Do High and Low Extremes of ADHD and ASD Trait Continua Represent Maladaptive Behavioral and Cognitive Outcomes? A Population-Based Study

Objective: Attention deficit hyperactivity disorder (ADHD) and autism spectrum disorders (ASD) are thought to reflect the high, symptomatic extreme of quantitative trait continua. However, extreme deviations in either direction on disorder continua, high and low, may both represent maladaptive behavioral and cognitive outcomes. We aimed to test this hypothesis. Method: In a population sample of 378 children, ADHD and ASD traits were rated by parents on questionnaires that provide resolution at high and low extremes of the ADHD and ASD trait continua. ADHD and ASD traits were related to parent-ratings of internalizing and externalizing behavior problems and tests of cognitive functioning using polynomial regression. Results: The low ends of the ADHD and ASD trait continua were related to fewer behavior problems and better cognitive functioning than symptomatic ends. Conclusion: Studying the correlates of the low continuum ends may deepen our understanding of the mechanisms underlying adaptive behavioral and cognitive outcomes

Homogeneous Combinations of ASD-ADHD Traits and Their Cognitive and Behavioral Correlates in a Population-Based Sample

Objective: Autism Spectrum Disorders (ASD) and ADHD are assumed to be the extreme manifestations of continuous heterogeneous traits that frequently co-occur. This study aims to identify subgroups of children with distinct ASD-ADHD trait profiles in the general population, using measures sensitive across both trait continua, and show how these subgroups differ in cognitive functioning. Method: We examined 378 children (6-13 years) from a population-based sample. Results: Latent class analyses (LCA) detected three concordant classes with low (10.1%), medium (54.2%), or high (13.2%) scores on both traits, and two discordant classes with more ADHD than ASD characteristics (ADHD > ASD, 18.3%) and vice versa (ASD > ADHD, 4.2%). Findings suggest that ASD and ADHD traits usually are strongly related in the unaffected population, and that a minority of children displays atypical discordant trait profiles characterized by differential visual-spatial functioning. Conclusion: This dissociation suggests that heterogeneity in ASD and ADHD is rooted in heterogeneity in the lower unaffected end of the distribution