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The Relationship Between Child Externalizing Behaviors and Parental Stress in Children with Fragile X Syndrome

Erica Mazur & Marjorie Grefer

Faculty Mentor
Jane Roberts, PhD



Fragile X syndrome (FXS) is the leading heritable cause for intellectual disabilities and the leading known genetic cause for developmental disorders such as autism spectrum disorders (ASD). The present study examined the relationship between levels of externalizing behaviors in children with FXS and increased parenting stress in parents of children with FXS. Aggressive behaviors and autism severity were examined in 48 male children diagnosed with FXS (range 2-5 years). Parenting stress was examined in 27 of their mothers and 21 of their fathers. Increased severity of autistic behavior was associated with elevated parental stress. Greater levels of parental stress were also associated with increased presentation of aggressive behaviors. These findings are important for the families of children with a FXS diagnosis because externalizing behaviors and parenting stress are likely to negatively impact family relationships.



Prevalence of fragile X syndrome (FXS) is estimated at 1 in 3,600-4,000 in males and 1 in 4,000-6,000 in females (“Fragile X-associated Disorders”). FXS is a single gene disorder known as the most common cause for intellectual disabilities and as the leading genetic cause of autism spectrum disorders (ASD). While FXS is a distinct disorder from ASD, individuals with FXS are likely to exhibit components of the ASD behavioral phenotype (Bailey, Hatton, Mesibov, Ament, & Skinner, 2000). Males with FXS may exhibit autistic behaviors such as atypical attention and hand flapping (Garber, Visootsak, & Warren, 2008). It is estimated that 46% of males with FXS receive a diagnosis of ASD (Garber et al., 2008). Other disorders such as anxiety, mood disorders, and emotional/ behavioral disturbances also have high rates of comorbidity with FXS (Hessl, Dyer-Friedman, Glaser, Wisbeck, Barajas, Taylor, & Reiss, 2001). Individuals with FXS who also are diagnosed with ASD display social communication impairments and a set of restricted and repetitive behaviors which could be associated with the presence of externalizing behaviors (e.g., aggression, refusal to comply) that reflect attempts to express emotions or manage demands placed upon them (Richman, Stevenson, & Graham, 1982). These externalizing behaviors in children with FXS may be exacerbated by parental psychopathology which could be independent or associated with child problem behavior (Hessl et al., 2001). Parents who are raising children with developmental disorders such as FXS face higher stress levels than parents raising a typically developing child (Wolf, Noh, Fisman, & Speechley, 1989). Parents who struggle to cope with the unique demands of their children are likely to have trouble interacting with their children (Hessl et al., 2001).

While children with FXS typically have a moderate intellectual disability, it is the presence of challenging behaviors that is the primary source of stress and challenge for parents and other caregivers. Some of the most common challenging behaviors reported in children with FXS include aggression and autistic behaviors (Bailey, Raspa, Olmsted, & Holiday, 2008). Examples of autistic behaviors associated with FXS are hand flapping, poor eye contact and tactile defensiveness (Tranfaglia, 2011). It is highly important to investigate problematic behaviors and their possible indicators because behavioral problems in individuals with FXS can indicate the influence of negative environmental factors (Bailey et al., 2008). For example, poor relational functioning within the family as a whole increases the likelihood that the individual with FXS will communicate by means of externalizing behaviors (Hessl et al., 2001). Children who exhibit maladaptive behaviors, such as aggressive behaviors, in early childhood are at risk for developing comorbid emotional or behavioral disorders and at risk for academic failure (Nelson, Stage, Duppong-Hurley, Synhorst & Epstein, 2007). Children who exhibit problem behaviors are likely to face more serious consequences in adolescence such as a diagnosis of an emotional/behavioral disorder or dropping out of school (Nelson et al., 2007). The consequences of externalizing behavior greatly affect individuals with FXS, who already face an array of challenges by nature of their diagnosis (Bailey, Sideris, Roberts, & Hatton, 2008).

