Comorbid Anxiety and Substance Use Disorders and Fear and Approach‐Based Traits in Bulimic Syndromes

OBJECTIVE: Bulimia nervosa and related syndromes (BN-S) are clinically heterogeneous and complex disorders. Frequent comorbidity with anxiety disorders (ADs) and substance use disorders (SUDs) implicates inherent fear- and approach-based tendencies in BN-S. This study aimed to clarify how comorbid ADs and SUDs, along with fear- and approach-based traits, influence the presentation and severity of BN-S. METHOD: Women (N = 399) with BN-S (n = 321) or no history of eating disorders (n = 78) completed the Eating Disorder Examination, Structured Clinical Interview for DSM-5 Disorders, Behavioural Inhibition System/Behavioural Activation System scales, and the Sensitivity to Punishment and Sensitivity to Reward Questionnaire. RESULTS: Diagnostic features, symptom frequencies, and eating pathology scores were not significantly affected by comorbidity with ADs or SUDs. Controlling for ADs, participants with BN-S scored significantly higher than controls on fear-based traits. Similarly, controlling for SUDs, individuals with BN-S showed elevated sensitivity to reward. Finally, elevated fear- and approach-based traits both contributed to elevated severity across a range of bulimic symptoms. CONCLUSION: Fear- and approach-based traits coexist in individuals with BN-S and were associated with the same symptoms. Although BN-S are currently placed within the Hierarchical Taxonomy of Psychopathology's internalising spectrum, findings indicate overlap with the externalising spectrum.