Biological, Life Course, and Cross-Cultural Studies All point Toward the Value of Dimensional and Developmental Ratings in the Classification of Psychosis

Division of Psychological Medicine and Psychiatry, Institute of Psychiatry, King's College London, UK.
Schizophrenia Bulletin (Impact Factor: 8.45). 08/2007; 33(4):868-76. DOI: 10.1093/schbul/sbm059
Source: PubMed


The diagnostic criteria for schizophrenia in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) are based on the premise that it is a discrete illness entity, in particular, distinct from the affective psychoses. This assumption has persisted for more than a century, even though patients with a diagnosis of schizophrenia show a wide diversity of symptoms and outcomes, and no biological or psychological feature has been found to be pathognomonic of the disorder. However, there has been sustained, and indeed growing, criticism of the concept. For example, writing about the diagnosis of schizophrenia more than a decade ago,2 one of Britain's most sophisticated nosological experts, Ian Brockington, enjoined "It is important to loosen the grip which the concept of 'schizophrenia' has on the minds of psychiatrists. Schizophrenia is an idea whose very essence is equivocal, a nosological category without natural boundaries, a barren hypothesis. Such a blurred concept is 'not a valid object of scientific enquiry'."3 Should Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition(DSM-V), persist with the neo-Kraepelinian concept of schizophrenia with all its defects, or should it deconstruct psychosis into its component dimensions? In this article, we will address the question by considering 2 main themes, firstly, the role of culture and ethnicity in the diagnosis of psychosis, and secondly, a life course approach to understanding psychosis. We will then discuss whether more progress would be achieved in DSM-V by abandoning the familiar categorical system and instead moving to a dimensional system which rates both developmental impairment and symptom factor scores. However, we will begin by briefly reviewing the recent history of the classification of the psychoses.

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Article: Biological, Life Course, and Cross-Cultural Studies All point Toward the Value of Dimensional and Developmental Ratings in the Classification of Psychosis

