Psychotic symptoms in the general population - An evolutionary perspective

The British journal of psychiatry: the journal of mental science (Impact Factor: 7.99). 09/2010; 197(3):167-9. DOI: 10.1192/bjp.bp.109.076018
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Our ideas about the intrinsically pathological nature of hallucinations and delusions are being challenged by findings from epidemiology, neuroimaging and clinical research. Population-based studies using both self-report and interview surveys show that the prevalence of psychotic symptoms is far greater than had been previously considered, prompting us to re-evaluate these psychotic symptoms and their meaning in an evolutionary context. This non-clinical phenotype may hold the key to understanding the persistence of psychosis in the population. From a neuroscientific point of view, detailed investigation of the non-clinical psychosis phenotype should provide novel leads for research into the aetiology, nosology and treatment of psychosis.

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Available from: Ian Kelleher, Apr 11, 2014

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Article: Psychotic symptoms in the general population - An evolutionary perspective

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    • "Schizophrenia may be considered a human-specific disorder arisen as a maladaptive by-product of human-specific brain evolution (Crow, 1997; Crespi et al., 2007; Kelleher et al., 2010). Therefore, assuming schizophrenia as a neurodevelopmental disorder (Rapoport et al., 2012), new schizophrenia susceptibility variants may be detected by the analysis of neurodevelopmental genes related to human-specific traits. "
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    ABSTRACT: Schizophrenia may be considered a human-specific disorder arisen as a maladaptive by-product of human-specific brain evolution. Therefore, genetic variants involved in susceptibility to schizophrenia may be identified among those genes related to acquisition of human-specific traits. NPAS3, a transcription factor involved in central nervous system development and neurogenesis, seems to be implicated in the evolution of human brain, as it is the human gene with most human-specific accelerated elements (HAEs), i.e., .mammalian conserved regulatory sequences with accelerated evolution in the lineage leading to humans after human-chimpanzee split. We hypothesize that any nucleotide variant at the NPAS3 HAEs may lead to altered susceptibility to schizophrenia. Twenty-one variants at these HAEs detected by the 1000 genomes Project, as well as five additional variants taken from psychiatric genome-wide association studies, were genotyped in 538 schizophrenic patients and 539 controls from Galicia. Analyses at the haplotype level or based on the cumulative role of the variants assuming different susceptibility models did not find any significant association in spite of enough power under several plausible scenarios regarding direction of effect and the specific role of rare and common variants. These results suggest that, contrary to our hypothesis, the special evolution of the NPAS3 HAEs in Homo relaxed the strong constraint on sequence that characterized these regions during mammalian evolution, allowing some sequence changes without any effect on schizophrenia risk. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.
    American Journal of Medical Genetics Part B Neuropsychiatric Genetics 05/2015; 168(7). DOI:10.1002/ajmg.b.32324 · 3.42 Impact Factor
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    • "These young people have been shown to share a wide range of risk factors with schizophrenia patients [34] and longitudinal research has demonstrated an increased risk of psychotic disorder in adulthood [35,36]. For these reasons, this population has been considered to represent an ‘extended psychosis phenotype’ [37] and researchers have advocated studying aetiological and risk factors for psychosis in this wider phenotype [38,39] including underlying genetic and biological factors [40], as opposed to the ‘narrow’ clinical phenotype of schizophrenia. This approach allows investigation of the earliest risk factors associated with psychosis while excluding potential confounds such as disease chronicity, medication effects and other illness related factors. "
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    ABSTRACT: Background Deficits in the mismatch negativity (MMN) and P3a components are the most reliable and robust findings in schizophrenia. These abnormalities have also been recently documented in individuals clinically at risk for psychosis, indicating that the MMN may be a potential biomarker for psychosis. However, the at risk samples included in MMN studies are characterised by pre-existing clinical symptomatology and significant functional decline which are related to MMN amplitude. These factors may be potential confounds in determining whether deficient MMN is present prior to clinical manifestation of the disorder. Therefore, investigating the MMN in the extended psychosis phenotype comprising adolescents with psychotic symptoms from the general population may provide important information on whether abnormal MMN is apparent in the earliest stages of risk. Methods Thirty six adolescents completed a duration deviant MMN task. Fourteen adolescents with psychotic symptoms comprised the at risk group and 22 with no psychotic symptoms comprised the Controls. The task consisted of 85% standard tones (25 ms) and 15% deviant tones (50 ms). The groups were compared on MMN and P3a amplitude and latency across frontocentral and temporal electrodes. Results Adolescents with psychotic symptoms were characterised by a reduction in MMN amplitude at frontal and temporal regions compared to the controls. Conclusions This is the first study to demonstrate impaired auditory discrimination for duration deviant tones in nonclinical adolescents with psychotic symptoms. These findings suggest that MMN amplitude may be a possible biomarker for vulnerability to psychosis.
    BMC Psychiatry 02/2013; 13(1):45. DOI:10.1186/1471-244X-13-45 · 2.21 Impact Factor
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    • "The prevalence of psychotic symptoms in the general population greatly exceeds the prevalence of psychotic disorders. In the absence of illness, these symptoms are also sometimes referred to as psychotic experiences or psychotic-like experiences (PLEs) (Kelleher et al., 2010). "
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    ABSTRACT: Psychotic symptoms occur more frequently in the general population than psychotic disorder and index risk for psychopathology. Multiple studies have reported on the prevalence of these symptoms using self-report questionnaires or clinical interviews but there is a lack of consensus about the prevalence of psychotic symptoms among children and adolescents. We conducted a systematic review of all published literature on psychotic symptom prevalence in two age groups, children aged 9-12 years and adolescents aged 13-18 years, searching through electronic databases PubMed, Ovid Medline, PsycINFO and EMBASE up to June 2011, and extracted prevalence rates. We identified 19 population studies that reported on psychotic symptom prevalence among children and adolescents. The median prevalence of psychotic symptoms was 17% among children aged 9-12 years and 7.5% among adolescents aged 13-18 years. Psychotic symptoms are relatively common in young people, especially in childhood. Prevalence is higher in younger (9-12 years) compared to older (13-18 years) children.
    Psychological Medicine 01/2012; 42(9):1857-63. DOI:10.1017/S0033291711002960 · 5.94 Impact Factor
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