A Pediatric Psychologist on the Gut, the Nervous System, and the Whole Child
By Dr. Lienna Wilson, Licensed Psychologist | Vagus Vitality
Most parents who find their way to Dr. Sam Scarnato have already done a great deal. There have been therapists and specialists, behavior plans and medical visits, and often real improvement, at least for a while. Then the stomachaches return, the sleep falls apart, or a new symptom appears, and the same question comes back: how does all of this fit together?
Dr. Scarnato, a pediatric functional nutrition and mental health practitioner and the founder of Belief in Joy, has spent more than twenty years working with children and families. Her approach brings psychology together with physiology, nutrition, nervous system regulation, daily rhythms, and relationships. I asked her what first led her to look at the gut, how the vagus nerve fits into a child's mood and digestion, and where an overwhelmed parent can realistically begin. Her answer to that last question may come as a relief: before changing anything, start by noticing.
When Progress Doesn't Hold
Dr. Scarnato's curiosity about the gut began with a pattern she couldn't ignore. “The longer I was in practice, the more complex the cases became,” she says. “Kids were showing up with two or three diagnoses at once (ADHD, autism, OCD, anxiety, tics) while also dealing with physical problems, like constipation, headaches, stomachaches, and sleep issues.”
The families she saw were not short on effort. Parents were doing “all the things,” she says: “therapy, speech, OT, medical visits, medications, behavior plans.” Symptoms sometimes improved. “Then the kids would end up back on my schedule, with new symptoms or old ones returning.”
She knew parents deserved more than another round of the same approach. “I knew there had to be a better answer for parents than just, ‘Let’s try a different protocol,’ or worse, ‘Let’s do the same thing again and hope this time it sticks.’” At the time, she admits, “I didn’t know what the answer was just yet.”
A Turning Point at Home
The answer began to take shape in her own family. Her son developed what she describes as “an unusual set of symptoms”: digestive issues, a rash, constant urges to urinate that kept him running to the bathroom day and night, poor sleep, trouble focusing, motor and vocal tics, meltdowns, trouble hearing, and intense cravings for salt and sugar.
The family moved from pediatrics to dermatology to ENT, and finally to a nephrology referral. “We were getting nowhere,” she says, “until I started researching all I could about digestion, immune stress, and nutrition. These weren’t things anyone on his care team talked to us about.” What followed was a long process of experimenting with food and supplemental support. “There was so much trial-and-error involved. It took time, but eventually his symptoms resolved.”
That experience reshaped her clinical work. “This experience changed the questions I was asking about the kids in my practice,” she says. She began looking more closely at the connections between digestion, inflammation, nutrition, and mental health, and it sent her back into training in physiology and nutrition.
The Gut, the Brain, and the Immune System
When Dr. Scarnato explains the gut-brain connection to parents, she keeps it simple. “The gut and brain are constantly influencing each other, which is why I don’t separate what’s happening in your child’s body from their mood or behavior.”
Researchers describe this relationship as a two-way communication system: the brain shapes digestion, and signals from the gut can in turn affect emotion, motivation, and thinking (Mayer, 2011). Dr. Scarnato adds a twist from functional nutrition. “We don’t say you are what you eat,” she explains. “Instead, we emphasize that you are ‘what your body can do with what you eat.’”
Inflammation is a key part of that picture, in part because the intestine holds the largest share of the body’s immune cells (Rivera & Lennon-Duménil, 2023). “When digestion isn’t working well or inflammation is present,” she says, “the signals traveling between the brain, gut, and immune system can influence the way your child thinks, feels, and behaves.”
Where the Vagus Nerve Comes In
The vagus nerve is one of the main routes for this conversation between gut and brain, and Dr. Scarnato points to its role in digestion itself. “The vagus nerve helps regulate how quickly and effectively food moves through the digestive system,” she says. The gut has its own extensive network of nerves, called the enteric nervous system, but it works in coordination with the brain, which sends signals to the gut through vagal and other pathways (Furness, 2012).
Because that connection runs in both directions, stress matters for digestion. “Our nervous system is continuously responding and adjusting to what’s happening both inside of us and around us,” Dr. Scarnato explains. “When a child is feeling stressed either frequently or for longer periods of time, digestion can be affected, because the gut and brain are in communication with each other.”
The vagus nerve also links the nervous system to inflammation. Neurosurgeon Kevin Tracey and his colleagues found that signals traveling along the vagus nerve can dampen the body’s inflammatory response, a protective circuit he named the inflammatory reflex (Tracey, 2002). Much of that early work comes from animal studies, and how it plays out in children’s everyday health is still being explored. Still, it helps explain why Dr. Scarnato considers digestion, inflammation, and nervous system state together rather than one at a time.
Symptoms Offer Clues, Patterns Reveal Priorities
Dr. Scarnato’s approach draws on psychology, physiology, nutrition, nervous system regulation, daily rhythms, and relationships, but she doesn’t treat them as separate categories. “I don’t think of these pieces as separate from each other,” she says. “For example, a child who isn’t sleeping well will likely be more emotionally reactive during the day. A child who is feeling uncomfortable due to constipation may have a harder time concentrating or handling feelings of frustration.”
Research points to that connection between gut comfort and emotional well-being. In a school-based study of more than 900 adolescents in Sri Lanka, those with functional constipation scored higher on measures of anxiety and depression, attention problems, withdrawal, and social problems than their peers, and these difficulties were tied to lower quality of life (Rajindrajith et al., 2020). Because the study captured a single point in time, it can’t say which came first, but it fits what Dr. Scarnato sees in her work with families.
