Current status and challenges of the psychiatric nosography. Is there a conflict between expectations and evidence?

Since the first attempts of psychiatric nosography, dating back to 1763, the difficulties of finding well-defined criteria for categorizing entities in the field of psychopathology have been observed by scientists. The complexity of psychiatric clinical manifestations, their great interindividual variability, the lack of irrefutable evidence-based theories regarding the pathogenesis of mental and behavioral disorders, and the differences in cultural perspectives on the boundaries between normality and pathology, all of these and many other challenges make it difficult for clinicians and researchers to construct an unanimously acceptable nosographic system. This narrative review aims to explore the strengths and limitations of the main nosographic systems in use worldwide and of some of those that are still undergoing various stages of validation, starting from their practical utility and the theoretical concepts on which they are founded. Phenomenologically oriented nosographic systems, classifications based on psychodynamic theories, models focused on translational data, taxonomies built on purely clinical principles, and nosographies that combine specific cultural aspects with internationally recognized diagnoses have been analyzed. The evidence supporting these theoretical models varies greatly in their principles (statistical, biological, psychological, and cultural variables being involved) and validity, indicating that the practitioners’ expectations from existing nosographies should be moderate. What is important to remember when comparing this multitude of nosographic models is the need to adapt the framework to the purpose, namely to operate with that diagnostic-interpretative model which is the most appropriate to the actual context, whether it is clinical activity, pharmacological research, psychotherapy, or epidemiological investigation.