Autism Spectrum and Executive Function

Background: We examined the relationship between high functioning Autism Spectrum disorder (HFA), as measured by the Autism Spectrum Quotient (ASQ) questionnaire, and underlying neuropsychological performance, specifically frontal lobe and executive function, as measured by the Executive Function Index (EFI, Spinella, 2004).  There is some indication that deficits in executive function are a hallmark of HFA (Joseph, et al., 2005) and that HFA individuals lack certain aspects of motivation (Charman, 2005), which also relates to frontal lobe function. 

Objectives: To date, no one has used the ASQ and EFI together in a single study.  We expect greater executive function deficit (lower EFI scores) in individuals possessing a greater number of HFA traits and behaviors (higher ASQ scores), as compared to individuals as possessing fewer such traits and behaviors.  Thus, the association between ASQ scores and EFI scores should be negative. 

Methods: Fifty-five undergraduates took the Autism Spectrum Quotient (ASQ) and the Executive Function Index (EFI).  Hurst, et al. (2007) have recently showed that the AQ shows good validity, test-retest reliability, and internal consistency.  The ASQ can rapidly (it contains 50 questions, 10 each in 5 domains including social skill, attention switching, attention to detail, communication, and imagination) quantify where an individual falls on the continuum from autism to normality, with scores at or above 32 useful for distinguishing between individuals who have clinically significant levels of autistic traits and those that do not.  Subjects also took  the Executive Function Index (EFI; Spinella, 2004), a 27 item self-report scale that measures five areas associated with frontal lobe function (motivational drive, strategic planning, organization, impulse control, empathy, plus a total score).  Higher scores indicate better frontal lobe functioning.

Results: ASQ scores ranged from 5-28 (Mean = 13.85, SD = 5.11).  Across the 5 EFI domains, scores ranged from 11-30, with total score ranging from 87-126 (mean = 104.96).  Pearson correlations between ASQ and EFI scores resulted in the following: Motivational Drive (r = - .20, p = .07), Impulse Control (r = .07, p = .31), Empathy (r = -.10, p = .24), Organization (r = - .11, p = .22), Strategic Planning (r = .11, p = .21), EFI Total (r = -.06, p = .33).  

Conclusions: Many of the associations we predicted (as ASQ increases, EFI decreases) were in the right direction.   Increases in ASQ score (suggesting more HFA behaviors), resulted in decreases in EFI scores, suggesting more executive function deficit (for Motivational Drive, Empathy, Organization, and EFI Total).  Charman (2005) showed that HFA individuals show evidence of a lack of motivation regarding sharing intentions and the correlation between ASQ and

Motivational Drive

was r = - .22, p = .07.   It should be noted that none of the 55 subjects tested thus far have exceeded the cut-off score of 32, which may also have impacted results.  Regardless, the EFI is a quick, reliable, and valid indicator of various domains of executive function and may be a useful tool for those investigating frontal lobe deficit and its impact on HFA individuals.