The list of influences she considers is broad. “What a child eats, how their body digests what they eat, how a child moves throughout the day, the types of demands being placed on them, and even what’s happening within their relationships with others can all affect how a child is feeling and functioning.”
Things tend to get out of balance, she says, “when we focus on the most visible symptom, usually involving behavior or mood issues, without stepping back to consider what else may be contributing.” She sums up her philosophy in two short sentences: “Symptoms offer clues. Patterns reveal priorities.”
Daily Rhythms and the Ability to Adapt
For Dr. Scarnato, daily rhythms are simply “a family’s everyday habits involving sleep, movement, nutrition, stress, and social connection.” What interests her is less any single day than the pattern over time. “I want to look at patterns regarding what these habits look like for a child not just in a day, but day after day after day.”
She frames those patterns as a series of shifts a child moves through. “How well is a child shifting between activity and rest? Hunger and fullness? Independence and connection? Stress and recovery?”
The goal is not a child who is calm all the time. “Rather than striving for a perfectly regulated child, we engage in the daily habits that promote an ability to adapt.” That view reflects a broader understanding of nervous system health as flexibility: the capacity to meet a challenge and then return to rest, rather than staying in one state no matter what the day brings.
Regulation Happens in Relationship
Children often borrow a sense of steadiness from the adults around them, and Dr. Scarnato sees parents as central to that process. “Parents are the most consistent presence in a child’s life,” she says. “But that doesn’t mean that we as parents must always be ‘perfectly regulated’ in order to help our children.”
What matters more, in her view, is what happens around the hard moments. “Our kids get to see us when we’re feeling joyful, frustrated, overwhelmed, uncertain. It’s not the feelings that make the difference. What we do when our feelings are intense and uncomfortable and how we engage with our children afterwards is where it counts.”
She offers parents some welcome reassurance. “It would be unrealistic to say healthy parent-child relationships always require two well-regulated people. We as humans are so much more forgiving than that!” The aim instead is “a relationship where both people, child and parent, can have big feelings without permanently ruining the connection.”
There is evidence that connection and vagal health are linked. In one study, adults who built more positive emotions through a loving-kindness meditation practice showed increases in vagal tone, and that change was explained by how socially connected they came to feel (Kok et al., 2013). The research was done with adults rather than children, but it supports the larger idea Dr. Scarnato brings to families: feeling connected is part of how a nervous system finds its footing.
Where to Start: Observe Before You Change
For parents who want to support their child’s gut and nervous system but feel overwhelmed, Dr. Scarnato’s first step may come as a relief: don’t change anything yet. “When parents are feeling overwhelmed, I don’t want them to change anything right away,” she says. “First, I want them to observe.”
To make that easier, she created a free resource, The Missing Framework Observation Tracker. Parents use it for one to two weeks, noting their child’s sleep, mood, behavior, energy, body, and digestion each day, then stepping back to reflect on what tends to show up together, what seems better on good days, and what seems worse on tough ones. The tracker’s own examples give a sense of what to look for: trouble falling asleep on school nights alongside more irritability, or bedwetting alongside stomachaches.
“When you recognize the patterns,” she says, “it becomes much easier to see what deserves your attention first.”
Dr. Scarnato’s work offers a gentle reframe for parents who feel they have tried everything. A child’s mood, behavior, digestion, and sleep are not separate problems to be solved one at a time, but connected signals from one body and one nervous system. Seeing that pattern clearly, and starting with observation rather than another round of changes, may be the most useful step a family can take.
About Sam Scarnato, PsyD, FNLP, CFNC
Dr. Scarnato is a pediatric functional nutrition and mental health practitioner and the founder of Belief in Joy. With more than twenty years of experience working with children and families, she helps parents connect the dots between their child’s mood, behavior, and physical health, so they can better understand what deserves attention first. She works with parents and families in New Jersey and beyond. Learn more at beliefinjoy.com or subscribe to her Substack, The Missing Framework.
Note: The information in this article is for educational purposes and is not a substitute for individualized medical or mental health care. Children with persistent digestive, sleep, or behavioral symptoms should be evaluated by a qualified clinician, and changes to a child’s diet or supplements are best made with professional guidance.
References
Furness, J. B. (2012). The enteric nervous system and neurogastroenterology. Nature Reviews Gastroenterology & Hepatology, 9(5), 286–294. https://doi.org/10.1038/nrgastro.2012.32
Kok, B. E., Coffey, K. A., Cohn, M. A., Catalino, L. I., Vacharkulksemsuk, T., Algoe, S. B., Brantley, M., & Fredrickson, B. L. (2013). How positive emotions build physical health: Perceived positive social connections account for the upward spiral between positive emotions and vagal tone. Psychological Science, 24(7), 1123–1132. https://doi.org/10.1177/0956797612470827
Mayer, E. A. (2011). Gut feelings: The emerging biology of gut-brain communication. Nature Reviews Neuroscience, 12(8), 453–466. https://doi.org/10.1038/nrn3071
Rajindrajith, S., Ranathunga, N., Jayawickrama, N., van Dijk, M., Benninga, M. A., & Devanarayana, N. M. (2020). Behavioral and emotional problems in adolescents with constipation and their association with quality of life. PLOS ONE, 15(10), e0239092. https://doi.org/10.1371/journal.pone.0239092
Rivera, C. A., & Lennon-Duménil, A.-M. (2023). Gut immune cells and intestinal niche imprinting. Seminars in Cell & Developmental Biology, 150–151, 50–57. https://doi.org/10.1016/j.semcdb.2023.01.006
Tracey, K. J. (2002). The inflammatory reflex. Nature, 420(6917), 853–859. https://doi.org/10.1038/nature01321