Dr. James Greenblatt, a Boston-area psychiatrist, had a puzzling case: a teenager arrived in his office with severe obsessive compulsive disorder (OCD), as well as attention deficit hyperactivity disorder (ADHD) and an array of digestive problems.
"Mary's parents had been running around for many years and she'd had a poor response to medicine," said Greenblatt, founder of Comprehensive Psychiatric Resources Inc. in Waltham, Mass. "When a patient doesn't respond, that's a red flag."
Greenblatt first did a simple urine test for the metabolite HPHPA, the chemical byproduct of the clostridia bacteria, and found that it was elevated. He put her on a course of high-powered probiotics to boost her good bacteria, followed by antibiotics, and her levels began to "dramatically" go down, he said.
After six months, Mary's symptoms began to disappear. And by a year, they were gone. Today, three years later, Mary is a senior in high school and has no sign of either mental disorder.
Greenblatt, like many others, are beginning to recognize the power of healthy gut bacteria. The average adult carries up to five pounds of bacteria -- trillions of microbes -- in their digestive tract alone.
A recent study in the journal Science showed that thin and fat people have different bacteria -- a discovery that could lead to weight-loss programs. Doctors have also been using fecal transplants to seniors when their gastrointestinal health is compromised in nursing home living.
And now, scientists think there may be a link between what's in your gut and what's in your head, suggesting that bacteria may play a role in disorders such as anxiety, schizophrenia and autism. In some patients, the strep bacterium has been linked to OCD in a condition known as PANDAS.
A study published in Nutritional Neuroscience from The Great Plains Laboratory, has shown that HPHPA levels are much higher in the urine of autistic children. Those treated with antibiotics effective against the bacteria clostridia show a decrease in symptoms.
Babies are born with a sterile digestive tract and first acquire their bacteria while traveling through the birth canal. They get more in breast milk and in the world outside the womb through contact with other people.
Scientists are so far unable to identify every strain of bacteria, but they can test for the chemical byproducts that they produce, according to Greenblatt.
He said he checks every patient for HPHPA with a simple organic acid urine test before moving ahead with medications to treat symptoms.
"Eight out of 10 people are fine," he said. "But in the two patients where it's elevated, it can have profound effects on the nervous system."
"I don't know why this test isn't done on every psychiatric patient," he said. "I question that every day."