Addiction is a mental disorder within the mental health spectrum, and it matters

Substance use disorders and addictions are mental disorders deeply interconnected with other psychiatric conditions - and this connection is of fundamental importance. Although addictions are formally recognized as mental health disorders, they are often not addressed as such in research or clinical practice. Psychiatric research, clinical care, and treatment development remain largely organized along traditional diagnostic boundaries. While diagnostic classifications provide structure and clinical utility, it is increasingly evident that psychiatric diagnoses are neither fully separable nor independent entities. Despite extensive discussion on comorbidity, addictions are frequently excluded from broader conceptualizations of the intertwined nature of mental disorders. Yet, they share substantial commonalities with other psychiatric conditions across clinical presentation, psychopathology, genetic vulnerability, neurobiological mechanisms, socioenvironmental risk factors, and treatment strategies. Maintaining a conceptual divide between addictions and other psychiatric disorders reinforces diagnostic "tunnel vision," constraining our understanding of neuropsychopathology and contributing to persistent gaps in care and treatment accessibility. This narrative review examines the overlapping risk factors, clinical features, and therapeutic approaches that link addictions with other mental disorders. We argue that advancing psychiatric research and nosology requires a deliberate acknowledgement of these transdiagnostic overlaps and shared mechanisms. The challenge is particularly evident in the understanding and treatment of dual disorders. Progress will depend on integrative, collaborative frameworks that bridge scientific and clinical perspectives and foster dynamic feedback between empirical research and clinical practice. Recognizing mental disorders as interdependent systems may offer a more coherent and effective foundation for understanding and treatment.