Autism has recently hit the radar screen in psychiatry and pediatrics. This is partly due to an increase in prevalence that has been widely reported in the media, coupled with ongoing debate regarding whether vaccines are causing this so-called "autism epidemic.” In addition, risperidone was recently the first medication approved for use in autism, contributing further to the buzz surrounding the condition.
We’ll cover all these issues in this brief article, but first, what is autism? In DSM-IV, autism is one of five conditions under the umbrella term “pervasive developmental disorder”: autistic disorder, Asperger’s disorder, Rett’s disorder, childhood disintegrative disorder, and PDD not otherwise specified. In this article we’ll focus on autism and Asperger’s, two of the prominent examples of the “autistic spectrum disorders” (ASD). Autism is defined by a characteristic triad of symptoms: 1. Social interaction problems (e.g., poor eye contact, aloofness); 2. Impaired communication (e.g., delayed speech development, odd speech patterns, echolalia, inability to sustain a normal conversation); rigid or repetitive patterns of behaviors and interests (rocking, hand flapping, lining toys up, preoccupation with one particular interest). The criteria sound abstract until you actually see patients exhibiting them. For those with little experience in this field, the internet abounds with video clips of autistic patients. For example, if you type “autism” or “Asperger’s syndrome” into the search bar of youtube.com, you can get a very quick education in how to spot typical autistic symptoms.
The cause of ASDs is unknown, although 30% of children with autism have an identifiable organic cause, such as Fragile X syndrome and inborn metabolic disorders. One third of autistic patients eventually develop a seizure disorder, and over half have mental retardation though formally testing these patients’ intellectual function is difficult because of their communication impairments. A recent spate of exciting research is uncovering the genetic abnormalities underlying some patients with autism, and the standard medical workup now includes Fragile X and high resolution chromosome testing (for a non-academic but fascinating explanation of this research, see Wallis, Time Magazine, “The Fragile X” Factor, July 7, 2008).
The prevalence of autism has steadily increased since the late 1980s, from an older figure of about 0.1% to current figures in the range of about 0.3-0.5% of children, with a male to female ratio of from 2:1 to 6:1, depending on the study (Johnson CP, et al., Pediatrics 2007;120:1183-1215). Is autism catching? Not according to most researchers, who believe that the increased prevalence is due to increased awareness of childhood neuropsychiatric diseases, a progressive broadening of the DSM diagnostic criteria, and the fact that autism was declared a disability category by the federal government in 1991, providing a very real financial incentive for parents to seek an autism diagnosis for their affected children. Nonetheless, this issue remains controversial, with some researchers believing that a portion of the increased prevalence may be due to as yet unknown environmental factors.
Is autism caused by vaccines? Almost certainly not, because the timing of vaccine introduction and autism do not support such an association. In a Minnesota study, for example, the MMR vaccine was introduced in 1971, but the increase in autism cases did not begin until after 1990. Conversely, in a study from Denmark, vaccines containing thimerosal (a mercury-containing preservative) were removed from the market in 1992, but the increase in autism rates continued through 2000 (referenced in Barbaresi WJ et al., Arch Pediatr Adolesc Med, 2005; 159: 37 - 44.) Nonetheless, thimerosal was removed from most U.S. vaccines in 2001.
There is no cure for autism. Treatment is usually educational and behavioral, with a treatment known as Applied Behavior Analysis (ABA) considered to be particularly effective in helping patients integrate into society. Patients should also generally receive speech and language therapy, occupational therapy, and social skills training as part of their educational package. There are various popular but unproven approaches, such as “sensory integration therapy” (sometimes part of occupational therapy), facilitated communication, auditory integration training, or music therapy.
The only medication that is FDA approved for autism is risperidone, indicated specifically for the irritability associated with the condition. Children with autism can have severe tantrums and outbursts that can lead to self injury. In two pivotal eight week double blind trials, risperidone was more effective than placebo in decreasing irritability, in doses ranging from 0.5 to 2.5 mg/day. Somnolence and weight gain were common (see Risperdal package insert for more information about the clinical studies). Note, however, that kids with autism can exhibit agitation due to medical problems, such as constipation or ear infections, so be quick to refer to a pediatrician.
SSRIs may be helpful for the anxiety and repetitive behaviors in autistic children, but you have to dose low to prevent agitation as a side effect (Kolevzon A, et al., J Clin Psychiatry 2006;67:407-14). Otherwise, methylphenidate is sometimes used for the hyperactivity seen in autism, and was more effective than placebo in a double-blind placebo controlled crossover trial (Research Units on Pediatric Psychopharmacology (RUPP) Autism Network, Arch Gen Psychiatry 2005;62:1266-1274.) Again, dose low, for example starting with liquid methylin at 2.5 mg/day. The alpha-2 agonist guanfacine is also helpful for treatment of hyperactivity (see our update on ADHD meds in this issue).
Most adult psychiatrists will likely see more patients with Asperger’s Syndrome (AS) rather than classical autism. Sometimes considered a “high functioning” variant of autism, AS was recently reviewed in a clinically-oriented article in the American Journal of Psychiatry (Toth K and King BH, 165 (8): 958-963).
The best way to think about AS is that these patients are autistics with good verbal abilities. The DSM-IV criteria for AS are similar to autism in that they specify both social impairment and stereotyped interests, but unlike autism, impairment in language is not part of the diagnosis. Patients with AS are often more functional, depending on the severity of their symptoms. When presenting to the office, they may appear similar to someone with social anxiety disorder, in the sense of making poor eye contact and having difficulty relating easily but they are differentiated by their rigidity and their repetitive behaviors. They have a high incidence of depression, around 40%. As in autism, the treatment for AS revolves around therapy to improve socialization, and symptomatic treatment for comorbid psychiatric conditions as they arise.
Autism: No cures but both therapy and meds are helpful.