Positive and negative symptoms in affected sib pairs with schizophrenia: Implications for genetic studies in an African Xhosa sample

Niehaus, Dana J.H.; Koen, Liezl; Laurent, Claudine; Muller, Jacqueline E.; Deleuze, Jean‐François; Mallet, Jacques; Seller, Cathlene; Jordaan, Esmè; Emsley, Robin

doi:10.1016/j.schres.2005.04.026

Cited by 25 publications

(18 citation statements)

References 44 publications

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“…17,25 The absence of methamphetamine use/abuse in our sample, in view of the current high prevalence rates of methamphetamine use/abuse in the Western Cape, is notable. Secondly, cannabis has for generations been regarded as a traditional drug among the indigenous southern African populations, and its use has therefore possibly been associated with low moral blameworthiness.…”

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confidence: 74%

Cannabis use and abuse correlates in a homogenous South African schizophrenia population

2009

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Objective. Worldwide, cannabis is the most widely used illicit substance, and it has been identified as a correlate in schizophrenia samples for poorer symptomatic and functional outcomes in many international studies. The object of this retrospective study was to identify the prevalence of cannabis use/abuse and the demographic and clinical correlates therefor in a large homogeneous South African schizophrenia population.Methods. As part of a large genetic study, 547 subjects with a diagnosis of schizophrenia were recruited. Demographic and clinical data were collected and each participant underwent a urinary drug screen. Use/abuse of cannabis was defined as using cannabis more than 21 times in a single year. Subjects with and without cannabis use/abuse were statistically compared. Results. Significant differences between the two groups were found in terms of gender, marital status, age of onset of schizophrenia, number of hospitalisations and relapses, alcohol abuse, smoking, the Scale for the Assessment of Positive Symptoms (SAPS) scores for hallucinations, delusions, bizarre behaviour and formal thought disorder, and the Scale for the Assessment of Negative Symptoms (SANS) score for avolition/apathy. Conclusion. The prevalence of cannabis use/abuse in this study was high, and our findings were comparable with those of previous international studies. Abuse/use started mainly in the teenage years, was more prevalent among males than females, and was associated with negative overall outcomes. There was also a positive correlation between cannabis and nicotine and alcohol use/abuse. Determination of cannabis abuse based solely on history was found to be reliable, and urine cannabis testing appeared to be of limited value in routine management of this group of schizophrenic patients.

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confidence: 74%

Cannabis use and abuse correlates in a homogenous South African schizophrenia population

2009

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“…For the analyses of clinical symptoms of schizophrenia, a threefactor model containing negative, positive, and disorganization dimensions was examined using the 7 global ratings from the SANS and SAPS following previous studies [Emsley et al, 2001;Niehaus et al, 2005].…”

Section: Factor Analysismentioning

confidence: 99%

The multidimensionality of schizotypy in nonpsychotic relatives of patients with schizophrenia and its applications in ordered subsets linkage analysis of schizophrenia

