The Common Structure of Dimensional Personality Disorder and Attention Deficit Hyperactivity Disorder Symptoms in a Large Clinical Sample of Adults

Background: Common and distinct features of personality disorders (PDs) and attention deficit hyperactivity disorder (ADHD) have long been the subject of research. However, most studies relied on categorical rather than dimensional models, which are becoming increasingly integrated into contemporary psychiatric nosology and may offer more nuanced insights. The present study aimed to examine the common structure of dimensional PD, according to the alternative DSM-5 model for PDs (personality functioning and pathological personality traits), and ADHD symptoms. Methods: In a preregistered study, a clinical sample of adults (n = 2,567) completed self-report measures assessing personality functioning, pathological personality traits (negative affectivity, detachment, antagonism, disinhibition, psychoticism, and anankastia), and ADHD symptoms (inattention, hyperactivity/impulsivity, and executive functioning). Structural equation modeling was employed to examine the latent structure and shared variance among these constructs using confirmatory and exploratory factor models, including models with a general factor of personality pathology. Results: ADHD symptoms were strongly correlated with personality functioning and showed moderate-to-strong associations with pathological personality traits, with disinhibition remaining the only trait domain substantially correlated with ADHD symptoms after controlling for a general personality pathology factor. In exploratory models, ADHD symptoms showed two distinct loading patterns among disinhibition facets: one factor was mainly defined by inattention and distractibility, with additional but weaker loadings of hyperactivity/impulsivity, whereas the other reflected executive functioning and irresponsibility. Conclusion: The findings suggest substantial overlap between dimensional PD and ADHD symptoms. In clinical practice, individuals with suspected PD or ADHD may benefit from integrated dimensional assessments of both conditions.