The study, which appears in the December 9 New England Journal of Medicine, was led by James W. Bodfish, Ph.D., of the Western Carolina Center and the University of North Carolina at Chapel Hill, and Dr. Adrian D. Sandler, M.D., of the Center for Child Development at Thoms Rehabilitation Hospital, in Asheville, North Carolina.
"These are the first public results of an intensive NICHD effort to investigate the use of secretin in the treatment of autism," said Duane Alexander, M.D., director of the NICHD. "These findings strongly suggest that secretin should not be recommended to treat autism until the results of our other ongoing studies are known."
Secretin is a hormone produced by a part of the intestine called the duodenum. The hormone acts upon the pancreas to assist in digestion. Beginning last year, various media accounts described how a three-year-old boy with autism and symptoms of digestive disorders improved dramatically within a week of administration of secretin during a medical procedure. Despite the apparent promise of the hormone, however, little scientific evidence exists to show whether secretin is a safe and effective treatment for autism.
As a result of the publicity about the boy's experience, prices for secretin skyrocketed. According to a few accounts, some of the sales were fraudulent, with laboratory tests showing that some parents had purchased preparations containing no secretin at all. No precise statistics exist, but many experts believe thousands of children have received the hormone. Anecdotal reports of the hormone's success vary. Some parents reported that their children improved dramatically, other parents saw no effect at all, and a few others report that their children's symptoms worsened. Because of these reports, the NICHD quickly funded a number of clinical studies to determine the possible use of secretin as a treatment for autism.
In all, 56 children with autistic disorders took part in the study. Of these, 28 received a single intravenous dose of synthetic human secretin. The remaining children were injected with a harmless salt (saline) solution. The researchers administered a battery of behavioral tests to the children at intervals of one day, one week, and four weeks after the treatment.
For each of the 16 measures of the children's behavior, the secretin treatment did not result in any more statistically significant improvements in behavior than did treatment with the placebo. Improvements were seen on six of the behavioral measures, but again, these improvements did not differ significantly from the placebo group.
Drs. Bodfish and Sandler noted, however, that the study had several limitations. Because the study was only four weeks' duration, it could not detect any improvements that might have occurred over a longer period of time. Also, study participants received only one injection of secretin, and it is possible that more than one injection would be required before any effects were noticeable.
Moreover, the authors wrote, recent studies of autism symptoms suggest that there may be various subtypes of autism. For this reason, it is theoretically possible that individuals who were not able to take part in the study might benefit from secretin. Finally, the investigators studied synthetic secretin. Most of the news accounts of secretin have involved biological secretin-secretin extracted from the duodenum of pigs rather than artificially manufactured. The authors noted that it is also possible, although unlikely, that the two forms of the hormone differ in their effects. Despite these limitations, however, the researchers believe their results provide clear guidance for clinical practice.
"We have been unable to show any benefit from the secretin treatment," Dr. Sandler said. "This suggests that secretin should be avoided as a treatment for autism until more information is available."
The study authors said that the attention surrounding media reports of secretin may have been responsible for the seeming improvements in the placebo group.
"It's our hypothesis that the optimism of the early reports may have biased clinicians and caregivers toward seeing improvements, when no improvements were made," Dr. Bodfish said.
The NICHD special assistant for autism programs, Marie Bristol-Power, Ph.D., noted that, despite secretin's early promise, there are potential concerns with its use to treat autism. Because biological secretin is derived from pigs, there is a possibility that its repeated use might result in an allergic response.
"Secretin may be promising, but it may also be hazardous," Dr. Bristol-Power said. "Its use at this time is probably best supervised in a carefully controlled clinical trial."
For this reason, Dr. Bristol-Power added, other studies are now seeking to determine whether secretin might be effective when given at varying doses and on more than one occasion, whether it benefits children with a particular group of symptoms, and whether biological secretin is more effective than the synthetic version.
The NICHD is one of the Institutes comprising the National Institutes of Health (NIH), the Federal government's premier biomedical research agency. NICHD supports and conducts research on the reproductive, neurobiological, developmental, and behavioral processes that determine and maintain the health of children, adults, families, and populations. The NICHD website, http://www.nichd.nih.gov, contains information about the Institute and its mission.
Autism research is supported by several other NIH Institutes in addition to the NICHD, including: The National Institute on Deafness and Other Communication Disorders, The National Institute of Mental Health, and The National Institute of Neurological Disorders and Stroke.