Differential diagnosis and issues of nosology of disorders with affective and psychotic symptoms: clinical observation

Abstract

Based on the results of large-scale genomic studies, the psychotic continuum hypothesis suggests considering disorders characterized by primary psychotic symptoms as part of a single spectrum of neurodevelopmental disorders and implies the existence of a gradient of severity between affective disorders and schizophrenia, with increasing severity of psychotic epsodes and deficits. The continuum hypothesis explains the existence of the previously controversial diagnosis of schizoaffectivedisorder (SAD), which combines clinical manifestations of both schizophrenia and bipolar affective disorder: according to this hypothesis, schizoaffective disorder is assigned an intermediate position in the continuum. The common leading clinical criteria and genetic commonality on the one hand, and the absence of objective disease markers on the other significantly complicate the diagnostic search between the disorders with affective and psychotic symptoms, raising questions not only about their nosological relationships but also about the problem of finding methods of differentiation at early stages of disorder development. Promising tools for differential diagnosis include multifactorial analysis of parameters (genetic, clinical, and socio-demographic parameters, level of social functioning, response to prescribed psychopharmacotherapy), molecular phenotyping of profiles, and the search for laboratory, neuroimaging, and neurobiological markers of diseases. As of today, the main reliable approach in the differential diagnosis of these disorders remains the follow-up approach. The article presents a clinical case describing a 19‑year follow-up of a patient with clinically heterogeneous episodes of affective-delusional symptomatology combined with alcoholism and demonstrating the difficulty of diagnosing disorders with affective and psychotic manifestations, as well as the need for further research in this area.