Using a change in the ADOS social-communication score as a primary measure, researchers found no statistically significant differences in the group when they received secretin versus when they received the placebo. Assessments of secondary measures showed no treatment effect at all between the secretin and placebo groups. The results were the same eight weeks after the treatment.
No Improvement in Autism Symptoms Shown
None of the five controlled clinical trials published on secretin, either in the porcine form or in the synthetic form, given at varying doses, have shown any improvement over the placebo in symptoms of autism.
Open label studies — those in which researchers know what they are giving to the patients — comparing secretin with the saline solution, have suggested that some improvements might result when secretin is used in patients with autism. The current study was "double-blinded," meaning that neither the patients nor the researchers who treated and evaluated the patients knew when the patients received the secretin or the placebo.
The purpose of studying a treatment (secretin) against a placebo (saline) in a double-blinded design is to assure objectivity in the evaluation of a person's response to a medication by eliminating any bias that might be caused by the expectations of the participants.
Scientifically, a double-blinded, placebo-controlled design is considered optimal in investigations designed to determine whether a treatment is effective. This study also used a cross-over design, in which the same patients are evaluated on placebo and treatment, rather than comparing one group receiving treatment and another receiving placebo. Because of its objective nature, the study provides strong evidence that the use of secretin does not improve autistic symptoms and behaviors. However, it is not possible to say from such a relatively small study whether or not there may be a small sub-group of autistic patients who may experience some benefit from secretin.
"This multi-site study analyzed possible changes in autistic symptoms based on very well accepted measures," said Laurence Stanford, Ph.D., a program officer in NICHD's Mental Retardation and Developmental Disabilities Branch. "The study results reinforce the findings of other controlled clinical trials on secretin that, for most people with autism, the hormone is not an effective treatment."
The study was conducted as part of the Collaborative Network on the Neurobiology and Genetics of Autism, supported by the NICHD and the National Institute on Deafness and Other Communication Disorders (NIDCD), both parts of the National Institutes of Health (NIH), the biomedical research arm of the federal government. Additional support for the trial came from the National Institute of Mental Health and the National Center for Research Resources at the NIH, and from the University of California-Davis Medical Investigation of Neurodevelopmental Disorders (MIND) Institute.
The NICHD is one of the Institutes comprising the NIH, the premier biomedical research agency in the federal government. The NICHD supports and conducts research on development before and after birth; maternal, child, and family health; reproductive biology and population issues; and medical rehabilitation. NICHD publications, as well as information about the Institute, are available from the NICHD web site, http://www.nichd.nih.gov, or from the NICHD Clearinghouse, 1-800-370-2943, e-mail NICHDClearinghouse@mail.nih.gov.