Communication across Autism, ADHD, and non-clinical groups: Examining ASD and ADHD traits from a dimensional perspective

Communication difficulties are common among youth with Autism Spectrum Disorder (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD). However, traits associated with ASD and ADHD are continuously distributed in the general population, raising the question of whether communication differences are better explained by diagnostic categories or by dimensional trait variation. This study included 493 Italian children and adolescents aged 7-16 years old (M = 11.35; SD = 2.64): 147 (126 boys) with ASD without intellectual disability, 105 (88 boys) with ADHD, and 241 (203 boys) non-diagnosed peers. Parents completed standardized measures assessing communication skills, ASD and ADHD traits. Both clinical groups showed significant communication difficulties compared to non-diagnosed peers, with large effect sizes (ASD-ND: d=1.66; ADHD-ND: d=-1.00). Importantly, results supported a dimensional model: individual differences in communication were more effectively explained by variation in ASD and ADHD traits across the entire sample (BIC = 4151.39) than by diagnostic group membership alone (BIC = 4324.75). Both trait dimensions independently predicted communication challenges across clinical and non-clinical population, though ADHD traits had a slightly weaker effect. This perspective provides a more nuanced understanding of how ASD and ADHD traits may relate to communication challenges across the general population, extending beyond the boundaries of clinical diagnosis.