Association of Deficits In Executive Functioning and Neurocognitive Status In Low/High Levels of Autistic Traits In a Sub-Clinical Sample

Background: Previous work demonstrated the Executive Function Index (EFI) useful in detecting neurocognitive differences between sub-clinical groups reporting higher and lower levels of autistic traits as measured by the Autism Spectrum Quotient (AQ). As levels of autistic traits increased (AQ), executive functioning decreased (EFI Total). High-AQ individuals reported higher deficits than low-AQ individuals in Motivational Drive, Empathy and Organization. Assessing additional domains, such as those measured by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS; Randolph, 1998), may provide convergent evidence for executive deficits related to autistic-trait severity in addition to identifying other neurocognitive aspects unique to Autism Spectrum Disorders (ASD).

Objectives: Study expands on demonstrated AQ and EFI relationships and evaluates possible RBANS associations. Negative correlations between AQ and EFI measures with EFI means for Low-AQ group expected higher than High-AQ. Lower performance on RBANS Language Index was predicted to coincide with higher AQ, based on language deficits salient to ASD. RBANS Attention Index was expected to moderately correlate with general executive functioning. Attention differences were not expected between High-AQ and Low-AQ groups, as inattention is not a core ASDimpairment. Possible predictors of AQ trait levels using EFI and RBANS indicators were explored.

Methods:  Self-rated autism trait level and executive function performance were measured using the AQ and EFI. The AQ (50 questions) quantifies autistic traits on the autism-normality continuum with sub-clinical High-AQ and Low-AQ groups following the high (16-31) and low (5-15) AQ score dichotomy. The EFI (27 questions) assesses 5 frontal lobe functions: Motivational Drive, Impulse Control, Empathy, Organization, and Strategic Planning. The RBANS battery of 10 standardized subtests measures Immediate and Delayed Memory, Visuospatial Skills, Language and Attention. Sample consisted of Midwestern university students (N=214, ages 18-50, M=21.47). 

Results:  Negative correlations were found between AQ and Motivational Drive, Organization, and EFI Total along with mean group differences between Low-AQ and High-AQ groups. Negative correlations were found between AQ and RBANS Picture Naming, Semantic Fluency, Story Recall, and Language Index. RBANS Attention Index positively correlated with EFI Total. High-AQ group means were lower than Low-ASQ on RBANS Picture Naming, Story Recall, and Language Index. Attention Index group scores did not significantly differ. Exploratory linear regression analysis using a sample subset (N=100, ages 18 - 41, M=21.68) matched by group propensity revealed predictors of Motivational Drive (β = -.32, p = .001), Organization (β = -.23, p = .01) and Picture Naming (β = -.30, p = .001) accounting for 27% of AQ variance, F(3,94) = 11.63, p <.001.

Conclusions:  Negative correlations between AQ and EFI persist as results suggest that some aspects of executive functioning show decrement with increases in autistic trait levels.  AQ and RBANS associations refine the ASD neurocognitive profile to include intact attention and impairments found in confrontational naming, semantic fluency and recall of contextual information. Results also suggest that deficits in motivational drive may moderate neurocognitive performance - an important consideration when interpreting neuropsychological performance within the autism continuum.