Can the new epidemiology of schizophrenia help elucidate its causation?

Abstract

The supposed universality of the incidence and prevalence of schizophrenia has been seriously challenged. It is now widely accepted that the life-time prevalence and incidence of this disorder vary considerably in time and place. As a result, there has been renewed interest in environmental causation of schizophrenia. There are few extant formulations that have successfully integrated the available new evidence into a coherent theory for its causation. The outgroup intolerance hypothesis is an attempt to integrate this evidence. It proposes that schizophrenia is the result of a mismatch between the social brain as shaped by evolution and the new social conditions of the post-neolithic. The hypothesis can provide an explanation for (i) the higher risk to migrants, (ii) the ethnic density phenomenon, (iii) the increased risk to individuals who have grown up in cities and (iv) the putative low risk in hunter-gatherer societies. Evidence is presented from a range of disciplines and sources including epidemiology, psychopathology, social psychology and clinical trials in support of this hypothesis. A range of testable predictions follow from the hypothesis.

A Comprehensive Review of Computational Methods for Automatic Prediction of Schizophrenia With Insight Into Indigenous Populations

“…Schizophrenia is found worldwide in diverse cultures. Within a Western model of schizophrenia, this condition has been purported to be fundamentally similar across all cultures with the only difference in its content and form (33). However, this supposed universality of the incidence and prevalence of schizophrenia has been challenged (33).…”

“…Within a Western model of schizophrenia, this condition has been purported to be fundamentally similar across all cultures with the only difference in its content and form (33). However, this supposed universality of the incidence and prevalence of schizophrenia has been challenged (33). The lifetime prevalence and incidence of this disorder varies significantly in time and place (33).…”

“…However, this supposed universality of the incidence and prevalence of schizophrenia has been challenged (33). The lifetime prevalence and incidence of this disorder varies significantly in time and place (33).…”

Letter to the Editor: Oxytocin and empathy to pain in schizophrenia

“…Although OT failed to ‘normalize’ the response towards out-group individuals (especially the conflictual out-group) we have suggested that such a normalization may be feasible if patients were treated with OT at an early stage of their illness before the neuropathological changes have reached an advanced stage (Abed & Abbas, 2014). We hypothesized that treating the illness (with OT) at an early stage or treating ‘ultra-high-risk’ patients in the prodromal phase may offer a preventative strategy through ‘resetting the threshold’ for designating others within the social environment as in-group, thus rectifying what we consider to be the core psychopathological process that leads to the fully fledged syndrome of schizophrenia.…”

“…We have proposed that in-group–out-group dynamics have aetiological significance in schizophrenia. We hypothesized that a sensitivity or intolerance towards out-group members resulting from an interaction between social environmental factors (abundance of out-group members in the social environment or paucity of contact with kin/in-group members or a combination of both) and individual characteristics (difficulty in re-assigning out-group individuals as in-group members or having a high threshold for designating individuals as in-group) results in dysregulation and aberrant connectivity in critical brain centres, leading to schizophrenia (Abed & Abbas, 2011, 2014).…”