Competing Definitions of Schizophrenia: What Can Be Learned From Polydiagnostic Studies?

Schizophrenia Bulletin (Impact Factor: 8.45). 10/2007; 33(5):1178-200. DOI: 10.1093/schbul/sbl065
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The contemporary diagnoses of schizophrenia (sz)-Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition(DSM-IV) and International Classification of Diseases, 10th Revision(ICD-10)-are widely considered as important scientific achievements. However, these algorithms were not a product of explicit conceptual analyses and empirical studies but defined through consensus with the purpose of improving reliability. The validity status of current definitions and of their predecessors remains unclear. The so-called "polydiagnostic approach" applies different definitions of a disorder to the same patient sample in order to compare these definitions on potential validity indicators. We reviewed 92 polydiagnostic sz studies published since the early 1970s. Different sz definitions show a considerable variation concerning frequency, concordance, reliability, outcome, and other validity measures. The DSM-IV and the ICD-10 show moderate reliability but both definitions appear weak in terms of concurrent validity, eg, with respect to an aggregation of a priori important features. The first-rank symptoms of Schneider are not associated with family history of sz or with prediction of poor outcome. The introduction of long duration criteria and exclusion of affective syndromes tend to restrict the diagnosis to chronic stable patients. Patients fulfilling the majority of definitions (core sz patients) do not seem to constitute a strongly valid subgroup but rather a severely ill subgroup. Paradoxically, it seems that a century after the introduction of the sz concept, research is still badly needed, concerning conceptual and construct validity of sz, its essential psychopathological features, and phenotypic boundaries.

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    • "Nithsdale survey used the ICD 9 criteria to diagnose schizophrenia, while the present study used ICD10. Therefore an important consideration to make is whether any of our findings (prevalence, change in symptoms, social functioning) could be explained as a result of the use of a different classification systems (Jansson and Parnas, 2007). A Danish cross-sectional study, of 155 consecutive 'first-admitted' patients with psychotic illnesses, to an inpatient unit, showed a striking difference in the numbers of patients diagnosed with ICD 9 schizophrenia, compared to ICD 10 (Jansson et al., 2002). "
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    ABSTRACT: BACKGROUND: Major changes in the treatment of schizophrenia have taken place in recent years, including a shift from inpatient to community care, and the introduction of second-generation antipsychotics and psychosocial interventions. Recent evidence has questioned the superiority of these interventions over older treatments. AIMS: We wished to ascertain the impact of changes in the treatment of schizophrenia in a geographically-defined area, focusing on clinical symptoms and psychosocial outcome. METHODS: In 2006, we replicated the survey carried out in 1981, identifying the population of people with schizophrenia living in Nithsdale, South-West Scotland, measuring prevalence using the 'key informant' method. We assessed their clinical and social functioning, using similar scales, and compared measures across both time periods. RESULTS: We identified 205 people with schizophrenia, a point prevalence of 3.59/1000 general population. In 2006, while fewer people experienced negative symptoms, a greater number experienced positive symptoms. There were no significant differences in the prevalence of tardive dyskinesia or Parkinsonism, though tremor was less common in the 2006 population. In 2006, there were fewer people living with a spouse/partner or parents, and fewer were in open employment in comparison to the 1981 population. The overall level of social adjustment had not changed. CONCLUSIONS: The clinical manifestation of schizophrenia appears to have changed over the last 25years, within this geographically-defined area, the prevalence of negative symptoms having decreased, and positive symptoms seem to have increased. The level of social functioning does not appear to have changed over the last 25years.
    Schizophrenia Research 03/2013; 146(1-3). DOI:10.1016/j.schres.2013.02.006 · 3.92 Impact Factor
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    • "). Diagnostic criteria for schizophrenia in DSM–IV–TR consider it as a discrete entity and separate it especially from the affective psychoses (Dutta et al., 2007). As scientific evidence mounts, however, it is doubtful whether these discrete diagnostic groups have discriminant validity (Jansson & Parnas, 2007). Polydiagnostic studies actually do show considerable variation concerning their frequency, concordance, reliability , and outcome when using different sets of diagnostic criteria (Jansson & Parnas, 2007). "
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    ABSTRACT: The aim of the study was to investigate the validity of the Rorschach Perceptual Thinking Index (PTI) to detect psychotic perceptual and thought disturbance in a sample of Slovene psychiatric inpatients. Using a sample of 275 adult psychiatric inpatients of both sexes, we examined the differences between patients with psychosis (PP) and patients with no psychotic features (NP) from various diagnostic groups on the global PTI and its subcomponent variables. PPs obtained significantly higher PTI scores, indicating more disturbed perception and more thinking disturbance, than NPs. No differences were found for diagnostic differences within the PP and NP groups. Results are in accordance with previous studies of the PTI as a valid cross-cultural index of perceptual and thinking disturbance.
    Journal of Personality Assessment 02/2013; 95(2):141-148. DOI:10.1080/00223891.2012.753898 · 1.84 Impact Factor
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    • "Second, once a drug is introduced to a clinical population, its efficacy is assessed using traditional clinical end-points, such as clinical rating scales. Their sole dependence on the patients' reports and clinician's observations introduces a subjective element that reduces their sensitivity and precision (Jansson and Parnas, 2007). In addition, these end-points account poorly for the cross-ethnic differences in psychopathology (Brekke and Barrio, 1997), which makes international comparisons difficult. "
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    ABSTRACT: Antipsychotic drugs are the mainstay of treatment for schizophrenia but they have little effect on core negative symptoms or cognitive impairment. To meet the deficiencies of current treatments, novel potential compounds are emerging from preclinical research but translation to clinical success has been poor. This article evaluates the possibility that cognitive and physiological abnormalities in schizophrenia can be used as central nervous system biomarkers to predict, in healthy volunteers, the likely efficacy of entirely new pharmacological approaches to treatment. Early detection of efficacy would focus resource on rapidly developing, effective drugs. We review the relevance of selected cognitive and physiological abnormalities as biomarkers in schizophrenia and three of its surrogate populations: (i) healthy volunteers with high trait schizotypy; (ii) unaffected relatives of patients; and (iii) healthy volunteers in a state of cortical glutamate disinhibition induced by low-dose ketamine. Several biomarkers are abnormal in these groups and in some instances there has been exploratory work to determine their sensitivity to drug action. They are generally insensitive to current antipsychotics and therefore their predictive validity cannot be established until novel, therapeutically useful drugs are discovered. Until then such biomarker studies can provide evidence of drugs engaging with the mechanism of interest and encouragement of the concept.
    Journal of Psychopharmacology 09/2011; 25(9):1207-25. DOI:10.1177/0269881111414450 · 3.59 Impact Factor
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