Executive Functioning in Middle Adulthood: A Follow up Study of Children Diagnosed with ASD from 1970-1999

Background: Executive functioning (EF) refers to a range of higher order cognitive skills, which are considered integral to goal-directed, flexible behavior. Impairments in EF are reported in ASD, though there is some disagreement about the pattern of impairments. While there are a growing number of adults with ASD, less research is available on EF in middle adulthood and ASD and its relations to other aspects of adult functioning.

Objectives: Objectives of this study were to: 1) examine the profile of EF strengths and weaknesses in adults with ASD; 2) compare ratings of real-world EF skills to standardized, behavioral measures of EF; 3) examine how executive functions relate to other measures of functioning (adaptive behavior, employment, quality of life) in middle adulthood for individuals with ASD diagnosed as children.

Methods: Participants were 24 adults with ASD (age range 27-57 years; M age=35) who completed behavioral assessments of EF (D-KEFS: Trail Making Test, Color-Word Interference, Verbal Fluency), self-reported EF (BRIEF-Adult Version), and IQ (Stanford Binet-5; FSIQ range 73-120; M FSIQ=91.3). Caregivers of adults with ASD completed measures assessing their adult’s EF (BRIEF-Adult Version), a measure of adaptive behavior (Vineland-II), and questions about the adult’s employment and quality of life. Analyses were conducted to examine the profile of EF in middle adulthood and the relation of EF to areas of adult functioning.

Results: 1) Across domains assessed, adults with ASD performed similarly on D-KEFS subtests (scaled score range 7.0-9.21, p’s > .05) to the expected performance for adults with similar FSIQ (z-score transformed mean = 8.27). However, they reported significantly more difficulties on self- and informant-report BRIEF-A indices (t-score range 54.25-57.21 compared z-score transformed mean). 2) Controlling for FSIQ, the only D-KEFS measure correlated with self- or informant-report on the BRIEF-A was Color-Word Interference Inhibition (both r’s > -.51, p’s < .02), such that difficulty with D-KEFS inhibition was associated with EF difficulties on the BRIEF-A self- and informant-report. 3) Controlling for FSIQ, D-KEFS Color-Word Inhibition switching and Verbal Fluency switching were positively correlated with the Adaptive Behavior Composite on the Vineland-II (both r’s > .44, p’s < .05). D-KEFS and BRIEF-A performance were not related to employment length, hours worked per week, or wages. D-KEFS was not related to overall quality of life (all r’s < .02, p’s > .05). BRIEF-A informant-report was significantly negatively correlated with informant-reported overall quality of life (r = -.55, p’s < .008), such that EF difficulties were related to lower quality of life.

Conclusions: Overall, adults with ASD performed similarly on the D-KEFS to adults at similar levels of cognitive ability. However, on ratings of everyday executive function, adults performed more poorly than predicted by intellectual ability. Overall, behavioral measures of EF and ratings of everyday EF were minimally correlated with each other suggesting that they are measuring different constructs. Both reports of everyday EF and standardized measures of EF contributed to our understanding of adult adaptive behavior and quality of life outcomes suggesting that both types of measures may be important to administer.