Horse-riding can help put autistic children on the road to recovery.
Hippotherapy is a medical treatment that uses horses and is supervised by a licensed speech-language pathologist.
"People perceive it's the interaction with the horse that's making the change. However, the movement of the horse is extremely powerful, and it's that movement that's having neurological impact on the autistic child," said Ruth Dismuke-Blakely, an expert from New Mexico.
According to preliminary analysis of an ongoing study by Dismuke-Blakely, hippotherapy has been shown to increase verbal communication skills in some autistic children in as little as 18 to 25 minutes of riding once a week for eight weeks.
"We see their arousal and affect change. They become more responsive to cues. If they are at a point where they are using verbal cues, you get more words," Dismuke-Blakely told CNN. "It's almost like it opens them up. It gives us access."
She cautions that a horse's movements can be powerful. For some autistic children, riding too long can overstimulate their nervous system, leading to more erratic behavior.
But Rupert Isaacson and Kristin Neff, a Texan couple, report that horse-riding has proved of immense benefit to their son Rowan.
Trekking across the Mongolian prairie on horseback, Isaacson says, Rowan's behavior was changed dramatically.
"It's the oldest horse culture on the planet. Everyone still gets around on a horse there -- so a nomadic culture. The word 'shaman' comes from there," Isaacson said, explaining his decision. "I just thought, 'Well, what if we went there and rode across the steppe and visited traditional healers? You know, what might happen for Rowan? Might there be some positive outcomes?' "
Isaacson credits Rowan's improvement to horses and time in nature -- and to shamanic healing, which he says he simply can't explain rationally.
Isaacson has written a book, "The Horse Boy," about Rowan's autism.
"Rowan was not cured of autism out there," Isaacson stressed. "The word 'cure' is not in my vocabulary for this. Rowan came back without three key dysfunctions that he had. He went out to Mongolia incontinent and still suffering from these neurological firestorms -- so tantruming all the time and cut off from his peers, unable to make friends -- and he came back with those three dysfunctions having gone."
His parents never abandoned more orthodox treatments for his autism either. Rowan's applied behavioral analysis therapist has him studying math and English at the third-grade level -- a full year ahead of some of his peers.
"He's just becoming a very functional autistic person," Isaacson said.