July 19, 2005 -- Secretin, a digestive system hormone, may not be the hoped-for answer to autism, researchers report in The Cochrane Library.
The finding doesn't come from a new test. Instead, it's based on a review of 14 past studies.
The studies included a total of 618 children with autism and related disorders.
"There is no evidence that single or multiple dose intravenous secretin is effective, and as such it should not currently be recommended or used as a treatment for autism," write the researchers.
About the Report
Researchers working on the review included Katrina Williams of Children's Hospital at Westmead in Australia.
The studies lasted three to six weeks. Measurements included core features of autism, communication, behavior, visual-spatial skills, mood, and side effects.
Each study was designed differently. Some didn't check all of those measurements. Some just tested secretin; others compared secretin with a fake drug (placebo).
"There is no evidence to suggest that a single dose of intravenous secretin should be made available to all children with autism spectrum disorders," write the researchers.
"It also seems unlikely that multiple dose therapy is effective, although the full report of the largest multiple dose study is not available yet."
No serious side effects were reported.
However, "the risk to a child of serious side effects is likely to increase with repeated doses and more adverse events are likely to be reported if secretin is made widely available," write the researchers.
Secretin and Autism
WebMD contacted Jenifer Lightdale, MD, MPH, of Children's Hospital Boston for her views on the report.
Lightdale is a pediatric gastroenterologist. She worked on a study of secretin and autism published in the November 2001 issue of Pediatrics.
That study found no language and behavior benefits of secretin treatment in 20 autistic children treated for five weeks.
Secretin is FDA-approved for treating pancreatic insufficiency, but not autism, says Lightdale.
"Those of us involved initially in looking at secretin obviously got caught up in the euphoria that possibly there was a treatment for autism," Lightdale tells WebMD.
"Very quickly, I think those of us skilled in science crashed. It was clear that there probably wasn't a relationship between secretin and improvements in autism," says Lightdale.
"There continue to be investigations, but these investigations haven't been standardized. That's a big issue with any research happening in autism," says Lightdale.
"Following the general guidelines of doing a good clinical trial will really help people to decide sooner rather than later that a treatment merits further investigation or ... merits being given to kids with autism or it doesn't," she says.
Anecdotes Fired Internet, Media Buzz
Lightdale traces interest in secretin and autism to 1997-1998. That's when a report appeared in a "small medical journal," she says.
The report described the cases of three autistic children who had improved to some degree, says Lightdale.
The kids had been screened by a gastroenterologist to check for pancreatic problems, she says. The researcher didn't set out to test secretin; he wrote about the parents' anecdotal reports.
One of the parents started posting Internet reports; national TV newsmagazine coverage followed, says Lightdale.
"It was the kind of thing that gives you chills," says Lightdale. "[Parents on the show] were saying, 'Well, my child was like this one minute and got this test and within a week was completely different.'"
Science Caught off Guard
"Clinical researchers like myself were way behind," says Lightdale.
"We started to get many phone calls from people saying, 'Can my child have a secretin test?' It came out of nowhere for many of us because I wasn't in the world of autism research."
Lightdale no longer researches secretin and autism. She doesn't dismiss anecdotal reports.
"Anecdotal reports are often where great serendipitous findings are made," says Lightdale.
"I think [such reports] are appropriate, but science needs a chance to really investigate," she says.
"You need to [let peers review results]. You need lots of people to think about it, certainly before you go on some mass level of disseminating a treatment to many children with autism," says Lightdale.
Williams and colleagues reached a similar conclusion.
Future tests of secretin's effectiveness as an autism treatment "can only be justified if methodological problems of existing research can be overcome," they write.