Extended psychosis phenotype - Yes: Single continuum - Unlikely

Maastricht University Medical Centre, South Limburg Mental Health Research and Teaching Network, EURON, Maastricht, The Netherlands.
Psychological Medicine (Impact Factor: 5.94). 03/2010; 40(12):1963-6. DOI: 10.1017/S0033291710000358
Source: PubMed
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    • "We have previously reported that shared genetic factors account for the associations between childhood communication problems and adolescent psychotic experiences [Cederl€ of et al., 2014]. These findings indicate that several inter-correlated childhood neuropsychiatric problems share genetic etiological factors with the extended psychosis phenotype [Kaymaz & van Os, 2010]. In other words, the same set of genes seems to be involved in the pathogenesis of a range of neuropsychiatric symptoms in childhood as well as in vulnerability to psychosis during adolescence. "
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    ABSTRACT: Studies suggest associations between childhood autistic traits and adolescent psychotic experiences. However, recent research suggests that a general neuropsychiatric problems factor predicts adverse outcomes better than specific diagnostic entities. To examine if the alleged association between autistic traits and psychotic experiences could rather be explained by a general neuropsychiatric problems factor comprising symptoms of ADHD, tic disorder, developmental coordination disorder, and learning disorder, we conducted a prospective cohort study based on the Child and Adolescent Twin Study in Sweden. In addition, we examined the genetic and environmental influences on the associations. A total of 9,282 twins with data on childhood autistic traits and other neuropsychiatric problems, and follow-up data on psychotic experiences at ages 15 and/or 18 years were included. First, psychotic experiences were regressed on autistic traits and second, the general neuropsychiatric problems factor was added to the model. Auditory hallucinations were analyzed separately from the other psychotic experiences. Finally, twin analyses were employed to disentangle genetic from environmental influences in the observed associations. Replicating prior research, significant associations were found between autistic traits in childhood and auditory hallucinations at ages 15 and 18. However, after controlling for the general neuropsychiatric problems factor, the associations between autistic traits and auditory hallucinations disappeared, whereas the association between the general neuropsychiatric problems factor and auditory hallucinations persisted after controlling for autistic traits. Twin analyses revealed that the association between the general neuropsychiatric problems factor and auditory hallucinations was driven by shared genetic influences.
    American Journal of Medical Genetics Part B Neuropsychiatric Genetics 10/2015; 9999:1-7. DOI:10.1002/ajmg.b.32386 · 3.42 Impact Factor
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    • "Evidence supports the presence of an extended pheno - type for psychosis existing across several dimensions , including an affective domain ( David , 2010 ; Kaymaz & van Os , 2010 ) . Further examination of the ex - tent to which specific characteristics distinguish PEs from other psychopathologies could lead to a greater understanding of the aetiology of psychosis . "
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    ABSTRACT: Background: An argument often used to support the view that psychotic experiences (PEs) in general population samples are a valid phenotype for studying the aetiology of schizophrenia is that risk factors for schizophrenia show similar patterns of association with PEs. However, PEs often co-occur with depression, and no study has explicitly tested whether risk factors for schizophrenia are shared between PEs and depression, or are psychopathology specific, while jointly modelling both outcomes. Method: We used data from 7030 subjects from a birth cohort study. Depression and PEs at age 18 years were assessed using self-report questionnaires and semi-structured interviews. We compared the extent to which risk factors for schizophrenia across sociodemographic, familial, neurodevelopmental, stress-adversity, emotional-behavioural and substance use domains showed different associations with PEs and depression within bivariate models that allowed for their correlation. Results: Most of the exposures examined were associated, to a similar degree, with an increased risk of both outcomes. However, whereas female sex and family history of depression showed some discrimination as potential risk factors for depression and PEs, with stronger associations in the former, markers of abnormal neurodevelopment showed stronger associations with PEs. Conclusions: The argument that PEs are valid markers for studying the aetiology of schizophrenia, made simply on the basis that they share risk factors in common, is not well supported. PEs seem to be a weak index of genetic and environmental risk for schizophrenia; however, studies disentangling aetiological pathways to PEs from those impacting upon co-morbid psychopathology might provide important insights into the aetiology of psychotic disorders.
    Psychological Medicine 09/2014; 44(12):2557-2566. DOI:10.1017/S0033291714000026 · 5.94 Impact Factor
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    • "There is emerging evidence that a latent categorical structure of the population underlies the observed continuum of psychosis experience,2 with 1 group who are liable to psychosis and another group who are not. In the former, AVH are associated with other cognitive and emotional difficulties and a greater likelihood of need for care, while in the second group, AVH have reduced morbidity and possibly different etiology.18 This could partly explain why 2 people with the same level of AVH may differ in their clinical outcome. "
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    ABSTRACT: Auditory verbal hallucinations (AVH) are complex experiences that occur in the context of various clinical disorders. AVH also occur in individuals from the general population who have no identifiable psychiatric or neurological diagnoses. This article reviews research on AVH in nonclinical individuals and provides a cross-disciplinary view of the clinical relevance of these experiences in defining the risk of mental illness and need for care. Prevalence rates of AVH vary according to measurement tool and indicate a continuum of experience in the general population. Cross-sectional comparisons of individuals with AVH with and without need for care reveal similarities in phenomenology and some underlying mechanisms but also highlight key differences in emotional valence of AVH, appraisals, and behavioral response. Longitudinal studies suggest that AVH are an antecedent of clinical disorders when combined with negative emotional states, specific cognitive difficulties and poor coping, plus family history of psychosis, and environmental exposures such as childhood adversity. However, their predictive value for specific psychiatric disorders is not entirely clear. The theoretical and clinical implications of the reviewed findings are discussed, together with directions for future research.
    Schizophrenia Bulletin 06/2014; 40(Suppl 4):S255-S264. DOI:10.1093/schbul/sbu005 · 8.45 Impact Factor
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