Association Between Executive Functioning and Attention Deficit/Hyperactivity Disorder Symptoms in Younger Siblings of Children with Autism Spectrum Disorder.

Background:

Relatives of individuals with autism spectrum disorder (ASD) often present with a variety of social and neurocognitive difficulties, despite not meeting formal criteria for ASD. This profile is termed “broader autism phenotype” (BAP) and often includes subclinical ASD symptoms. Difficulties in executive functioning (EF) characterize ASD and are associated with BAP. However, EF deficits are not unique to ASD, as it is also central to other disorders, including Attention Deficit/Hyperactivity Disorder (ADHD). ADHD and broader attentional problems are also present in relatives of individuals with ASD; therefore, whether EF difficulties in this population are more associated with ASD- or ADHD-like clinical profiles remains unclear.

Objectives:

To evaluate whether EF vulnerabilities are associated with symptoms of either BAP (sub-threshold ASD) or attention problems in a sample of younger siblings of children with ASD.

Methods:

22 younger siblings of children with ASD (Mean age: 65.55 months; SD: 5.98, Range: 60-80 months) were administered a battery of EF tests from the NEPSY-II (Inhibition-Naming, Inhibition-Inhibition, Design Fluency, Auditory Attention, Statue) and evaluated for ASD and ADHD using the Social Responsiveness Scale (SRS), Autism Diagnostic Observation Schedule (ADOS), Child Behavior Checklist (CBCL) Attention Problems subscale, and clinician best estimate (CBE) of ASD and ADHD. Bivariate correlations were conducted to assess the association between EF and clinical symptomatology.

Results:

The EF Composite was not correlated significantly to indices of ASD-related symptomatology on the ADOS (r=-.074, p=.74), SRS (r=-.233, p=.32), or ASD CBE (r=.187, p=.42). Moreover, no EF subtest correlated significantly with any measure of ASD-related symptomatology (all ps>0.17). In contrast, EF abilities at five years-old were correlated significantly with the CBE of ADHD (r=-.663, p=.001) and correlations between the EF composite and parent reported symptoms on the CBCL Attention Problems subscale score approached statistical significance (r=-.398, p=.067). The Auditory Attention subtest scaled score correlated significantly with the CBCL Attention Problems score (r=-.515, p=.014), as well as marginally with the ADHD CBE score (r=-.350, p=.12). ADHD CBE correlated significantly with Inhibition-Naming (r=-.581, p=.006), Inhibition–Inhibition (r=-.550, p=.01), Statue (r=-.480, p=.028), and Design Fluency (r=-.468, p=.032).

Conclusions:

In younger siblings of children with ASD who do not meet criteria for ASD, EF difficulties are more associated with broad attention problems and ADHD than with subthreshold ASD features typically associated with BAP. Despite the high recurrence rate of ASD in siblings, these findings suggest that, when considering EF difficulties in relatives of individuals with ASD, clinicians should consider other clinical profiles, such as ADHD. In addition, further exploring the overlap and boundaries between ASD and ADHD may be an important area for future studies when considering EF in both clinical and non-clinical populations.