Children's Hospital Colorado

Getting to the Bottom of "Tummy Troubles"

A toddler boy lies on a table while a doctor examines his stomach.

In the past, children who suffered from unexplained stomach distress often had to learn to live with issues such as chronic stomach pain or nausea. After inconclusive tests, doctors would reach the end of the road – managing symptoms was one of the only options.

Now, finally, these kids might have some answers.

The answers lie in the emerging field of the “second brain,” or the millions of neurons (nerve cells) that live in the gastrointestinal (GI) tract. When functioning properly, these nerves gather vital information and send it to your brain. They can tell your brain if you’re full or hungry, if you need more water or if your body has enough zinc.

Why stomach neurons might not work correctly

Stomach neurons can malfunction for any number of reasons: a past illness such as a stomach virus, a chronic condition like celiac disease or an imbalance of the bacteria in your GI tract. If they do malfunction, they can give the brain the wrong information by firing a faulty signal. For example, you might feel pain even if your doctor hasn’t detected any reason for pain.

Everyone will experience injury to their GI neurons at some point, and most will recover. New evidence suggests that stem cells in the gut can grow new neurons to replace the damaged ones, similar to how it happens in the brain. But some people have challenges replacing damaged neurons, though physicians are not sure why.

Jaime Belkind-Gerson, MD, pediatric gastroenterologist, Director of the Neurogastroenterology and Motility Program, and “second brain” expert at Children’s Hospital Colorado, is trying to find more precise answers.

“The diagnosis that something’s wrong with the ‘second brain’ can be challenging,” he says. “We have to make sure there’s nothing that would otherwise explain the symptoms, such as a bug, or colitis or food allergy. Everyone is a little bit frustrated because the GI doctors usually say, ‘We can’t find anything wrong.’”

How doctors might treat a “second brain” problem

Dr. Belkind-Gerson is often the seventh or eighth doctor a child sees when they have a digestive challenge. He starts by listening to the patient’s story and symptoms to establish if the child may have a “second brain” problem.

Though there is not yet a test to determine a problem with gut neurons, Dr. Belkind-Gerson can conduct a clinical evaluation, which he sometimes combines with motility testing, to get better understanding of the problem. He can then prescribe a personalized treatment to try to repair the neurons.

“We’ll start with lifestyle changes first,” Dr. Belkind-Gerson says. “We’ll have them work on better sleep, lowering anxiety, getting exercise — things which will often be reflected in gut symptoms.”

The link between the “second brain” and emotions

If symptoms don’t improve with these lifestyle changes, he then considers medications. He might prescribe those that increase serotonin, a vital neurotransmitter in both the second and first brain.

Serotonin is most commonly known as an antidote to depression. “It’s our happy neurotransmitter,” Dr. Belkind-Gerson says. But, he points out, serotonin has many other functions, like moderating immunity, inflammation and motility. When this neurotransmitter malfunctions, it can cause all sorts of problems.

95% of serotonin production takes place in the gut.

“We found out not long ago that sometimes people who are depressed, if you give them medication that raises the serotonin level in their body, you improve their GI symptoms as well,” Dr. Belkind-Gerson says.

He’s careful to point out that this treatment only applies to a small number of kids. When he does prescribe a serotonin-increasing medication, he does so with a multidisciplinary team that includes psychiatrists and psychologists.

What’s next for the “second brain”

Because the “second brain” is a new field, diagnosis and treatment of “second brain” problems are still evolving.

For now, Dr. Belkind-Gerson recommends keeping kids active — which helps with movement in the gut and sensory function — as well as eating a balanced diet and minimizing stress to support GI health. Though lifestyle changes are difficult to implement, “They’re well worth it to keep our ‘second brain’ happy,” he says.

And for the long term?

“I think we’re going to find out a lot in the coming years. We — and others — are working hard in our labs to figure this out,” Dr. Belkind-Gerson says. “At some point, we will be able to precisely diagnose a neurotransmitter or bacterial abnormality, treat patients individually, and get their gut back to proper balance.”

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