Selective serotonin reuptake inhibitors for autism spectrum disorders

Autism affects approximately 1 person in every 150. People with autism have problems with social interaction and communication and can become preoccupied with objects and routines or rituals in a way that interferes with their day to day life. Many individuals with autism have intellectual impairment, but among these people some have islets of normal or even above normal ability. Autism causes problems for the individuals and for their families and carers; and intensive services such as special education, multidisciplinary health care and community support services are often needed. Because autism is such a profound problem, parents and carers can be drawn to a wide variety of therapies. That said, the mainstay of treatment in early life is behavioural, educational and specific (such as speech) therapies. Drug treatment has a smaller, but nevertheless important, role and our Cochrane review examines the evidence for one class of these, the selective serotonin reuptake inhibitors or SSRIs (1). In recent years, prescribing of serotonin enhancing drugs has increased more than any other medication class for autism, with the rationale being that serotonin is thought to mediate some of the brain processes that are likely to occur in autism. However, the SSRIs have gained a negative reputation among children and adolescents, because they have been associated with an increased risk for suiciderelated behaviours. Amidst these doubts about the safety of the drugs, our review was needed to find out whether there is sufficient evidence on their potential benefits and harms to be able to recommend the use of serotonin enhancing drugs in autism. We found that there were few trials, most of which were small, of uncertain quality and had used a wide variety measure to measure a wide range of outcomes. From the studies available, we couldn’t find any evidence of a positive effect for children, and the results for adults were equivocal. Only one study in adults assessed depression and anxiety outcomes, and one other study assessed improvements in aggression. All the trials were short term, typically giving the drugs for a matter of weeks, even though we know that long term therapy over months and years would be required if serotonin enhancing drugs did reduce the problems created by autism. Regarding safety, a child taking citalopram in one of the trials experienced a prolonged seizure but we found no information suggesting an increase in suicide-related behaviours. After doing the review, it is clear that gaps remain in the evidence base. These gaps would be resolved by the conduct of one or two large studies with a low risk of bias to investigate the serotonin drugs that have already been studied in small trials, as well as the serotonin enhancing drugs that have yet to feature in autism research. At the moment, though, and on the basis of the available data, we cannot advise the universal use of serotonin enhancing drugs for children who have autism and no other conditions. Where someone with autism does have other problems, such as obsessive compulsive disorder, depression, or anxiety, for which serotonin enhancing drugs might also be used, decisions about the use of the drugs should be made on an individual basis.