Lien

Tsuang

Chiang

et al. 2009

American J of Med Genetics Pt B

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This study aimed to examine the multidimensionality of schizotypy and validate the structure using ordered subset linkage analyses on information from both relatives' schizotypy and probands' schizophrenia symptoms. A total of 203 and 1,310 nonpsychotic first-degree relatives from simplex and multiplex schizophrenia families, respectively, were interviewed with the Diagnostic Interview for Genetic Studies, which contains a modified Structured Interview for Schizotypy. Using Mplus program with categorical factor indicators, a four-factor model (Negative Schizotypy, Positive Schizotypy, Interpersonal Sensitivity, and Social Isolation/Introversion) was extracted by exploratory factor analysis from relatives of simplex families and was confirmed in relatives of multiplex families. The validity of each factor was supported by distinct linkage findings resulting from ordered subset analysis based on different combinations of schizophrenia-schizotypy factors. Six chromosomal regions with significant increase in nonparametric linkage z score (NPL-Z) were found as follows: 15q21.1 (NPL-Z = 3.60) for Negative Schizophrenia-Negative Schizotypy, 10q22.3 (NPL-Z = 3.83) and 15q21.3 (NPL-Z = 3.36) for Negative Schizophrenia-Social Isolation/Introversion, 5q14.2 (NPL-Z = 3.20) and 11q23.3 (NPL-Z = 3.31) for Positive Schizophrenia-Positive Schizotypy, and 4q32.1 (NPL-Z = 3.31) for Positive Schizophrenia-Interpersonal Sensitivity. The greatest NPL-Z of 3.83 on 10q22.3 in the subset was significantly higher than the greatest one of 2.88 in the whole sample (empirical P-value = 0.04). We concluded that a consistent four-factor model of schizotypy could be derived in nonpsychotic relatives across families of patients with different genetic loadings in schizophrenia. Their differential relations to linkage signals have etiological implications and provide further evidence for their validity.

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“…Studies of affected sibling pairs have generally found modest familial aggregation for each symptom dimension (within-pair correlations or agreement up to 0.35) [Burke et al, 1996;Hwu et al, 1997;Kendler et al, 1997;Loftus et al, 1998Loftus et al, , 2000Cardno et al, 1999a;Niehaus et al, 2005], and some studies have found that scores on the negative [Dworkin and Lenzenweger, 1984;Van Os et al, 1997;Cardno et al, 2002;Peralta and Cuesta, 2007a] In an initial study of the Maudsley twin psychosis series [Cardno et al, 2001], we found modest familial aggregation for positive dimension definitions in affected MZ pairs (correlations up to 0.2), but trends towards higher familial aggregation for some definitions of the negative and disorganized dimensions (correlations up to 0.6). Proband factor scores for the disorganized dimension predicted risk of psychosis in co-twins, and this effect was greater in MZ than DZ pairs, consistent with this dimension being a marker of genetic liability to psychosis.…”

Section: Introductionmentioning

confidence: 99%

Twin study refining psychotic symptom dimensions as phenotypes for genetic research

Cardno

Rijsdijk

Murray

et al. 2008

American J of Med Genetics Pt B

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We investigated which psychotic symptom dimensions are likely to be most useful as phenotypes for genetic linkage and association studies. Two hundred twenty-four probandwise twin pairs (106 monozygotic,118 same-sex dizygotic), where probands had psychosis, were ascertained from the Maudsley Twin Register in London. Dimensions were defined as ordinal symptom scores using the OPCRIT checklist, based on previous factor analyses of this and other samples. To qualify as a potentially useful phenotype, dimensions had to show (a) a satisfactory polychoric model fit and significant within-pair correlation in MZ pairs concordant for DSM-III-R psychosis and (b) that they could not be better defined in terms of other combinations of relevant symptoms, single symptoms, or dichotomized dimension scores. Relationships between dimension scores in twin probands and risk of psychosis in co-twins were also investigated. None of the positive or negative dimensions satisfied the phenotypic criteria. The disorganized dimensions showed significant and substantial correlations which maximized for a narrow definition. Combined negative/disorganized dimensions also showed significant and substantial correlations, but did not have advantages over disorganized dimensions. None of the dimensions were significant predictors of psychosis risk in co-twins. We conclude that, of the dimensions analyzed, the narrow disorganized dimension shows most promise as a phenotype for molecular genetic research.

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Positive and negative symptoms in affected sib pairs with schizophrenia: Implications for genetic studies in an African Xhosa sample

Cited by 25 publications

References 44 publications

Cannabis use and abuse correlates in a homogenous South African schizophrenia population

Cannabis use and abuse correlates in a homogenous South African schizophrenia population

The multidimensionality of schizotypy in nonpsychotic relatives of patients with schizophrenia and its applications in ordered subsets linkage analysis of schizophrenia

Twin study refining psychotic symptom dimensions as phenotypes for genetic research

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