Nosological Perspectives on Schizophrenia Detection and Prevention

As scholars discuss the possibility of changing the name of schizophrenia, an opinion piece in Frontiers in Psychiatry states that it is essential, for both clinical practice and research, to conduct an overview of possible nosological perspectives of schizophrenia.

The current literature on psychosis debates the merits and weaknesses of the concept of trans-nosographic psychosis, which holds that psychosis is not limited to any specific psychotic disorder, but instead represents a continuous expression across a spectrum and can be perceived as an extreme expression of quantitative traits that are distributed across the general population.

The broad psychotic spectrum concept proposes that approximately 10% to 20% of the population experiences subtle alterations in processing stimuli that give rise to paranoid feelings or negative affective states (microphenotype), some of which persist and occur along with other symptoms such as anxiety and depression, and lead to noticeable distortion of reality (extended phenotype). The co-presence of reality distortion and affective dysregulation increases the individual risk of psychotic disorder onset (illness macrophenotype), manifesting as a network of causally impactful symptoms. In this perspective, schizophrenia represents a rare, poor-prognosis disorder within a broader spectrum of other disorders.

This trans-nosographic model should be compared with the clinical high risk (CHR) paradigm, which is used to identify individuals at risk of psychosis. CHR was developed with the description of 3 possible prodromal syndromes, including genetic risk and deterioration (GRD), attenuated positive symptom syndrome (APS), and/or brief intermittent psychotic syndrome (BIPS). The transition rate from a CHR state to psychosis is approximately 20% in 1 year and 36% in 3 years, with 60% eventually developing along the schizophrenia spectrum and the remaining 40% developing atypical and mood-related psychosis.

Though the CHR model does highlight the large prevalence of attenuated psychotic symptoms, it has poor predictive specificity for schizophrenia because only 10% to 15% of those classified as CHR evolve toward schizophrenia. This is primarily because CHR excludes all negative symptoms and most disorganized symptoms, restricting schizophrenia primarily to its overt delusional–hallucinatory forms. The dual-output model of transition vs no transition has been the breeding ground for trans-nosographic views of attenuated psychosis. In the midst of the debate, the main point is no longer whether CHR status can predict schizophrenia, but where it is predictive of psychotic spectrum disorders or other non-psychotic conditions. If the spectrum approach in the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) is embraced, a discussion around the benefits of changing the schizophrenia name emerges, or possibly just the concept of schizophrenia itself.

The researchers outline 3 possible perspectives on the debate:

• Schizophrenia is a combination of genetic and environmental interplay leading to poor outcomes and in the trans-nographic context, would denote the most extreme outcomes of serious mental illness.

• Regardless of pathogenetic and outcome paths, schizophrenia is the delusional–hallucinatory expression of the psychotic spectrum characterized by the expression of positive symptoms. This notion reflects the more recent DSM and may be extended to schizoaffective disorders and certain forms of mania.

• The etiopathogenesis of schizophrenia is strongly linked to neurodevelopmental disorders with disorganized/cognitive and negative symptoms used to detect the illness before the development—and regardless—of full-blown positive psychotic symptoms.

When it comes to early detection and prevention, the first perspective implies a general model of universal prevention of severe psychopathology; the second model implies schizophrenia as detectable through CHR; and the third suggests the consideration of creating a prodromal model of schizophrenia by referring to criteria including both blunted affect, cognitive/disorganized, and social/academy withdrawal symptoms, and intermediate phenotypes like speed of processing and impaired social cognition.

The investigators concluded, “While the first two options might seem the smoothest and less problematic ones, the last option might be the most promising in terms of improving scientific knowledge and offering the opportunity of better encompassing effective strategies for early identification.”

Reference

Comparelli A, Raballo A, Pompili M, Galderisi S. Beyond the transnosographic emphasis on psychosis: Nosological perspectives on schizophrenia and its prevention [published online September 18, 2019]. Front Psychiatry. doi: 10.3389/fpsyt.2019.00666