Background: We tested the utility of the SWAN (Strengths and Weaknesses of ADHD Symptoms and Normal Behavior Rating Scale) for measuring attention-deficit/hyperactivity disorder (ADHD) traits in population-based genetics. We examined the convergent, predictive, and discriminant validity of the SWAN parent- and new youth report scale while creating norms and clinical cut-offs. We tested if high ADHD traits were associated with ADHD diagnosis and polygenic risk and if low ADHD traits pointed to another psychopathological phenotype or genetic risk. Methods: We collected parent- and youth-reported SWAN scores in a community sample (n=15,560; 6-18 years of age). Sensitivity-specificity analyses determined SWAN scores that discriminated a community ADHD diagnosis (n=972). Cut-offs were validated in a clinic sample (266 ADHD patients; 36 controls). We examined the relationship of SWAN scores with anxiety, obsessive-compulsive (OC) traits as well as ADHD, obsessive-compulsive disorder (OCD), and anxiety disorder using polygenic risk scores. Results: SWAN scores showed high convergent validity and distinguished ADHD participants with high sensitivity and specificity in the community sample. The community-based threshold discriminated ADHD clinic cases from controls with a sensitivity of 86% and specificity of 94%. High ADHD traits were associated with high anxiety, but not OC, traits. High SWAN scores and those above the community-based cut-off were only associated with ADHD polygenic risk. Conclusions: The SWAN is useful for genetic research because it predicts ADHD diagnoses with high sensitivity and specificity and is associated with ADHD polygenic risk. Cut-off values and norms are presented. Low ADHD traits were not associated with other psychopathology.

Utility of the SWAN Scale for ADHD Trait-Based Genetic Research: A Validity and Polygenic Risk Study