Risk factors and confounders in the geographical clustering of schizophrenia

Torrey, E. Fuller; Mortensen, Preben Bo; Pedersen, Carsten Bøcker; Wohlfahrt, Jan; Melbye, Mads

doi:10.1016/s0920-9964(00)00081-5

Cited by 16 publications

(19 citation statements)

References 18 publications

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“…The ÆSOP study also reported higher rates of affective psychoses [1*] and bipolar disorder [100*] in Southeast London compared with Nottingham or Bristol, having adjusted for age and sex, but these effects were smaller than for their non-affective counterparts and did not persist following additional control for ethnicity. Further, when rates of affective psychoses were compared within neighborhoods [96*], there was no evidence to support spatial variation in incidence, after adjustment for age, sex and ethnicity; these findings are consistent with the remaining literature identified by our review [78], [79*], [83*] and elsewhere [125], [129], [130], [131]. We did not identify any citations which had considered spatial variation in the incidence of depressive or substance-induced psychoses.…”

Section: Resultssupporting

confidence: 78%

Incidence of Schizophrenia and Other Psychoses in England, 1950–2009: A Systematic Review and Meta-Analyses

et al. 2012

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BackgroundWe conducted a systematic review of incidence rates in England over a sixty-year period to determine the extent to which rates varied along accepted (age, sex) and less-accepted epidemiological gradients (ethnicity, migration and place of birth and upbringing, time).ObjectivesTo determine variation in incidence of several psychotic disorders as above.Data SourcesPublished and grey literature searches (MEDLINE, PSycINFO, EMBASE, CINAHL, ASSIA, HMIC), and identification of unpublished data through bibliographic searches and author communication.Study Eligibility CriteriaPublished 1950–2009; conducted wholly or partially in England; original data on incidence of non-organic adult-onset psychosis or one or more factor(s) pertaining to incidence.ParticipantsPeople, 16–64 years, with first -onset psychosis, including non-affective psychoses, schizophrenia, bipolar disorder, psychotic depression and substance-induced psychosis.Study Appraisal and Synthesis MethodsTitle, abstract and full-text review by two independent raters to identify suitable citations. Data were extracted to a standardized extraction form. Descriptive appraisals of variation in rates, including tables and forest plots, and where suitable, random-effects meta-analyses and meta-regressions to test specific hypotheses; rate heterogeneity was assessed by the I2-statistic.Results83 citations met inclusion. Pooled incidence of all psychoses (N = 9) was 31.7 per 100,000 person-years (95%CI: 24.6–40.9), 23.2 (95%CI: 18.3–29.5) for non-affective psychoses (N = 8), 15.2 (95%CI: 11.9–19.5) for schizophrenia (N = 15) and 12.4 (95%CI: 9.0–17.1) for affective psychoses (N = 7). This masked rate heterogeneity (I2: 0.54–0.97), possibly explained by socio-environmental factors; our review confirmed (via meta-regression) the typical age-sex interaction in psychosis risk, including secondary peak onset in women after 45 years. Rates of most disorders were elevated in several ethnic minority groups compared with the white (British) population. For example, for schizophrenia: black Caribbean (pooled RR: 5.6; 95%CI: 3.4–9.2; N = 5), black African (pooled RR: 4.7; 95%CI: 3.3–6.8; N = 5) and South Asian groups in England (pooled RR: 2.4; 95%CI: 1.3–4.5; N = 3). We found no evidence to support an overall change in the incidence of psychotic disorder over time, though diagnostic shifts (away from schizophrenia) were reported.LimitationsIncidence studies were predominantly cross-sectional, limiting causal inference. Heterogeneity, while evidencing important variation, suggested pooled estimates require interpretation alongside our descriptive systematic results.Conclusions and Implications of Key FindingsIncidence of psychotic disorders varied markedly by age, sex, place and migration status/ethnicity. Stable incidence over time, together with a robust socio-environmental epidemiology, provides a platform for developing prediction models for health service planning.

