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Quantfying the disorganization and the core deficit in classical schizophrenia
- Mohan Rathnaiah, Elizabeth B Liddle, Lauren Gascoyne, Jyothika Kumar, Mohammad Zia Ul-Haq Katshu, Catherine Faruqui, Christina Kelly, Malkeet Gill, Sian Robson, Peter Morris, Mathew Brookes, Peter Liddle
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- Journal:
- BJPsych Open / Volume 7 / Issue S1 / June 2021
- Published online by Cambridge University Press:
- 18 June 2021, p. S283
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Aims
To derive scores for mental disorganization and impoverishment from commonly used rating scales, and test the hypothesis that disorganization and impoverishment, along with impaired cognition and role-function reflect a latent variable that is a plausible candidate for the putative core deficit.
BackgroundFor more than 100 years, disorganization and impoverishment of mental activity have been recognised as fundamental symptoms of schizophrenia. These symptoms may reflect a core brain process underlying persisting disability. Delusions and hallucinations have been regarded as accessory features. The psychopathological processes predisposing to persisting disability in schizophrenia are poorly understood. The delineation of a core deficit underlying persisting disability would be potentially of great value in predicting outcome and developing improved treatment.
MethodPatients aged 18–55 years were included if: they satisfied DSM IV criteria for schizophrenia or schizoaffective disorder. Healthy controls were recruited by public advertisement and selected to match the patient group in age and sex. Study sample included 39 participants with schizophrenia, 1 with schizoaffective disorder and 44 matched healthy controls. We derived disorganization and impoverishment scores from three symptom scales: PANSS, SSPI and CASH. We computed composite scores for disorganization and for impoverishment and employed Confirmatory Factor Analysis to test the hypothesis that a single factor accounts for the relationships between disorganization, impoverishment, cognitive impairment and impaired role function. We assessed the relationship between this latent “core deficit” and diminished Post Movement Beta Rebound (PMBR), an electrophysiological measure from Magnetoencephalography (MEG), associated with persisting brain disorders.
ResultFit indices for the single factor model from CFA indicated a good fit: χ2(2) = 1.817, p = .403; RMSEA <.001 GFI = .979. PMBR was significantly reduced in the schizophrenia group compared to healthy controls, t (68) = 3.55, p < .001. Within the patient group, PMBR was significantly and negatively correlated with the CFA factor scores representing the Core Deficit score, r=−.543, p < .01, indicating that high core deficit scores were associated with reduced PMBR. PMBR was significantly correlated with the composite Disorganization score, r=−.521, p < .001.
ConclusionOur findings demonstrate that the shared variance between impoverishment (psychomotor poverty); disorganization; cognitive impairment; and impaired role function can be accounted for by a latent variable that can reasonably be described as the core deficit of classical schizophrenia. The demonstration that the severity of the putative core deficit is correlated with the reduction in PMBR provides evidence that the core deficit is associated with an identifiable abnormality of brain dysfunction.
Monitoring vegetation change in desert oases by remote sensing; a case study in the Libyan Fazzān
- Kevin White, Nick Brooks, Nick Drake, Mathew Charlton, Sue MacLaren
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- Journal:
- Libyan Studies / Volume 34 / 2003
- Published online by Cambridge University Press:
- 03 March 2015, pp. 153-166
- Print publication:
- 2003
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Desert oases are undergoing rapid changes in response to environmental, economic and social pressures. The Wādī al-Hayāt, in the Libyan Fazzān, illustrates these changes and exemplifies some of the processes at work. Human activity in the area is dependent on groundwater extraction. Introduction of mechanical pumps and modern irrigation technology has enabled significant expansion of irrigated area, but environmental problems have arisen as a result. Geoarchaeological studies have demonstrated that groundwater levels have fallen over the latter half of the Holocene. Large decreases have occurred since 1970 as a result of abstraction for agricultural, domestic and industrial use. This study uses aerial photographs from 1958 and Landsat imagery from 1987, 1999 and 2000 to map changes in the area under irrigation in the Wādī al-Hayāt. We find a general southwards migration of oasis agriculture within the Wādī, as vegetation has died in the northern part of the Wādī and irrigation extended to the south. A significant amount of inter-annual change in vegetation cover is identified, indicating the need to account for seasonal cropping practices when monitoring for longer-term changes.