Development of executive functioning from childhood to young adulthood in autism spectrum disorder and attention-deficit/hyperactivity disorder: A 10-year longitudinal study.

OBJECTIVE: This 10-year longitudinal study investigated the developmental trajectories of executive functioning (EF) in individuals with autism spectrum disorder (ASD) or attention-deficit/hyperactivity disorder (ADHD), compared to typically developing (TD) individuals from childhood into young adulthood.

METHOD: There were 173 participants at baseline (T1; ASD = 38 (eight with co-occurring ADHD), ADHD = 85, TD = 50; M age = 11.7 years, SD = 2.1), 168 at 2-year follow-up (T2) and 127 at 10-year follow-up (T3). Participants were assessed with three neuropsychological tests aimed at capturing central components of EF: working memory/Letter-Number Sequencing Test (LNS), inhibition/Color-Word Interference Test, Condition 3 (CWIT3), and flexibility/Trail Making Test, Condition 4 (TMT4). Test results were analyzed using linear mixed models (LMM).

RESULTS: At baseline, the TD participants outperformed the ASD and ADHD participants on all three tests. From T1 to T2, the ASD participants had less improvement than the ADHD and TD participants on the LNS test ( p = .007 and .025, respectively), while having more improvement on the CWIT3 relative to the TD participants ( p = .027). From T2 to T3, the ADHD participants had less improvement on the LNS test than the ASD and TD participants ( p = .004 and .021, respectively).

CONCLUSIONS: The ASD and ADHD groups mainly displayed similar maturation on the neuropsychological measures, and displayed continuous impairment relative to the TD group. The need for support and facilitation of EF in school, workplace, and social arenas might continue into young adulthood among certain individuals with ASD and ADHD. (PsycInfo Database Record (c) 2021 APA, all rights reserved).