A transdiagnostic approach to internalizing disorders: Examination of the relationships among cognitive vulnerability, neuroticism, and life events

The transdiagnostic approach aims to investigate the shared etiological and maintaining processes underlying different psychopathologies. In this context, depression and anxiety disorders are among the most frequently studied mental disorders and are classified within the internalizing disorder cluster in the (Hierarchical Taxonomy of Psychopathology) HiTOP model. The primary objective of this thesis is to examine, from a transdiagnostic perspective, the common risk factors involved in depression and anxiety disorders, which are considered internalizing disorders. Cognitive vulnerabilities stand out as significant shared risk factors in depression and anxiety disorders. The primary cognitive vulnerabilities include intolerance of uncertainty, rumination, fear of negative evaluation, anxiety sensitivity, dysfunctional attitudes, and negative cognitive style. Furthermore, negative life events and the personality dimension of neuroticism also play an important role in the development of psychopathologies within the scope of internalizing disorders. In line with this, the thesis aims to adapt the measurement of negative cognitive style to be culturally appropriate for the Turkish context, to test whether cognitive vulnerabilities can be modeled as a common latent factor, and to examine in greater depth the relationships between negative life events, neuroticism, cognitive vulnerabilities, and internalizing disorders. In the first study of the thesis, the Cognitive Style Questionnaire-Short Form, for which there had previously been no validity and reliability study in Turkey, was adapted into Turkish and its psychometric properties were examined. Based on analyses conducted with data from 374 participants, the scale was found to be a valid and reliable instrument for use in the Turkish sample. The second study of the thesis was carried out with a clinical sample consisting of 200 participants diagnosed with internalizing disorders. Within the scope of internalizing disorders, symptoms of major depressive disorder, generalized anxiety disorder, social phobia, and panic disorder were examined. The study utilized the Life Events Scale, Big Five Personality Inventory-Short Form, Cognitive Style Questionnaire-Short Form, Dysfunctional Attitudes Scale, Ruminative Response Scale, Intolerance of Uncertainty Scale, Anxiety Sensitivity Index-3, Brief Fear of Negative Evaluation Scale, Liebowitz Social Anxiety Scale, Panic-Agoraphobia Scale-Observer Form, Hamilton Anxiety Rating Scale, Hamilton Depression Rating Scale. Regression analyses were conducted to examine the relationships among cognitive vulnerabilities, neuroticism, negative life events, and internalizing disorders. Additionally, Structural Equation Modeling (SEM) was employed to model the six cognitive vulnerability factors under a single latent cognitive vulnerability variable, and to test the predictive roles of cognitive vulnerability and neuroticism on symptoms of internalizing disorders. The findings revealed significant associations between cognitive vulnerabilities, neuroticism, negative life events, and internalizing disorders. Finally, the results were discussed within the context of the existing literature, highlighting the significance and limitations of the study and offering recommendations for future research.