Objectives The aim of this study was to evaluate the structural relationships between behavioral brain systems, disgust sensitivity, and obsessive-compulsive disorder using structural equation modeling. It is assumed that the behavioral brain systems and disgust sensitivity in interaction with each other will lead to obsessive-compulsive disorder. Despite the prominence of this model, not enough research has been done to assess its experimental. Methods In a descriptive-correlation study, a sample of 340 students from Tabriz University was selected using cluster sampling method. Participants responded to Inventory system activation / inhibition of behavior (Carver and White, 1994), The Disgust Sensitivity Scale, Obsessive Compulsive Inventory-Revised (OCI-R). Data were analyzed using Structural Equation Modeling (SEM). For statistical analysis, spss V. 22 and LaserL 85.9 were used to classify, process and analyze the data and to investigate the hypotheses of the research. Results The evaluation of hypothetical model with fit indexes demonstrated that the hypothetical model fits the measurement model (CFI=0.96, NFI=0.94, and RMSEA=0.076). BIS and BAS with standardized coefficients of 0.264 and -0.241, respectively, have a significant effect on obsessive-compulsive disorder by the mediation of disgust sensitivity at the P˂0.05 level. Conclusion The result, supporting the theoretical model for obsessive-compulsive disorder, proposes a suitable framework for etiology of the disorder. Accordingly, high sensitivity of BIS and low sensitivity of BAS by the mediation of disgust sensitivity due to an increase in the symptoms of OCD.

Objectives Generalized anxiety disorder and depression, one of the common problems in childhood and adulthood is associated with many problems in the field of health. This study aimed to investigate the mediating role of rumination in the relationship among Intolerance of Uncertainty (IU) and symptoms of depression and General Anxiety Disorder (GAD). Methods In this descriptive correlational study, a sample of 250 students from Iran University of Medical Sciences were selected using cluster sampling method. The participants responded to intolerance of uncertainty scale and rumination scale, Generalized Anxiety Disorder Questionnaire Inventory-revised (GAD-Q-IV), and Beck depression inventory. The obtained data were analyzed using Structural Equation Modeling (SEM). For statistical analysis, SPSS V. 22 and LISREL 85.9 were used to classify, process, and analyze the data and to investigate the hypotheses of the research. Results The evaluation of hypothetical model with fit indexes demonstrated that the hypothetical model fits the measurement model (CFI=0.98, NFI=0.96, and RMSEA=0.060). Structural relations analysis also indicated intolerance of uncertainty indirectly through rumination over depression and directly and indirectly general anxiety disorder. Conclusion Thus, based on the current research findings, rumination has a mediating role in relationship between intolerance of uncertainty and symptoms of depression and general anxiety disorder. Considering these dimensions, the employed mechanisms can be useful in developing efficacious preventive and therapeutic interventions for depression.