Personality-based subgroup identification and psychological symptom patterns in adolescent male new psychoactive substance users: implications for targeted intervention

BACKGROUND/OBJECTIVES: Adolescent new psychoactive substance (NPS) users represent a high-risk population with complex psychological needs that remain insufficiently characterized, limiting the development of targeted rehabilitation interventions. This study aimed to (1) characterize the personality trait profiles and psychological symptom patterns of adolescent NPS users undergoing compulsory drug rehabilitation relative to normative standards; (2) identify empirically derived personality-based subgroups within this population; and (3) examine differential psychological symptom patterns across identified subgroups to inform precision intervention design. METHODS: A cross-sectional study was conducted with 60 adolescent male participants (mean age = 17.2 ± 1.9 years) recruited from a compulsory drug rehabilitation facility in Shandong Province, China. Participants completed a multimodal assessment battery comprising Cattell's 16 Personality Factor Questionnaire (16PF), the Personality Diagnostic Questionnaire-4+ (PDQ-4+), and the Symptom Checklist-90-Revised (SCL-90-R). Personality-based subgroups were identified using a two-stage cluster analysis (Ward's method followed by K-means), with cluster quality evaluated via Average Silhouette Width and split-sample Adjusted Rand Index. Between-cluster differences in psychological symptom profiles were examined using one-way ANOVA with Tukey post-hoc comparisons. Hierarchical multiple regression identified independent personality predictors of overall psychological distress (SCL-90-R Global Severity Index, GSI). RESULTS: Fourteen of 16 personality factors deviated significantly from Chinese adolescent norms (all corrected p < .05), with the largest deviations observed for Tension (Q4; d = 1.38), Rule-Consciousness (G; d = 1.30↓), Apprehension (O; d = 1.24), and Emotional Stability (C; d = 1.13↓). Overall psychological distress was pervasive, with 81.7% of participants exceeding the GSI clinical significance threshold (GSI ≥ 1.0; mean GSI = 1.52 ± 0.43). Paranoid Ideation emerged as the most severely elevated SCL-90-R dimension (d = 1.39), followed by Interpersonal Sensitivity (d = 1.09) and Anxiety (d = 1.02). Cluster analysis identified three empirically stable personality-based subgroups: Dysregulated-Hostile (n = 22, 36.7%), Anxious-Withdrawn (n = 21, 35.0%), and Impulsive-Sensation-Seeking (n = 17, 28.3%; Average Silhouette Width = 0.58; split-sample ARI = 0.71). The three clusters demonstrated clinically meaningful differential symptom profiles: the Dysregulated-Hostile cluster was characterized by elevated Hostility and Paranoid Ideation; the Anxious-Withdrawn cluster by elevated Anxiety, Depression, and Obsessive-Compulsive symptoms; and the Impulsive-Sensation-Seeking cluster by relatively lower overall distress with elevated personality disorder tendencies. Hierarchical regression revealed that 16PF personality factors explained an additional 48.7% of variance in GSI beyond demographic covariates (ΔR² = 0.487, ΔF(6, 49) = 14.38, p < .001), with Tension (Q4; β = 0.318), Emotional Stability (C; β = -0.312), and Apprehension (O; β = 0.287) as the strongest independent predictors. CONCLUSIONS: Adolescent NPS users in compulsory rehabilitation present a distinctive high-risk personality configuration and a substantial psychological distress burden that is not uniformly distributed across the population. Three empirically derived personality-based subgroups with differential symptom profiles provide preliminary, hypothesis-generating evidence that should be validated in a larger, multisite cohort before informing the development of differentiated, precision intervention strategies. Personality assessment at treatment intake-particularly targeting Tension, Emotional Stability, and Apprehension-offers clinically meaningful predictive information for distress severity that substantially exceeds demographic screening alone. These findings complement the gut microbiota-exercise intervention framework being developed in our companion, currently in-press trial and represent a critical step toward a precision medicine model for adolescent NPS rehabilitation that integrates personality-based stratification with physiologically targeted exercise interventions.