PhD, at Wright-Patterson Air Force Base, and Lieutenant Colonel Michael Dretsch, PhD, at the U.S. Army Medical Research Directorate-West, my lab developed an intervention called Reconnecting to Internal Sensations and Experiences (RISE). It’s an online intervention consisting of four 30-minute modules designed to increase connection with the body. The training consists of psychoeducation, self-guided reading, interactive writing prompts, and some out-of-session practice people can do at home to build on the skills they’re learning. We introduce people to interoception, then teach a variety of concepts including progressive muscle relaxation, thinking of the body in terms of function rather than appearance, noticing and managing emotions and their associated physiological sensations, and intuitive eating.
In an uncontrolled pilot study of 22 people seeking treatment in an outpatient mental health clinic, we found that RISE was associated with improvements in several facets of interoception, as well as decreases in depression and anxiety symptoms and significant decreases in suicidal ideation (Behavioral Therapy, Vol. 52, No. 5, 2021). In a second pilot, among university students, we again found that RISE was associated with improvements of some aspects of interoception, and decreases in suicidal ideation and eating disorder symptoms (Brain Sciences, Vol. 12, No. 2, 2022).
Now we’re finishing a randomized controlled trial of 195 service members, randomly assigned to RISE or a comparator condition that focused on general healthy habits. We found that RISE was associated with improvements in six out of eight facets of interoception relative to the control group. And those improvements persisted at the 1- and 3-month follow-ups.
What’s next for your lab and interoception research more broadly?
We want to continue testing and improving RISE. We’re modifying it to make it more relevant to people with eating disorders, and I’m working on another project testing it in veterinarians—a population with an elevated rate of suicide compared with the general population. Veterinary training is reminiscent of military training; veterinarians are taught to ignore internal sensations during surgeries or when performing euthanasia. We’re studying whether that could be contributing to the increased rate of suicidal behaviors in this population, and whether RISE could improve those outcomes.
I’m also hoping the field can improve measurement of interoception so we can better understand what specific types of interoceptive dysfunction are related to specific mental health disorders. I doubt it’s as simple as people having “good” or “bad” interoception. More likely, it’s about being able to tune in or tune out when it’s appropriate. Tuning out can be adaptive, as we see with service members. But people need to be able to recognize when to tune back in.