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Section: Resultssupporting

confidence: 78%

Incidence of Schizophrenia and Other Psychoses in England, 1950–2009: A Systematic Review and Meta-Analyses

et al. 2012

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“…However, our previous study concluded that the timing of the urban cause(s) or exposure(s) was from birth to the fifteenth birthday and that no ages during upbringing were particularly vulnerable to residence in urban areas (Pedersen & Mortensen, 2001 a). However, our previous study concluded that the timing of the urban cause(s) or exposure(s) was from birth to the fifteenth birthday and that no ages during upbringing were particularly vulnerable to residence in urban areas (Pedersen & Mortensen, 2001 a).…”

Section: Discussionmentioning

confidence: 89%

“…As the earliest age at admission with schizophrenia in Denmark is 15 (Pedersen & Mortensen, 2001 b) and the Danish Psychiatric Central Register has been assumed to contain complete case-ascertainment of all people who develop schizophrenia from 1 April 1970 onwards (e.g. First, there should be complete case-ascertainment of all people who developed schizophrenia and they should be admitted at the time of onset of schizophrenia.…”

Section: Methodsmentioning

confidence: 99%

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No evidence of time trends in the urban–rural differences in schizophrenia risk among five million people born in Denmark from 1910 to 1986

Pedersen

2005

Psychol. Med.

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“…A description of the Stanley Brain Collection and more detailed demographics and samples' quality were previously reported [60]. RNA expression analysis was conducted with the samples coded to keep investigators blind to diagnostic status.…”

Section: Methodsmentioning

confidence: 99%

Decreased Expression of Sprouty2 in the Dorsolateral Prefrontal Cortex in Schizophrenia and Bipolar Disorder: A Correlation with BDNF Expression

Pillai

2008

PLoS ONE

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BackgroundCurrent theories on the pathophysiology of schizophrenia suggest altered brain plasticity such as decreased neural proliferation and migration, delayed myelination, and abnormal synaptic modeling, in the brain of subjects with schizophrenia. Though functional alterations in BDNF, which plays important role in neuroplasticity, are implicated in many abnormalities found in schizophrenia, the regulatory mechanism(s) involved in the abnormal signaling of BDNF in schizophrenia is not clear. The present study investigated whether Sprouty2, a regulator of growth factor signaling, is abnormally expressed in schizophrenia, and is associated with the changes in BDNF mRNA in this disorder. The potential effect of antipsychotic drugs on Sprouty2 expression was tested in adult rats.Methods and FindingsSprouty2 and BDNF gene expression were analyzed in dorsolateral prefrontal cortex samples from the Stanley Array Collection. Quantitative real-time PCR analysis of RNA in 100 individuals (35 with schizophrenia, 31 with bipolar disorder, and 34 psychiatrically normal controls) showed significantly decreased expression of Sprouty2 and BDNF in both schizophrenia and bipolar disorder. Moreover, a significant correlation between these two genes existed in control, schizophrenia and bipolar subjects. Long-term treatment with antipsychotic drugs, haloperidol and olanzapine, showed differential effects on both Sprouty2 and BDNF mRNA and protein levels in the frontal cortex of rats.ConclusionThese findings demonstrating decreased expression of Sprouty2 associated with changes in BDNF, suggest the possibility that these decreases are secondary to treatment rather than to factors that are significant in the disease process of either schizophrenia and/or bipolar disorder. Further exploration of Sprouty2-related signal transduction pathways may be helpful to design novel treatment strategies for these disorders.

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Risk factors and confounders in the geographical clustering of schizophrenia

Cited by 16 publications

References 18 publications

Incidence of Schizophrenia and Other Psychoses in England, 1950–2009: A Systematic Review and Meta-Analyses

Incidence of Schizophrenia and Other Psychoses in England, 1950–2009: A Systematic Review and Meta-Analyses

No evidence of time trends in the urban–rural differences in schizophrenia risk among five million people born in Denmark from 1910 to 1986

Decreased Expression of Sprouty2 in the Dorsolateral Prefrontal Cortex in Schizophrenia and Bipolar Disorder: A Correlation with BDNF Expression

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