Does religious belief enable positive interpretation of auditory hallucinations?: a comparison of religious voice hearers with and without psychosis.

Introduction. Hearing voices occurs in people without psychosis. Why hearing voices is such a key pathological feature of psychosis whilst remaining a manageable experience in nonpsychotic people is yet to be understood. We hypothesised that religious voice hearers would interpret voices in accordance with their beliefs and therefore experience less distress. Methods. Three voice hearing groups, which comprised: 20 mentally healthy Christians, 15 Christian patients with psychosis, and 14 nonreligious patients with psychosis. All completed (1) questionnaires with rating scales measuring the perceptual and emotional aspects of hallucinated voices, and (2) a semistructured interview to explore whether religious belief is used to make sense of the voice hearing experience. Results. The three groups had perceptually similar experiences when hearing the voices. Mentally healthy Christians appeared to assimilate the experience with their religious beliefs (schematic processing) resulting in positive interpretations. Christian patients tended not to assimilate the experience with their religious beliefs, frequently reporting nonreligious interpretations that were predominantly negative. Nearly all participants experienced voices as powerful, but mentally healthy Christians reported the power of voices positively. Conclusion. Religious belief appeared to have a profound, beneficial influence on the mentally healthy Christians' interpretation of hearing voices, but had little or no influence in the case of Christian patients.

Is semantic memory impaired in schizophrenia? A systematic review and meta-analysis of 91 studies.

INTRODUCTION: Semantic memory impairments in schizophrenia have been reported across a wide range of neuropsychological tests. Set against a backdrop of fairly widespread cognitive impairments, it is difficult to know whether there is a primary, or secondary, impairment of semantic memory in schizophrenia. Also, whether there is a profile of differential impairment across the range of neuropsychological tests. METHODS: Employing a systematic search strategy, 91 papers were identified which have assessed participants with schizophrenia on a measure of semantic memory. A series of meta-analyses were then conducted which provided combined weighted means for performance on tasks of naming, word-picture matching, verbal fluency, priming, and categorisation. RESULTS: An uneven profile of impairment is reported with large effect sizes for tests of naming and verbal fluency, medium effect sizes for word-picture matching and association and small effect sizes for categorisation and priming tests. CONCLUSIONS: This uneven profile supports the claim that a degradation of semantic knowledge may not be adequate in explaining the semantic memory impairment in schizophrenia. This conclusion is supported by the data which report a relationship between an executive dysfunction and poor priming and fluency performance particularly. The data support a link between Formal Thought Disorder and semantic memory impairments on tests of naming and verbal fluency but on other tests evidence is equivocal.

Semantic memory impairment in schizophrenia--deficit in storage or access of knowledge?

This study evaluates whether patients with schizophrenia have a degraded memory store for semantic knowledge. 20 patients with a chronic history of schizophrenia and evidence of cognitive impairment were selected, since the literature indicates that this subgroup is most likely to manifest a degraded semantic knowledge store. Their profile of semantic memory impairments was compared to that of a group of Alzheimer's Dementia (AD) patients (n=22), who met neuropsychological criteria for degraded semantic store. Both groups were matched for Performance IQ. 15 elderly healthy controls were also included in the study. The AD and schizophrenia groups produced substantially different profiles of semantic memory impairment. This is interpreted as indicating that the semantic impairments in this subgroup of patients with schizophrenia do not result from a degraded store. This is corroborated by an analysis of the data using other neuropsychological criteria for determining degraded store. We conclude that there is little evidence for a classic degradation of semantic knowledge in schizophrenia, and it appears that impairments result from an inability to use semantic knowledge appropriately, particularly when selection of salient semantic relations is required.

Do overinclusion and distorted semantic category boundaries in schizophrenia arise from executive dysfunction?

Semantic memory impairments have been reported extensively in people with schizophrenia. Inefficient search and retrieval strategies, due to an executive dysfunction, rather than a primary loss of semantic knowledge are a primary candidate for such impairments. In order to test this hypothesis we compared the performance of 20 patients meeting DSM-IV-TR criteria for schizophrenia with that of 20 healthy controls and 10 patients with acquired brain injury (ABI) with a dysexecutive syndrome. Seventy percent of the people with schizophrenia and 100% of the ABI patients in this study met criteria for executive impairment. However, the two groups performed significantly differently on a range of semantic memory tests. Whereas 45% of the patients with schizophrenia met criteria for distorted semantic category boundaries (n.b. overinclusion), this was true for only 10% of the ABI patients. In addition, no correlation was found between severity of executive dysfunction and tendency to overinclude in the schizophrenia group. This pattern of neuropsychological findings suggests that overinclusion, or disorganized semantic categorization procedures, in schizophrenia does not result from a classical executive dysfunction. Alternative explanations are discussed.