Social defeat: risk factor for schizophrenia? Br J Psychiatry
Utrecht University, Utrecht, Utrecht, NetherlandsThe British Journal of Psychiatry (Impact Factor: 7.99). 09/2005; 187:101-2. DOI: 10.1192/bjp.187.2.101
The hypothesis that chronic and long-term experience of 'social defeat' may increase the risk for schizophrenia is proposed. This increased risk may result from sensitisation of the mesolimbic dopamine system and/or increased baseline activity of this system. Data supporting the social defeat hypothesis are presented.
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- "Experiments in which human subjects are exposed to physical defeat would not be ethical. Besides, the subjective experience of SD is difficult to measure because individual self-assessments are sensitive to bias (Selten and Cantor-Graae, 2005). Absence of laboratory experiments in humans may also be a consequence of the difficulty in formulating an operational definition of the SD experience. "
ABSTRACT: The social defeat (SD) hypothesis of schizophrenia posits that repeated experiences of SD may lead to sensitization of the mesolimbic dopaminergic system and to precipitation of psychosis. Based on previous definitions adapted to a human experimental paradigm, we prepared a computer simulation of SD to mimic this subjective experience. We measured prefrontal cortex (PFC) activity in subjects with schizophrenia and healthy controls during exposure to a single SD experience with functional near infrared spectroscopy. PFC activity declined in both groups. Compared with the control condition, SD exposure was associated with a broader decline in left ventromedial, right medial and right lateral PFC activity in healthy controls (n=25), and a sharper decline in right ventrolateral PFC activity in subjects with schizophrenia (n=25). The activity in the right ventrolateral PFC, was significantly lower in patients compared with controls. This may be due to a deficiency in emotion regulation or self-control, or it may be related to impaired empathy in schizophrenia. Different patterns of brain activity during the SD experience in subjects with schizophrenia versus healthy controls may provide indirect evidence regarding the SD hypothesis of schizophrenia. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
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- "This model suggested that PTSD symptom clusters (avoidance, arousal, and re-experiencing) could have both direct effects on psychosis symptoms and indirect effects through traumatic sequelae such as substance abuse, re-traumatization, and interpersonal difficulties. Other models have attempted to explain these trauma–psychosis associations (Bentall & Fernyhough, 2008; Selten & Cantor-Graae, 2005). Cognitive models suggest that there may be numerous casual routes to the development and maintenance of psychotic symptoms such as adverse experiences, social marginalization, and the experience of childhood trauma (Garety, Kuipers, Fowler, Freeman, & Bebbington, 2001; Morrison, 2001; Morrison et al., 2003). "
ABSTRACT: Objective Previous research has identified an association between traumatic experiences and psychotic symptoms. Few studies, however, have explored the underlying mechanisms and contingent nature of these associations in an integrated model. This study aimed to test a moderated mediation model of negative childhood experiences, associated cognitive processes, and psychotic experiences within a context of adolescent loneliness.DesignCross-sectional survey.MethodsA total of 785 Northern Irish secondary school adolescents completed the survey. A moderated mediation model was specified and tested.ResultsChildhood experiences of threat and subordination were directly associated with psychotic experiences. Analyses indicated that peer victimization was a mediator of this effect and that loneliness moderated this mediated effect.ConclusionA new model is proposed to provide an alternative framework for assessing the association between trauma and psychotic experience in adolescence that recognizes loneliness as a significant contextual moderator that can potentially strengthen the trauma–psychosis relationship.Practitioner pointsModerated mediation analyses poses an alternative framework to the understanding of trauma–psychosis associationsAdolescent loneliness is a vulnerability factor within this associationData are based on a Northern Irish sample with relatively low levels of lonelinessCross-sectional data cannot explore the developmental course of these experiences in adolescence.
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- "Estos datos proporcionan la evidencia más convincente del papel de los factores socioeconómicos en la etiología de la esquizofrenia Selten y Cantor - Graae 57 ( 2005 ) Analizar la afectación del estrés crónico y el desarrollo social en el aumento de factores de riesgo en la esquizofrenia Revisión Se propone la hipótesis de que la experiencia social crónica puede aumentar el riesgo al desarrollo de esquizofrenia . Este aumento de riesgo puede resultar de la sensibilización del sistema mesolímbico de la dopamina y / o el aumento de la actividad basal de este sistema Cantor - Graae y Selten 58 ( 2005 ) Analizar y revisar la migración como factor de riesgo para el desarrollo de la esquizofrenia Revisión entre los a ˜ nos 1977 y 2003 El riesgo relativo de medias ponderadas para el desarrollo de la esquizofrenia entre los inmigrantes de primera generación ( 40 tamã nos del efecto ) fue de 2 , 7 ( IC 95% 2 , 3 - 3 , 2 ) . Un análisis independiente realizado por inmigrantes de segunda generación ( 7 tamã nos del efecto ) produjo un riesgo relativo de 4 , 5 ( IC 95% 1 , 5 - 13 , 1 ) . "
ABSTRACT: This paper reviews and discusses the published information on stressful life events and their influence on the onset of a first psychotic episode. The aim is to update and promote further investigation into these events in the context of a stress-vulnerability model. Milestone studies that referred to the key thematic stressful life events, such as adolescence, coping, resilience, and ethnic differences. A search was conducted using PsycINFO, MEDLINE and PSICODOC between 1980 and 2013 using the following terms: Stressful life events, adolescence, coping, resilience, schizophrenia, stress, first psychotic episode, and vulnerability. A total of 289 studies were found, of which 59 were selected for review. The integrated assessment of stressful life events, along with other individual and contextual variables, allow an approach for an early detection and a prevention tool. The results suggest the need for a multiple and integrated approach, since there are several factors that are involved in the whole network which forms a first psychotic episode.