Familiality of symptom dimensions in schizophrenia. Schizophr Res

Department of Psychological Medicine, Institute of Psychiatry, De Crespigny Park, Denmark Hill, London SE5 8A, UK.
Schizophrenia Research (Impact Factor: 3.92). 04/2001; 47(2-3):223-32. DOI: 10.1016/S0920-9964(00)00098-0
Source: PubMed


The division of schizophrenic symptoms into three core dimensions - psychomotor poverty, reality distortion, and disorganisation - is well established. When factor analytic studies have included affective symptoms they have identified two additional dimensions - manic and depressive. Whether these five dimensions represent underlying psychopathology of a genetic or environmental aetiology remains unclear. The aims of this study were to perform factor analysis of symptoms in a group of familial schizophrenic patients and to investigate the familiality of the symptom dimensions identified, and their relationship to clinical characteristics. Symptoms were recorded, using the Operational Criteria Checklist for Psychotic Illness, for 155 Caucasian subjects with an RDC diagnosis of schizophrenia, schizoaffective disorder, or psychosis of unknown origin, from 61 families multiply affected with schizophrenia. Factor analysis indicated five symptom dimensions: depressive, manic, reality distortion, disorganisation, and psychomotor poverty. The psychomotor poverty, disorganisation, and manic dimensions were shown to be familial. Psychomotor poverty, disorganisation, and reality distortion were all associated with deterioration from premorbid functioning and chronic course of the disorder. In addition, psychomotor poverty was significantly related to poor premorbid functioning, as well as to single marital status and unemployment at onset. Disorganisation was significantly related to single marital status and unemployment at onset. The familiality of the psychomotor poverty, disorganisation, and manic dimensions supports their use in the delineation of homogeneous subsets for genetic studies.

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    • "Importantly, perceptual organization impairments are observed in schizophrenia independent of medication effects (Silverstein and Keane, 2011), and can be revealed as superior performance to control groups in specificpsychophysical paradigms where prepotent grouping of targets and distractors interferes with the performance of healthy subjects (Knight and Silverstein, 2001; Place and Gilmore, 1980). Perceptual organization impairments in schizophrenia are consistently observed and associated with poor premorbid functioning, treatment response, and functional outcomes (Silverstein et al., 1998, 2000; Uhlhaas and Silverstein, 2005), suggesting that they may represent a severe illness subtype biomarker for schizophrenia (Farmer et al., 1983; Sham et al., 1996; Wickham et al., 2001). "
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    ABSTRACT: The power of SNP association studies to detect valid relationships with clinical phenotypes in schizophrenia is largely limited by the number of SNPs selected and non-specificity of phenotypes. To address this, we first assessed performance on two visual perceptual organization tasks designed to avoid many generalized deficit confounds, Kanizsa shape perception and contour integration, in a schizophrenia patient sample. Then, to reduce the total number of candidate SNPs analyzed in association with perceptual organization phenotypes, we employed a two-stage strategy: first a priori SNPs from three candidate genes were selected (GAD1, NRG1 and DTNBP1); then a Hierarchical Classes Analysis (HICLAS) was performed to reduce the total number of SNPs, based on statistically related SNP clusters. HICLAS reduced the total number of candidate SNPs for subsequent phenotype association analyses from 6 to 3. MANCOVAs indicated that rs10503929 and rs1978340 were associated with the Kanizsa shape perception filling in metric but not the global shape detection metric. rs10503929 was also associated with altered contour integration performance. SNPs not selected by the HICLAS model were unrelated to perceptual phenotype indices. While the contribution of candidate SNPs to perceptual impairments requires further clarification, this study reports the first application of HICLAS as a hypothesis-independent mathematical method for SNP data reduction. HICLAS may be useful for future larger scale genotype-phenotype association studies.
    Schizophrenia Research: Cognition 04/2015; 8(2). DOI:10.1016/j.scog.2015.03.003
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    • "Previous studies have shown that people with schizophrenia are less able to detect and make shape judgments about integrated contours when compared to various healthy and psychiatric control groups (Uhlhaas and Silverstein, 2005; Silverstein and Keane, 2011). Poor performance on CI tasks, as with other forms of perceptual organization impairment in schizophrenia (Silverstein and Keane, 2011), has also been associated with poorer premorbid social functioning (Schenkel et al., 2005; Joseph et al., 2013), elevated disorganized symptoms (Silverstein et al., 2000; Uhlhaas et al., 2005, 2006a,b), and a more chronic course of illness (Silverstein et al., 2006a) — a triad of characteristics which have been demonstrated to significantly covary and which may represent a particularly severe form of the condition (Farmer et al., 1983; Sham et al., 1996; Wickham et al., 2001). An unanswered question in the perceptual organization and CI literatures in schizophrenia is the extent to which these impairments are state-or trait-related. "
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    ABSTRACT: Contour integration is a fundamental visual process that recovers object structure by representing spatially separated edge elements as a continuous contour or shape boundary. Clinically stable persons with schizophrenia have repeatedly been shown to be impaired at contour integration but it is unclear whether this process varies with clinical state or whether it arises as early as the first episode of psychosis. To consider these issues, we administered a contour integration test to persons with chronic schizophrenia and to those with a first episode of psychosis. The test was administered twice-once at admission to short term psychiatric hospitalization and once again at discharge. A well-matched healthy control group was also tested across the same time points. We found that contour integration performance improved to the same degree in all groups over time, indicating that there were no recovery effects over and above normal practice effects. Moreover, the schizophrenia group demonstrated poorer contour integration than the control group and the first episode group exhibited intermediate performance that could not be distinguished from the other groups. These results suggest that contour integration ability does not vary as a function of short-term changes in clinical state, and that it may become further impaired with an increased number of psychotic episodes.
    Schizophrenia Research 10/2014; 159(2-3). DOI:10.1016/j.schres.2014.09.028 · 3.92 Impact Factor
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    • "Disorganization is highly heritable and linked to many of the same features as is PO impairment, including impaired attention, poor premorbid social adjustment, and poor long-term functional outcome. Many of these features typically correlate and represent a 'poor outcome' or 'process' subtype of schizophrenia (Farmer et al., 1983; Sham et al., 1996; Wickham et al., 2001). One interpretation of the above evidence is that impaired PO is an aspect of schizophrenia or subtype thereof. "
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    ABSTRACT: A subgroup of people with schizophrenia is characterized by reduced organization in perception, thought, language, and motor functioning, and these impairments covary significantly. While this may reflect multiple expressions of an illness-related core processing impairment, it may also represent the extreme end of an organization-disorganization dimension that is found throughout the general population. In this view, disorganization is a modifying influence on illness expression. To obtain preliminary information on this hypothesis, we examined covariation of perceptual and cognitive organization in a non-patient sample. Subjects completed a battery of perceptual tasks with demonstrated sensitivity to schizophrenia and disorganization, and a battery of questionnaires examining cognitive organization. Our results indicated that level of perceptual organization ability, across multiple tasks, was associated with self-reported levels of cognitive organization on multiple measures. This is thus preliminary evidence for a common process affecting perceptual and cognitive organization in the general population, suggesting that disorganization may reflect a modifying influence mechanism, instead of an illness-related process, in schizophrenia.
    03/2014; 217(1-2). DOI:10.1016/j.psychres.2014.03.005
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