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: 8.61). 08/2007; 33(4):868-76. DOI: 10.1093/schbul/sbm059
Source: PubMed

ABSTRACT 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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    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 · 2.68 Impact Factor
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    ABSTRACT: There is accumulating epidemiological evidence of cross-ethnic differences in relation to schizophrenia’s incidence and prevalence. However, there is a dearth of information about the manifestations of cultural differences of schizophrenia’s symptoms. This thesis aims to bridge the gap in the knowledge on the relationship between cross-cultural differences and schizophrenia. Throughout this thesis, I explore the similarities and dissimilarities of the content of clinical manifestation across cultures. I also examine and further develop epidemiological and clinical issues. First, I perform a qualitative systematic review which includes 26 publications. This is followed by findings from a statistical analysis of a mental health population of 860 patients in Brent, North London. Lastly, I report on results from a semi-structured mental health questionnaire that was devised and disseminated to 48 mental health professionals in London. Results indicate that for ethnic groups that experience a higher incidence of schizophrenia they also tend to display more positive or first rank symptoms. These ethnic groups that experience higher schizophrenia also belong to cultures that culturally legitimise an externalization of their distress. On the other hand, it was found that cultures that internalize their distress experience lower schizophrenia incidence. My research further demonstrates that schizophrenia’s interpretations are heavily reliant on the diagnosers’ own cultural background, and on the degree to which the externalization of a symptom is tolerable in that context. Evidence of intra-cultural diversity in the clinical settings furthermore posits future recommendations of the importance of achieving higher cultural competence.
    10/2012, Degree: PhD Psychology Research, Supervisor: Dany Nobus

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