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    • "Moreover, when clinical samples of patients with psychosis were analyzed, several differences between countries and culture emerged. For example, prognosis, diagnosis, time of hospitalization, onset, intervention, and risk for psychosis varied across groups (Susser and Wanderling, 1994; Sartorius et al., 1996; Dutta et al., 2010; Moriwaki et al., 2013). These cross-cultural findings could be of crucial relevance in psychosis research; for instance, they could be of value for determining cut-off points for detecting participants at risk for psychosis in the context of a given culture. "
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    ABSTRACT: The main goal of this study was to examine the cross-cultural invariance of the factor structure of the Schizotypal Personality Questionnaire (SPQ) (Raine, 1991) in two large samples of Spanish and American young adults. The final sample was made up of 2313 college students (508 men, 22%). Their mean age was 20.5 years (S.D. ¼3.2). The results indicated that the Stefanis et al. (2004) four-factor model yielded the best goodness-of-fit indices compared to alternative models. Moreover, the results support configural, metric, and partial measurement invariance of the covariances of the SPQ across the two samples. The finding of measurement equivalence across cultures provides essential evidence of construct validity for the schizotypy dimensions and of the cross-cultural validity of SPQ scores. The finding of comparable dimensional structures in cross-cultural samples lends further support to the continuum model of schizotypy and schizophrenia spectrum disorders. Future studies should continue to examine the validity of scores on the SPQ and other schizotypy measures and their variation or consistency across cultures.
    Psychiatry Research 10/2014; 220(3). DOI:10.1016/j.psychres.2014.06.050 · 2.47 Impact Factor
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    • "Schizophrenia is a heterogeneous mental disorder with various degrees of overlap with other diseases, such as bipolar disorder (Peralta and Cuesta, 2001; Dutta et al., 2007). It comprises several genetic, neurophysiological, and behavioral aspects (Lisman et al., 2008; Howes and Kapur, 2009; Javitt, 2009) whose co-occurrence, and relative dominance, vary between patients and over the course of the illness. "
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    ABSTRACT: In the Ebbinghaus illusion, a circle surrounded by smaller circles is perceived as larger than an identical one surrounded by larger circles. The illusion is reportedly weaker in individuals with (disorganized) schizophrenia or schizotypy than in controls, a finding that has been interpreted as evidence that both schizophrenia and schizotypy involve reduced contextual integration. In support of this view, we show that the Ebbinghaus illusion also decreases, in the general population, with cognitive-perceptual schizotypal traits (measured with both the cognitive-perceptual subscale of the Schizotypal Personality Questionnaire-Brief and the Magical Ideation scale). Our results were strong and separately replicable in different within-subjects and between-subjects conditions. However, a mediation analysis revealed that the reduction of the Ebbinghaus illusion was (statistically, hence without implying a causal relationship) entirely due to increased judgment time, i.e., the time subjects took to complete size comparisons. Judgment time increased with the strength of cognitive-perceptual schizotypal traits, but subjects with longer judgment times had smaller illusions regardless of these traits. We argue that there are at least two possible accounts of our results. Reduced contextual integration might be due to a reduced ability to integrate context, as previously suggested; alternatively, it could be due to a reduced tendency to integrate context-that is, to a detail-oriented processing style. We offer predictions for future research, testable with a deadline experiment that pits these two accounts against one another. Regardless of which account proves to be best, our results show that contextual integration decreases with cognitive-perceptual schizotypal traits, and that this relationship is mediated by judgment time. Future studies should thus consider either manipulating or measuring this time.
    Frontiers in Psychology 06/2013; 4(343):343. DOI:10.3389/fpsyg.2013.00343 · 2.80 Impact Factor
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    • "As such, it is important to explicitly include dimensional assessments of the core symptoms of psychotic disorders in order to identify pertinent variability. Therefore, the most useful current approach for the classification of schizophrenia (SZ), other psychotic (OP), and mood disorders may be the complementary use of categorical and dimensional representations of functional psychoses (Salokangas, 2003; Brown and Barlow, 2005; Dikeos et al., 2006; Dutta et al., 2007; Helzer et al., 2008; van Os, 2009; Kamphuis and Noordhof, 2009). "
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    ABSTRACT: Innovations in DSM5 include dimensional diagnosis of schizophrenia (SZ) and other psychotic (OP) disorders using the symptom severity scale (SS-DSM5). We evaluated the psychometric properties and diagnostic validity of the SS-DSM5 scale using cross-sectional design, and a convenience unselected sample of 314 inpatients and outpatients with SZ/OP and mood disorders who received standard care in routine clinical practice. The SS-DSM5 scale, the Clinical Global Impression-Severity scale (CGI-S), Positive and Negative Syndrome Scale (PANSS), and Bech-Rafaelsen Mania Scale (BRMS) were administered. Factor structure, reliability, internal consistency, convergent and diagnostic ability of the DSM5-SS was evaluated. Factor analysis indicated two latent factors underlying the SS-DSM5 (Psychotic and Deficit sub-scales). Cronbach's alpha was >0.70. Convergent validity of the SS-DSM5 was highly significant. Patients with SZ/PO disorders were correctly diagnosed (77.9%) using the SS-DSM5 scale (72% using PANSS). The agreement of the diagnostic decisions between the SS-DSM5 and PANSS was substantial for SZ/PO disorders (Kappa k was 0.75, P<0.001). Classifying participants with SZ/PO versus mood disorders using SS-DSM5 provided a sensitivity of 95%, and specificity of 34%. Thus, this study suggests that the SS-DSM5 has acceptable psychometric properties and that its use in clinical practice and research is feasible in clinical settings. The dimensional option for the diagnosis of schizophrenia and related disorders using SS-DSM5 is discussed.
    04/2013; 208(1). DOI:10.1016/j.psychres.2013.02.029
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