"He came back and was still autistic but his autism had quieted down and now it comes out more as a charming quirk," he said. "Now he is conversational, he's in school."
Isaacson said that Rowan attends a home school for kids with special needs, rides horses every afternoon and still participates in more traditional therapy.
But Dr. Paul Offit, a professor of pediatrics at the University of Pennsylvania and the author of "Autism's False Prophets: Bad Science, Risky Medicine, and the Search for a Cure," said he has some concern that other parents may become too hopeful after hearing about Isaacson's experience.
"For disorders like autism, where there isn't a clear cause or cure, I think there is a very strong desire by parents to want to do something," said Offit. "And I think this book fills that need."
According to The Centers for Disease Control and Prevention, in 2007 one in every 150 8-year-olds had an autism spectrum disorder.
"The problem is that I think false hope is a bad thing because one can get exhausted or divert resources that could go to methods that will have empirical evidence that it works, like behavioral therapy," said Offit.
The Autism Society of America has already come out and said they hope to see more research on equine therapy.
Offit said he would advise parents to have a "healthy degree of skepticism" on the therapy.
For example, Offit reminds that it's proven that children with autism tend to be at their worst between ages 2 and 5 and tend to improve between ages 5 and 10, which is when Rowan took his trip to Mongolia.
The Autism Society of America, which openly supports and promotes "The Horse Boy," reports seeing an uptick in the number of parents looking into equine therapy in recent years, even despite the lack of scientific research into its effectiveness.
"We're very hopeful that families who read this story will learn about sensory therapy and seek their own adventures," said Marguerite Kirst Colston, the vice president of constituent relations at the Autism Society of America.
"It's becoming more and more popular, so it must work to some extent," said Colston. "In the past two years we've seen more and more equine therapy programs popping up across the country."
"Children with any medical condition that has sensory issues like autism does relate with animals because animals, by nature, are sensitive," said Colston. "I think that as long as families are seeing something that is benefiting their child, then this sort of therapy is good."
"Is it causation or correlation I don't know, but the point is that the child is happier and getting better," she said.
Dr. Katherine Loveland, the director of the Center of Human development Research at the University of Texas Medical School in Houston, said that she believes equine therapy to be a good supplement to tradition therapies for autism.
"[Equine therapy] is not a primary treatment for autism but it could be a useful adjunct treatment for kids," said Loveland. "There is a lot of anecdotal evidence that it can have a number of positive effects."
Loveland said often times horses are a valuable tool to getting a child with autism to calm down enough to even be able to process new information.