Behavioral manifestations of executive functioning in Swedish youth with ADHD, autism, and psychiatric comorbidity: a comparative analysis with community controls

While several rating scales reliably and cost-effectively assess behavioral executive functioning (EF) in youths with neurodevelopmental disorders (NDDs), questions remain about the impact of comorbidities and dual NDDs on EF as measured by these scales in clinical samples. This study compared behavioral EF profiles among youths with NDDs, both with and without psychiatric comorbidities, non-NDDs (e.g. anxiety), and controls, as well as youths with single versus dual NDDs. The comparisons were made using the Swedish version of the Behavior Rating Inventory of Executive Function (BRIEF-2) parent form. Participants included 79 youths (mean [SD] age 12.1 [3.0]; 50.6% girls) diagnosed with various psychiatric conditions, and 151 matched controls (mean [SD] age 12.4 [2.8]; 51.7% girls). Results showed significant differences with very large effect sizes in all behavioral EF domains among youths with NDDs, regardless of whether they had non-NDD psychiatric comorbidities, compared to youths with non-NDDs or controls. The latter two groups differed in six of eight behavioral EF domains, with the Shift domain showing the largest effect size (Cohen's d = 0.94). Surprisingly, no significant differences were found between the NDD-only group and the NDD group with non-NDD psychiatric comorbidities. Youths with dual NDDs had more deficits in four of the nine behavioral EF domains compared to those with a single NDD, with the Shift domain again showing the largest effect size (Cohen's d = 0.91). This study highlights the essential role of NDD in distinguishing clinically significant parent-rated behavioral EF deficits in youths, regardless of other psychiatric diagnoses.