FXS and Autism: Similar But Different

Clinical Insights into the Similarities and Differences for Diagnosis and Treatment

While it has long been known that individuals with fragile X syndrome often exhibit autistic tendencies, only very recently has the possibility been raised that the two conditions may have considerably more overlap than previously thought. Scientists at various Fragile X centers are studying whether this overlap may extend beyond mere behavioral similarities but perhaps include genetic or biological components as well. That research may yet prove to have far-reaching effects.

Meanwhile, parents, educators and clinicians in the FX field have continued to note the similarities and differences between the two conditions so they can plan appropriate interventions based on the specific characteristics and needs of each individual. It was in that spirit that a well-attended panel discussion at the 13th International Fragile X Conference in Miami pondered the topic: “FXS and Autism: Clinical Insights into the Similarities and Differences for Diagnosis and Treatment.”

The discussion provided clinical perspectives on the behavioral differences between fragile X syndrome and what are thought to be core features of autism. There is still much to be learned about identifying behaviors that suggest the presence or absence of autism in FXS, so much of the discussion was exploratory and tentative. As the science advances, researchers and clinicians will achieve a deeper understanding of the overlap between the two conditions, and how that overlap affects both of them. Moderator Vicki Sudhalter, PhD, led a distinguished panel of clinicians that included Tracy Stackhouse, MA/OTR Sarah Scharfenaker, MACCC-SLP, Walter Kaufman, MD, and Richard Belser, PhD.

  • Fragile X syndrome causes a range of functioning across domains. It is a specific, identifiable condition with a known genetic cause. Autism is identified by a cluster of symptoms rather than a specific condition, and it has many causes, most of them unknown. There is overlap, in that some individuals with FXS may have autism, and some may not. Additionally, FXS accounts for the leading known genetic cause of autism.
  • Clinicians must understand the differences between the two conditions in order to avoid misdiagnosis and improper treatment. Likewise, clinicians must appreciate the similarities. Harnessing what is known about autism in particular, given its larger cache of treatment strategies, can help advance treatment and educational plans as appropriate.
  • Characteristics common to both autism and FXS include poor eye contact (more on that below), social deficits, ayptical language and repetitive behaviors. The core deficit in autism is social interaction. The coredeficit in FXS is intellectual function and hyperarousal/anxiety. A key point related to these differences: People with FXS tend to be deeply desirous of human interaction, but the social anxiety that also typifies the condition often causes them to act otherwise, which prevents success. People with autism are largely unaware of the function others serve in relation to themselves, hence they rarely seek social interaction.
  • Eye contact is a key element of social interaction, and though “poor” eye contact is symptomatic of both FXS and autism, the type of eye contact is substantially different. People with FXS directly avoid eye contact, looking off in another direction to cope with their social anxiety, while people with autism are unaware of why they should use eye gaze as a source of information or interaction. Insisting on eye contact with those who have FXS is most always counterproductive, leading to greatly heightened anxiety. Insisting on eye contact with those who have autism simply tends to be ineffective.
  • Even when they are staring off elsewhere, people with FXS tend to be acutely aware of their surroundings. Like a good politician or salesperson, they “read” a room effectively, accurately gauging others’ moods and anxiety levels. They long to participate, to joke and be joked with. They want to be inside a social circle-but they typically need a great deal of acceptance, invitation and training to be successful at it. In contrast, people with autism more often really do want to be left alone, and attempts to include them in social activities thus face more severe obstacles than with FXS.
  • Imitation is a pivotal developmental skill that is generally a strength for those with FXS and typically impaired in people with autism. If imitation is impaired in those with FXS, it provides useful information to help determine additional diagnosis and treatment plans.
  • Teachers and caregivers often say they don’t need to know about FXS because they have previously had children with autism in their classes or homes. But interventions appropriate for FXS may be quite opposite those of autism.
  • Both FXS and autism are typified by repetitive behaviors, but in FXS, this is most commonly seen in hand-flapping and body-stiffening. Those with FXS tend to exhibit repetitive behaviors due to excitement, anxiety, or difficulty “stopping” or inhibiting their behavior. People with autism engage in those behaviors as well, but for less specific and more varied reasons. What appears to be a need for vestibular stimulation results in much spinning and jumping; what appears to be a need for sameness results in restricted repeatable actions such as rubbing a piece of wood or twirling a string; what appears to be a need for soothing results in pacing and rocking.
  • At base, most FXS behavioral issues are traceable to the twin challenges of managing anxiety and hyperarousal. Autism, being the cluster of conditions it is, is more complex and multi-faceted in its behavioral roots and manifestations.
  • We know more of what to do for FXS today than ever before, while autism remains more challenging owing to its greater variance and the much lower level of social need exhibited in the condition.
  • The crucial point for teachers, therapists and others involved in the care of those with FXS is not to lump them in with autism as more or less a common diagnosis requiring a common set of interventions. FXS is still best treated utilizing what is known specifically about the condition.