Two main pillars are essential for advancement in the understanding of complex illnesses such as schizophrenia and bipolar disorders. While the main advances in medicine and neuroscience currently come from progress in discovering new causal pathways or pathophysiological mechanisms, what is also needed, but often neglected, is parallel progress in refining the clinical paradigm.
In this respect, the original clinically based Kraepelinian distinction between dementia praecox and manic-depressive illness endures in the current classification systems of psychosis. Also, despite the fact that it continues to be the focus of much criticism,1 it still persists as the prevailing clinical model for neurobiological research.
Three main changes have notably modified the corresponding modern terms of the Kraepelinian dichotomy. First, Kraepelin's earlier unitary concept of manic depression, which included manic, circular, as well as recurrent depressive conditions, was changed to clearly differentiate bipolar from unipolar major depressive disorders.2 Second, Jaspers’ hierarchical principle stating that “schizophrenic” symptoms have diagnostic prominence over “mood” symptoms for diagnostic and prognostic purposes was inverted.3 Third, avolitional and dissociative symptoms, which were described as distinctive manifestations of dementia praecox, as well as further nuclear manifestations of schizophrenia, were de-emphasized in favor of Schneiderian first-rank symptoms, which greatly influenced current consensus classifications, such as International Classification of Diseases (ICD)-10 and the third and subsequent Diagnostic and Statiscal Manual (DSM) editions.4 It is not unfeasible that these changes might result in an unexpected reduction of “points of rarity” among psychosis subtypes by emphasizing common instead of distinguishing features.
Little is known about why some illness concepts survive longer than others, but 2 main factors seem to be involved. First, sociopolitical factors might support an “authority” bias in the existence of particular models.5 Second, there may be a lack of new scientific models that are needed for a paradigm shift that could overturn the previous models. Moreover, although current diagnoses are useful concepts,6 mounting evidence confirms that psychiatric disorders still cannot be conceptualized as definitively valid.
Heterogeneity and pleiotropy are hallmarks of the complex nature of psychoses at the clinical level7 and have further confounded neurobiological research on psychosis. Elsewhere, we emphasized that “… as long as we are not able to disentangle the heterogeneity question at the clinical level, it is unlikely that heterogeneity at the etiologic and pathophysiologic levels may be resolved.”8
General scepticism among new professionals about the value of careful clinical descriptions led some authors to question whether the DSM system might, paradoxically, lead to “the death of psychopathology.”9 DSM diagnoses emphasized reliability over validity and narrowed the scope of psychopathological symptoms and signs to those included in the manuals. Nonetheless, lack of interest in the clinical domain, such as psychopathology, is not an isolated phenomenon for psychiatry; one can find great similarities within other branches of medicine. For example, clinical history, signs and symptoms, and physical examinations are losing ground due to the development of complementary or instrumental exams. In fact, there is not only a psychopathological crisis but also a clinical crisis extending to the entire field of medicine.