Risperidone, a drug used to control schizophrenia symptoms, may also help treat behaviors found in autism spectrum disorder, according to a new review of studies.
The reviewers looked at three randomized, placebo-controlled studies of risperidone (Risperdal) involving 211 participants, including 31 adults.
"[We found] that risperidone may be beneficial for various aspects of autism including irritability, repetition and hyperactivity," said researchers led by Dr. Ora Jesner of the University of Bristol, in England. But the drug's benefits may be offset by its side effects, with weight gain the most prominent.
Often diagnosed within the first three years of life, autism spectrum disorder leads to difficulties with social relationships, language and communication skills. Symptoms include withdrawal from social interactions, irritability, problems communicating and repetitive behaviors.
It is known as a "spectrum" disorder because there is a wide variation in how it affects individuals. Figures from the U.S. Centers for Disease Control and Prevention show that as many as 1.5 million Americans may have some form of the disorder.
"Autism spectrum disorder affects many families worldwide," Jesner said. "At present many of the interventions available are not evidence-based." He said he and co-author Dr. Mehrnoosh Aref-Adib "wanted to analyze the evidence for one important antipsychotic [drug] used for the condition."
The review appears in the latest issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.
Because of the small number of studies, wide range of different scales used to assess outcomes and sizes of the trials themselves, the researchers were only able to look at how well the patients responded for the three specific symptoms of irritability, repetitive movement and social withdrawal.
In addition to weight gain, significant side effects included involuntary muscle movements. As the studies were of short duration, long-term side effects and usefulness remain unknown. Since risperidone does not cure the disorder and may have to be continued for a long period of time, this is an important missing piece.
Susan Levy, M.D., director of the Regional Autism Center at The Children's Hospital of Philadelphia, said that the authors' weak support for the medication in the conclusion surprised her.
"The researchers seemed to be lukewarm towards their positive findings," said Levy, who was not involved with the study. "From my personal experience, this medication can be quite helpful for behavioral difficulties."
The Cochrane reviewers and Levy stress that parents and caregivers should be careful about expecting too much from the medication when talking about this treatment with their doctors. Not all behavioral problems can be helped with risperidone and both side effects and improvements from the drug should be considered.
"As ASD is diagnosed at a young age and these short trials lack long-term data, parents or caregivers need to be aware it is not known how long the medication needs to be continued — potentially for a lifetime," the researchers said. "This is particularly important given the side effects."
Levy termed risperidone "a more serious medication" that she would reserve for more serious difficulties.
"It needs to be stressed to the parents and others that this is not a cure for autism or for the core symptoms of ASD," Levy said. "But it works well for some of the associated problems."