"The data on early exposure and long-term exposure in kids, at least one study suggests small decreases in IQ long term," said Mitch Earleywine, a psychologist and associate professor at the University at Albany who has researched marijuana and currently serves on the advisory board for NORML.
"My only concerns are based on those data of deviant brain development or loss of IQ points, but again, we're talking about someone who is autistic, so I'm not sure how nuts to go about that," he said.
Noting that he only infrequently hears about parents using it for their children's autism, Earleywine said, "My friends who are big in autism treatment, this is not reaching them at all. The news doesn't reach them and they think little of this approach," he said, explaining that many doctors who work with autistic children prefer to use behavioral therapy instead of pharmaceutical intervention.
"I prefer to see people really go with the behavioral treatments as the first line," he said. However, he understands why a parent might choose to give a child marijuana to treat autism symptoms.
"The day to day life with an autistic kid is really difficult to understand," he said. "Having some kind of intervention like this can mean the different between someone's going inpatient or not."
Referring to a Rhode Island mother who wrote about her experience with pot in the online magazine Double X, Earleywine said, "I hope other folks don't give her too much trouble until they've walked a mile in her shoes."
By giving the marijuana to the child in food, parents may avoid some of the negative side effects of smoking, said Earleywine. And while marijuana may be available in pill form, he explained that that is probably not an appealing option.
For one thing, he explained, the pharmaceutical forms of THC -- an active component of marijuana -- available may not have all the benefits that marijuana itself does, and the pills can be expensive as a treatment, since they can range, Earleywine said, from $4 to $11 each, with a child needing three per day.
Meanwhile, he said, it seems a child's dose from growing the drug in-home was probably around $1 per day.
While some parents who have used marijuana for autism may swear by it, it remains rare and unstudied, at least on any significant scale.
"I'm not aware of any research on the efficacy of marijuana on the treatment of autism," said Stephen M. Edelson, director of the Autism Research Institute, which collects information from parents on alternative treatments they try. "That doesn't mean it doesn't work, it just means there's not scientific documentation that it does work."
"We still hear reports from parents who have tried it. I cannot say that everyone who tries it sees a change," he said.
"As far as research, no there isn't and I would think there should be," said Edelson. "That could be one of the few options to treat children who have these very severe behaviors."
But while parents have tried a variety of treatments for autism, the common thread may be the calming effects these treatments have, rather than anything about the treatment itself.