The latest in a series of studies on secretin has failed to show that giving the digestive hormone to children with autism alleviates symptoms of the disorder, according to a study funded by the National Institute of Child Health and Human Development.
The study, which appeared in the November 2001 issue of the Journal of the American Academy of Child and Adolescent Psychiatry, found that patients with autism who received a form of the hormone derived from swine showed no statistically significant improvements in the core symptoms of the disorder when compared to when the same patients received a placebo. (The core symptoms of autism involve social and communications skills.) In certain secondary measures of autism, patients receiving secretin also showed no improvement when compared to when they received a placebo.
The researchers used porcine secretin, a form of the hormone derived from pigs, and the form most commonly used in diagnostic tests of the digestive system. Previous studies have also tested laboratory manufactured secretin as a treatment for autism. The current study tested porcine secretin to rule out the possibility that the naturally occurring form of the hormone might have a different effect than does the synthetic version.
"These results, in addition to those from other secretin clinical trials, do not provide evidence to support using the hormone to treat the symptoms of autism," said Duane Alexander, M.D., director of the National Institute of Child Health and Human Development (NICHD), one of the sponsors of the study.
Interest in secretin as a possible treatment for autism, a neurodevelopmental disorder characterized by social and communication problems and repetitive behaviors and interests, arose from reports of children with autism whose symptoms improved after receiving a single dose of the hormone. Secretin is routinely given during tests to diagnose intestinal ailments, but its safety and effectiveness in treating autism were not known. Since 1999, more than a half dozen studies examined whether or not secretin could reduce symptoms in children with autism, with little evidence of benefit. Varying the doses of the hormone and giving it on more than one occasion have not proved useful in treating the disorder.
Studies Needed on Autism Treatments
"Our study reiterates the need to perform careful studies of any new treatment — even one that appears promising — before routinely prescribing it to patients," said the study's first author, Thomas Owley, M.D., Assistant Professor of Child and Adolescent Psychiatry at the University of Chicago.
The study, conducted at sites in Illinois, California, and Utah, included 56 children with autism, ranging from age three to age 12. The children met the autistic disorder criteria for two scales used to measure the "core" symptoms of autism, the Autism Diagnostic Interview-Revised (ADI-R) and the Autism Diagnostic Observation Schedule (ADOS). The core symptoms of autism pertain to social and communication skills. The researchers confirmed the diagnosis using the DSM-IV criteria, currently the standard for diagnosing autism from the American Psychiatric Association. Children who did not meet the requirements of all three scales did not participate in the study.
Children were randomized to receive either an intravenous dose of secretin, followed by a dose of harmless saline (salt) solution four weeks later, or an intravenous dose of saline, followed by a dose of secretin four weeks later.
The children went through detailed evaluations before receiving treatment, and then every two weeks, to see if their symptoms of autism showed any change. These evaluations continued until eight weeks after treatment, to ensure that the researchers would detect any positive effect.