The Common Structure of Dimensional Personality Disorder and Attention Deficit Hyperactivity Disorder

Background: Common and distinct features of personality disorders (PDs) and attention deficit hyperactivity disorder (ADHD) have long been the focus 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. To date, no study has examined the common structure of dimensional PD, according to the alternative DSM-5 model for PDs (personality functioning and pathological personality traits), and ADHD.Methods: In a preregistered study, a sample of adults seeking mental health support (n = 2,567) completed self-report measures assessing personality functioning, pathological personality traits (negative affectivity, detachment, antagonism, disinhibition, psychoticism, and anankastia), and ADHD (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.Results: ADHD components showed strong correlations with personality functioning and moderate-to-strong associations with pathological personality traits, particularly disinhibition. Disinhibition remained the only trait domain substantially correlated with ADHD after control-ling for a general personality pathology factor. In exploratory models, ADHD components 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 that ADHD has substantial overlap with dimensional PD. Clinically, individuals with ADHD may benefit from integrated assessments of personality functioning and pathological personality traits, and from interventions addressing personality pathology.