It is estimated that 38% of males with FXS exhibit aggressive behaviors (Garber et al., 2008). These aggressive behaviors may be related to delays in language skills and frustration, consequences due to the inability to communicate (Tranfaglia, 2011). Children may also learn aggressive behaviors by seeing them modeled by others in their environments such as peers or family members (Kazdin & Whitley, 2003). Individuals with FXS may exhibit aggressive behaviors aligned with their autistic behaviors in that they may be reacting to heightened sensory input or to persons making unrealistic demands on them, which makes them frustrated and potentially aggressive.

Studies have shown that children’s externalizing behavior, including aggression, has a strong correlation with parenting stress (Bailey et al., 2008; Baker, McIntyre, Blacher, Crnic, Edelbrock & Low, 2003; Hessl et al., 2001). Parenting stress refers to how parents cope with the demands of raising a child. Raising a child with a developmental disorder includes the time constraints of specialized care, the worry that their child is not reaching their developmental milestones, and the fear that their child will never be fully independent (Wolf et al., 1989). Parents of children with a developmental disability are found to be especially vulnerable to parenting stress in relation to their children’s aggressive behaviors (Baker et al., 2003). How parental stress relates to child problem behaviors has been a complex relationship investigators have been invested in understanding.

The present study was conducted to examine how fragile X syndrome and aggressive behaviors in male children relate to parenting stress. The current study hypothesized that the higher the autism rating scores, the higher the scores of parenting stress would be. It was also hypothesized that the higher the level of aggressive behaviors, the higher the scores of parenting stress would be. 




Data were drawn from an extant dataset representing multiple studies conducted at the University of North Carolina at Chapel Hill.  Participants were recruited to partake in longitudinal studies concerning the development of FXS. The aim of the research project was concerned with investigating the cognitive, behavioral, and psychological trajectories of children with FXS. Information was obtained from young boys with FXS (N=48) and from either their mother (N=27) or father (N=21). The boys’ ages ranged from 2 to 5 years (M=59.46, SD=10.58).


Child Aggression. The Childhood Behavioral Checklist (CBCL; Achenbach, 1991) is an assessment scale completed by parents to measure the externalizing and internalizing symptoms of their children. The CBCL has a high test-retest reliability (r=0.95), indicating that this measure is stable over time. The CBCL is comprised of 195 items and eight syndrome scales, including a sub-scale for aggressive behaviors. The child aggression rating score from this sub-scale was used in the present study. Higher scores on this sub-scale indicated more aggressive behaviors.

Autistic Behavior. The Childhood Autism Rating Scale (CARS; Schopler, Reichler, & Rocher-Renner, 1988) was used to measure behaviors associated with ASD. The CARS has a high test-retest reliability (r=0.88). It also has a criterion validity of r=0.84. This indicates that the CARS is stable over time and accurately measures autistic characteristics. The CARS is a 15-item rating scale and is completed by the examiners. The total score of the CARS was used to assess autism severity with higher scores indicating more behaviors associated with ASD.

Parental Stress. The Parental Stress Inventory (PSI; Abidin, 1983) is a 120-item self-report rating scale and was completed by mothers and fathers in the study to assess levels of parental stress. The PSI has a high test-retest reliability for each subscale: the Child Domain subscale (r=0.63), the Parent Domain subscale (r=0.91), and the Total Stress subscale (r=0.96). This indicates that this measure is consistent over time. The Total Stress Variable of the PSI is the total score of stress indicators. Higher Total Stress Variables indicate more stressful experiences.


Data Collection. Participants came in to the laboratory at the University of North Carolina at Chapel Hill for their assessments. Parents filled out the CBCL regarding their child’s behavior and PSI forms regarding their own levels of stress. The research team completed the CARS with each child. Research team members scored items according to the specifications established by the respective publishers of the standardized measures.

Data Analysis. A multiple regression analysis was used to analyze the data. The CARS total score and CBCL aggressive behaviors subscale were used to determine whether participants’ severity of autistic behaviors and levels of aggressive behaviors predicted parenting stress from the PSI Total Stress Variable.



