Personality Traits in Adolescents with ADHD: Insights into Dimension Evaluation and Clinical Implications Using the Personality Inventory for the DSM-5 Questionnaire

Background/Objectives: Attention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder characterized by inattention, hyperactivity, and impulsivity, often persisting into adolescence and adulthood, with significant impacts on social, academic, and occupational functioning. Emerging research highlights the role of personality traits in ADHD, suggesting their influence on symptom presentation, functional impairments, and treatment adherence. This study aims to investigate maladaptive personality domains and traits in adolescents with ADHD using the Alternative Model of Personality Disorders (AMPD) framework and the Personality Inventory for DSM-5 Short Form (PID-5-SF), with a particular focus on the differences among same-sex peers and differences from typically developing peers. Methods: This study included 30 ADHD and 25 TD adolescents aged 11–17 (12.6 ± 2.1 vs. 14.9 ± 1.7; p < 0.001), recruited at IRCCS Centro Neurolesi “Bonino Pulejo”. Participants underwent clinical assessments, cognitive evaluation, and standardized rating scales, with maladaptive personality traits measured using the PID-5-SF. Chi-squared and Mann–Whitney U tests were used to compare the two groups, as appropriate. Results: ADHD adolescents showed significantly higher scores than TD peers in restricted affectivity (p = 0.007), distractibility (p = 0.001), impulsivity (p = 0.049), irresponsibility (p = 0.036), hostility (p = 0.046), perseveration (p = 0.010), submissiveness (p = 0.023), and risk-taking (p = 0.032). Among personality domains, disinhibition was significantly higher in the ADHD group (p = 0.002), while detachment approached significance. Female ADHD participants scored higher than TD females in restricted affectivity, distractibility, and risk-taking. Conclusions: These findings suggest that maladaptive personality traits play a key role in ADHD during adolescence, highlighting the need for tailored interventions. Integrating personality assessment into clinical practice may enhance diagnostic accuracy and support more effective, individualized treatment strategies.