Behavior Characteristics in Children With Fragile X Syndrome

Children with fragile X syndrome often have many positive behavioral characteristics. They are described as sweet and loving, with a strong desire for social interactions. Children with fragile X often have good senses of humor and enjoy jokes and humorous situations.

Children with fragile X also often have a variety of behavioral challenges. Behavioral challenges are one of the main areas listed on checklists for the identification of persons with fragile X syndrome.

A high number of boys with fragile X (80-90%) are described as distractible and impulsive, with symptoms of attention deficit hyperactivity disorder (ADHD) or attention deficit disorder (ADD). They may have short attention spans and difficulty staying on task. Girls may show less hyperactivity, but still have many symptoms of ADD.

Many boys have unusual, stereotypic behaviors, such as hand flapping and chewing on skin, clothing, or objects, which may be connected to sensory processing problems and anxiety. Sensory processing problems may manifest themselves as tactile defensiveness, such as oral motor defensiveness, sensitivity to sound or light, and poor eye contact. About 90% of boys with fragile X syndrome are reported to have some type of sensory defensiveness.

Anxiety in both boys and girls manifests itself in various ways. Some persons with fragile X become very worried about changes in routine or upcoming stressful events (e.g., fire drills, assemblies). This is often referred to as "hypervigilance". Parents often report that their children stiffen up when angry or upset, becoming rigid and very tense. Sometimes, they simply tighten up their hands. Tantrums may be a result of anxiety and a feeling of being overwhelmed. Crowds and new situations may cause boys to whine, cry, or misbehave, in attempts to get out of the overwhelming settings.

Many of the behavior problems of both boys and girls with fragile X syndrome overlap with the pragmatic (conversational) difficulties they have in language. The poor eye contact and difficulty sustaining a conversation cause many social weaknesses. Perseverative speech and self-talk may be symptoms of anxiety.