Behavior Problems and Social Competence in Fragile X Syndrome: A Systematic Review

Abstract

Fragile X syndrome (FXS) causes intellectual disability and is the known leading cause of autism. Common problems in FXS include behavior and social problems. Along with syndromic characteristics and autism comorbidity, environmental factors might influence these difficulties. This systematic review focuses on the last 20 years of studies concerning behavior and social problems in FXS, considering environmental and personal variables that might influence both problems. Three databases were reviewed, leading to fifty-one studies meeting the inclusion criteria. Attention deficit hyperactivity disorder (ADHD) problems remain the greatest behavior problems, with behavioral problems and social competence being stable during the 20 years. Some developmental trajectories might have changed due to higher methodological control, such as aggressive behavior and attention problems. The socialization trajectory from childhood to adolescence remains unclear. Comorbidity with autism in individuals with FXS increased behavior problems and worsened social competence profiles. At the same time, comparisons between individuals with comorbid FXS and autism and individuals with autism might help define the comorbid phenotype. Environmental factors and parental characteristics influenced behavior problems and social competence. Higher methodological control is needed in studies including autism symptomatology and parental characteristics. More studies comparing autism in FXS with idiopathic autism are needed to discern differences between conditions.

Keywords: aggressive; anxiety; attention; autism; behavior problems; fragile X syndrome; social competence; socialization; withdrawn.

Figure A1

Trajectories of behavior problems over the years reported by the studies reviewed. This graph provides descriptive information of the trajectories reported in the studies reviewed [22,77,78,80,81,83,84,86,87,88]. The Y-axis has been removed because of the use of different measures and comparisons not being possible. Higher or lower lines do not represent greater problem behaviors or a higher frequency of behavior problems, nor does the slope. Each line should be compared with itself. For example, in this graph, tantrum scores compared with physical aggression are not higher, nor do they decrease faster over the years. One finding from the graph is that tantrum scores decreased from 5 to 19 years in [83].

Figure A2

Trajectories of social competence from the studies reviewed. This graph provides descriptive information of the trajectories reported in the studies reviewed [34,59,77,78,84,86,87,89,90,91,92,93,94,95,96,97]. The Y-axis has been removed because of the use of different measures and comparisons not being possible. Higher or lower lines do not represent greater problem behaviors or a higher frequency of behavior problems, nor does the slope. Each line should be compared with itself. For example, in this graph, social anxiety and social skills increase over the years, but scores for social skills are not higher than those of social anxiety, nor do social skills increase faster over the years. One finding from the graph is that social skills increased from 3 to 6 years in [34].

Figure 1

Based on PRISMA flowchart [74].