Analyses were conducted examining the scores of the Total Stress Variable from the PSI using the predictors of child aggression on the CBCL and the total score on the CARS. Several CARS total scores were above 30, indicating that those participants met the criteria for ASD (M=28.3, SD=5.7).  Other participants displayed autistic behaviors but did not meet the criteria for an ASD diagnosis because their CARS total scores were not above 30. A multiple regression analysis was conducted to examine the relationship between scores of the CARS and scores of the Total Stress Variable on the PSI. Higher scores of autistic behavior on the CARS predicted higher scores of the Total Stress Variable from the PSI (β=.31, p=.04).  Scores from the child aggression sub-scale on the CBCL did not significantly predict stress in parents (β=.27 p=.07) in this sample; however these results suggest that a relationship may be emerging.


Table 1. CARS Total Scores & CBCL Child Aggression Subscale Scores Predicting Total Stress in Parents.


Variable β Sig.
Autistic Behavior (CARS) .31 .04*
Child Aggression (CBCL) .27 .07



The current study found that increased severity of autistic behavior in children with FXS was associated with elevated parental stress. Further, the results suggest a trend level association of increased presentation of aggressive behaviors in children with FXS and greater levels of parental stress. In the present study, several CARS total scores were above 30, indicating that those participants met the criteria for ASD (M=28.3, SD=5.7).  Other participants displayed autistic behaviors but did not meet the criteria for an ASD diagnosis because their CARS total scores were not above 30. Given that individuals with ASD have problems with pragmatic and social communication as well as problems with coping, these problems may make them more vulnerable to negative parental responsiveness. If the parents of children with autism have elevated levels of stress, the children with ASD may exhibit an exacerbated level of aggression in an attempt to communicate or respond to their stressed parent. Beneficial relationships between parents and children are likely to be compromised by this type of interaction. If individuals with FXS grow up with challenges in communication and the presence of aggressive behavior, they will likely suffer in a range of settings such as schools and workplaces.

A potential limitation of this study is that we did not have a control group composed of children who are typically developing. A control group of typically developing peers would have allowed for a comparison of trends amongst groups and may have made the results of the study more generalizable to various populations.

An interesting topic for further study would be to examine how parent levels of education or parenting style relate to child problem behavior and parental stress. Parents with a higher level of education may be more disappointed by their child’s academic failures than parents with a lower level of education. Future studies could also examine how siblings or other caregivers of children with FXS experience stress in relation to the child’s level of autistic and aggressive behavior.

Parents of children with FXS are often susceptible to higher levels of parenting stress. This study suggested that higher levels of parenting stress are related to higher levels of autistic symptoms and aggressive behaviors. Stressed parents are more likely to react with maladaptive responses to their children, which can have a range of consequences for the child and the larger family system.




About the Authors


Erica MazurErica Mazur

In May 2014, I graduated Magna Cum Laude from the University of South Carolina with a B.A. in Experimental Psychology and a Leadership Distinction in Research. In fall 2014, I began my graduate studies in the School Psychology doctoral program at Louisiana State University. The present paper is based upon my Discovery Day presentation from April 2013. In this project, I analyzed an extant dataset comprised from studies conducted at UNC Chapel Hill. I executed a literature review in order to familiarize myself with previous academic works on the behavioral phenotype of fragile X syndrome, the comorbidity of autism spectrum disorder with fragile X syndrome, and parental stress. Then I ran statistical analyses and wrote the paper. Dr. Jane E. Roberts and Marjorie L. Grefer helped me revise the paper throughout the academic year. During my undergraduate career, I had the opportunity to conduct several presentations and projects. In April 2013, I received a $5,000 Magellan Scholar grant with another undergraduate student in order to examine atypical visual attention and language delays in children at risk for autism. Our Magellan proposal was inspired by our previous work in the Neurodevelopmental Disorders Lab. We presented our findings at Discovery Day in April 2014. I also conducted a research project examining attention engagement and disengagement in infants at high-risk for autism. Findings were presented in November 2013 at Louisiana State University's Undergraduate Research Conference, where I earned 1st place and a $300 prize in the Social Sciences category for my poster presentation. The Caravel submission process has been an instrumental experience in my career. Learning how to write and revise an academic paper is a skill I will need to build upon during my graduate training. After I complete my graduate studies, I hope to work as a clinician diagnosing and treating children with autism spectrum disorders.


Marjorie Grefer



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