Dopamine system as a mediator between psychological symptoms and relapse tendency: a cross-sectional study in women undergoing compulsory rehabilitation in Zhengzhou, China

To examine whether psychological symptoms influence relapse propensity among individuals with drug dependence through the dopamine (DA) system, after controlling for confounders such as age. Ninety Women Individuals in Compulsory Drug Rehabilitation, aged 18–60 years, were enrolled. Key measures included psychological status [assessed via the Montreal Cognitive Assessment (MoCA), Self-rating Depression Scale (SDS), Symptom Checklist-90 (SCL-90), and Pittsburgh Sleep Quality Index (PSQI)]; physiological indicators [blood concentrations of serotonin (5-HT), interleukin-6 (IL-6), gamma-aminobutyric acid (GABA), and dopamine (DA)]; and socio-demographic and drug-use characteristics (age, education, marital status, years of drug use, etc.). Relapse propensity was quantified using a Relapse Propensity Scale score. Data analysis included Pearson correlation, stepwise multiple linear regression, and mediation analysis using the bootstrap method (PROCESS Model 4). Bivariate analysis revealed that relapse propensity was significantly correlated with age ( r = 0.322, p < 0.01), SCL-90 GSI ( r = 0.261, p < 0.05), and DA concentration ( r = 0.341, p < 0.01). Stepwise regression identified DA concentration ( β = 0.321, p = 0.001) and age ( β = 0.301, p = 0.002) as the only significant independent predictors, jointly accounting for 18.8% of the variance in relapse propensity (adjusted R 2 = 0.188). Crucially, mediation analysis confirmed a significant indirect effect of SCL-90 on relapse propensity through DA (indirect effect = 0.018, 95% CI [0.005, 0.035]). The direct effect was non-significant ( p = 0.170), indicating full mediation. The mediated effect accounted for 35.6% of the total effect. This study indicates that psychological symptoms indirectly increase relapse propensity in Compulsory Drug Rehabilitation by elevating DA concentration. DA fully mediates the relationship between psychological symptoms and relapse propensity. Age independently predicts relapse propensity but does not act through the DA system. These findings support an integrated “psychological–neurobiological” intervention approach. In clinical practice, relapse prevention strategies should combine psychological symptom management with DA system modulation, alongside age-tailored interventions.