A dimensional approach to the psychosis spectrum between bipolar disorder and schizophrenia: The Schizo-Bipolar Scale

Abstract

Background There is increasing evidence for phenomenological, biological and genetic overlap between schizophrenia and bipolar disorder, bringing into question the traditional dichotomy between them. Neurobiological models linked to dimensional clinical data may provide a better foundation to represent diagnostic variation in neuropsychiatric disorders. Method To capture the interaction between psychosis and affective symptoms dimensionally, we devised a brief descriptive scale based on the type and relative proportions of psychotic and affective symptoms over the illness course. The scale was administered to a series of 762 patients with psychotic disorders, including schizophrenia, schizoaffective and psychotic bipolar disorder assessed as part of the Bipolar- Schizophrenia Network for Intermediate Phenotypes (B-SNIP) study. Results The resulting Schizo-Bipolar Scale scores across these disorders showed neither a clear dichotomy nor a simple continuous distribution. While the majority of cases had ratings close to prototypic schizophrenia or bipolar disorder, a large group (45% of cases) fell on the continuum between these two prototypes. . Conclusions Our data suggest a hybrid conceptualization model with a representation of cases with prototypic schizophrenia or bipolar disorder at the extremes, but a large group of patients on the continuum between them that traditionally would be considered schizoaffective. A dimensional approach, using the Schizo-Bipolar Scale, characterized patients across a spectrum of psychopathology. This scale may provide a valuable means to examine the relationships between schizophrenia and psychotic bipolar disorder.

The Dynamics of DNA Methylation in Schizophrenia and Related Psychiatric Disorders

“…The origins of the psychotic symptoms of BP+ are most likely the consequence of the underlying mood disorder (mania) depending on the nature of the delusions and hallucinations described by the patient at clinical presentation. Collectively, these psychiatric disorders are complex diseases of brain function and accumulating evidence supports an overlap between the biological and genetic data associated with SZ and BP+ (Keshavan et al, 2011). Moreover, we suggest that altered DNA methylation dynamics likely underlie the pathogenesis of psychotic symptoms.…”

“…Each of these psychiatric disorders is distinct and characterized by additional symptoms. The positive symptoms and cognitive impairment associated with SZ and BP disorder with psychosis (BP+ ) show considerable overlap in clinical presentation (Potash and Bienvenu, 2009;Keshavan et al, 2011;Ivleva et al, 2012). The origins of the psychotic symptoms of BP+ are most likely the consequence of the underlying mood disorder (mania) depending on the nature of the delusions and hallucinations described by the patient at clinical presentation.…”

Hemispheric lateralization abnormalities of the white matter microstructure in patients with schizophrenia and bipolar disorder

“…[13][14][15][16][17][18] Clinically, the boundaries between schizophrenia and BD can be blurred early in the illness and even over time. 19,20 Given the overlap of psychotic symptomatology and risk gene loci, 21,22 direct comparisons of hemispheric lateralization in patients with schizophrenia and BD can yield insight into common and different pathophysiology underlying the shared and unique clinical features of these disorders. More specifically, if we build on the assumption that hemispheric abnormalities reflect neurodevelopmental aberrancy in indi viduals with psychosis, 2 then shared lateralization abnormal ities in neural substrates across schizophrenia and BD could represent a trait rather than a state feature of psychosis.…”

Multivariate analysis reveals genetic associations of the resting default mode network in psychotic bipolar disorder and schizophrenia

“…genetics | BSNIP | architecture | molecular S chizophrenia (SZ) and psychotic bipolar disorder (PBP) are common, serious, heritable, genetically complex illnesses, sharing multiple characteristics, including risk genes and abnormalities in cognition, neural function, and brain structure (1)(2)(3)(4). However, despite recent advances, their underlying biological mechanisms are largely undetermined and may be shared across the two diagnostic groups.…”

“…According to the "common disease common variant" (CDCV) model, one would expect both common and unique quantitative/heritable traits associated with the above syndromes, regulated by these underlying genes, to provide a good starting point for understanding the etiology of SZ and BP. Because definitions of psychiatric diseases are based on clinical phenomenology and lack biological validity (2,8) a recent strategy has been to use intermediate phenotypes (9,10) to elucidate quantitative/mechanistic aspects of the underlying disease processes, thereby reducing phenotypic heterogeneity and increasing association power (9,11,12). Various properties of intrinsic networks derived from resting-state functional MRI (RS-fMRI) connectivity are promising putative endophenotypes (4,13).…”