"Adam is a very slow processor and deep thinker and has an incredibly divergent brain going a thousand miles an hour all the time," she said.
For many years, he was treated by a well-respected pharmacologist and a therapist, according to Johnson. But prescription medications were not working well enough, and by the time he was 14, his family turned to integrative medicine looking for a "broader range of tools." His urine and blood tests found a bacterial imbalance.
"I don't want to bad mouth drugs -- they have a place," said Johnson. "But I think there's more to learn."
Last year, he was taken off all medications, put on a special diet and treated with probiotics. "Friends, family and his teacher were amazed," said his mother.
Today, Adam is in honors classes, playing clarinet in the band and doing well. "It's been a real triumph," she said.
Another Virginia 10-year-old was treated with probiotics after being incorrectly diagnosed with PANDAS after he developed compulsive symptoms following a strep infection and a lengthy course on antibiotics.
"He had no gut flora," said his mother, Robin, who did not want to use her last name. "He had been healthy and athletically coordinated and then developed these compulsive behavior and tics. It didn't seem like it was in his control."
After probiotics, "it was like night and day," she said. "His symptoms went away and he was totally fine. If we had kept him on antibiotics, it would have eroded his system."
But many are skeptical of these "N of 1" stories -- single clinical cases without controlled studies.
"My first reaction is that, frankly, this is just too simple," said Nancy Desmond, program officer at the National Institute of Mental Health. "And there are so many things we don't understand. We don't know for sure which microbial species are part of the microbiome."
"These are interesting questions that we don't know much about at all," she said. "Most of the studies are very descriptive and suggest correlations, but we need to be cautious."
Desmond said there had been several "provocative observations" at NIH's Human Microbiome Project and in other countries. "More people are thinking about how [the gut] talks to the brain."
She said that NIMH is encouraging studies to address the mechanisms of gut bacteria and their association with mental health functions.
"We are really trying to encourage people to develop experiments and address the fundamental question of how bacteria influence the development and function of the brain," said Desmond.
"We are also talking about viruses and not just bacteria and the complexity of their interactions. It's really very tantalizing for science in general and an interesting and potentially exciting frontier for studies."