ADHD Symptomatology in Preschoolers with Fragile X Contrasted to Idiopathic Autism

Thursday, May 11, 2017: 5:30 PM-7:00 PM
Golden Gate Ballroom (Marriott Marquis Hotel)
S. L. O'Connor1, A. L. Hogan1, K. E. Caravella2, S. M. Matherly2 and J. Roberts1, (1)Department of Psychology, University of South Carolina, Columbia, SC, (2)University of South Carolina, Columbia, SC

Attention Deficit/Hyperactivity Disorder (ADHD) is the most commonly diagnosed behavioral disorder in children, with about 11% of the general population diagnosed with ADHD. Symptoms of ADHD, such as inattention, hyperactivity and impulsivity, are present at elevated rates in children with fragile X syndrome (FXS) and autism spectrum disorder (ASD). Estimates of ADHD in school-age children fall around 60% for youth with FXS and up to 53% in ASD. Screening for comorbid disorders in these high risk groups is important to aid in diagnostic determination along with accessing and directing treatment. To our knowledge, no study has examined ADHD symptom presence or severity in preschoolers with FXS or compared the severity of ADHD symptomatology between children with ASD and FXS despite the high prevalence and significant impact ADHD has on these populations.


In the present study we characterize ADHD symptom severity across three groups of preschool-aged children: FXS, ASD and typically developing (TD) controls. This study also investigates the effect of ASD severity on the impact of ADHD symptoms in the FXS group. The effect of sex was also investigated across all three groups.


Participants included 22 children with FXS, 18 children with ASD and 18 TD children between the ages of 3-6 years old (boys’ n = 46, girls’ n = 12; Age M = 53.23, SD = 11.11). The Child Behavior Checklist 1½-5 ADHD-DSM subscale raw and t-scores (CBCL) were used to assess the presence and severity of ADHD symptoms. Cognitive functioning was measured by the Early learning composite (ELC) on the Mullen Scales of Early Learning (MSEL). Autism symptom severity was measured by the Autism Diagnostic Observation Schedule (ADOS-2).


Two ANCOVA’s were run. Both sex and Mullen ELC were co-varied in the analyses. Results show no differences in mean scores across the three groups for both the ADHD DSM scale raw and T-scores on the CBCL (p > .05). No effect of sex was found. To investigate the effect of autism symptomology on CBCL ADHD DSM subscale scores, Pearson’s correlations were calculated to look at the effect of autism severity on ADHD raw and t-scores for the FXS group. No significant relationship was found between autism severity and ADHD symptoms in the FXS group (p > .05).


The present study findings suggest that group differences on ADHD symptomology are not evident at the preschool age for these clinical samples. This finding is striking as rates of ADHD in school age samples are much higher in both FXS and ASD compared to TD peers. These findings are important and indicate that early indicators of ADHD may be muted during the preschool years or that severity of ADHD symptoms may increase dramatically across early childhood. Thus, diagnostic surveillance for ADHD is important in ASD and FXS to detect symptom severity and impairment that may emerge at older ages than community samples. This work also suggests that treatment may be initiated in the absence of overt symptoms to minimize the severity of later-emerging symptomology.