Schizophrenia and the city: A review of literature and prospective study of psychosis and urbanicity in Ireland

Is there a link between air pollution and mental disorders?

Several studies have demonstrated the association between air pollution and different medical conditions including respiratory and cardiovascular diseases. Air pollutants might have a role also in the etiology of mental disorders in the light of their toxicity on central nervous system. Purpose of the present manuscript was to review and summarize available data about an association between psychiatric disorders and air pollution. A research in the main database sources has been conducted to identify relevant papers about the topic. Different air pollutants and in particular PM and nitric oxides have been associated with poor mental health; long exposition to PM_2.5 has been associated with an increased risk of new onset of depressive symptoms (Cohen's effect size d: 0.05-0.81), while increased concentration of nitric dioxide in summer with worsening of existing depressive conditions (Cohen's effect size d: 0.05-1.77). However, the interpretation of these finding should take into account the retrospective design of most of studies, different periods of observations, confounding factors such as advanced age or medical comorbidity. Further studies with rigorous methodology are needed to confirm the results of available literature about this topic.

Sensorimotor gating deficits in "two-hit" models of schizophrenia risk factors

Genetic and environmental models of neuropsychiatric disease have grown exponentially over the last 20years. One measure that is often used to evaluate the translational relevance of these models to human neuropsychiatric disease is prepulse inhibition of startle (PPI), an operational measure of sensorimotor gating. Deficient PPI characterizes several neuropsychiatric disorders but has been most extensively studied in schizophrenia. It has become a useful tool in translational neuropharmacological and molecular genetics studies because it can be measured across species using almost the same experimental parameters. Although initial studies of PPI in rodents were pharmacological because of the robust predictive validity of PPI for antipsychotic efficacy, more recently, PPI has become standard common behavioral measures used in genetic and neurodevelopmental models of schizophrenia. Here we review "two hit" models of schizophrenia and discuss the utility of PPI as a tool in phenotyping these models of relevant risk factors. In the review, we consider approaches to rodent models of genetic and neurodevelopmental risk factors and selectively review "two hit" models of gene×environment and environment×environment interactions in which PPI has been measured.

Associations between occupational stress and demographic characteristics in petroleum workers in the Xinjiang arid desert

Owing to the transformation of the biomedical model of health, more and more professionals pay close attention to the occupational social psychological factors, such as occupational stress. Due to the socioeconomic impact of occupational stress and the petroleum workers stationed in the unique environment in Xinjiang, a cross-sectional study was carried out between May and December 2016 to investigate the relationship between occupational stress and demographic characteristics. A total of 1480 workers were selected. Occupational stress was evaluated with the Occupational Stress Inventory-Revised Edition. The findings of the present study revealed that the values of the Occupational Roles Questionnaire results (t = 9.266, P < .001) and Personal Strain Questionnaire results (t = 21.381, P < .001) were found to be higher than the national normal. Personal Resources Questionnaire values (t = -17.575, P < .001) were found to be lower than the national normal in petroleum workers stationed in the arid desert, and suggested a strong correlation between occupational stress and demographic characteristics. These data provide evidence that different demographic characteristics are associated with different occupational stress levels in petroleum workers stationed in the arid desert.

Criminal victimization and psychotic experiences: cross-sectional associations in 35 low- and middle-income countries

OBJECTIVE

Criminal victimization has been associated with elevated risk for psychotic symptoms in the United Kingdom, but has not been studied in low- and middle-income countries (LMICs). Understanding whether crime exposure may play a role in the social etiology of psychosis could help guide prevention and intervention efforts.

METHOD

We tested the hypothesis that criminal victimization would be associated with elevated odds of psychotic experiences in 35 LMICs (N = 146 999) using cross-sectional data from the World Health Organization World Health Survey. Multivariable logistic regression analyses were used to test for associations between criminal victimization and psychotic experiences.

RESULTS

Victimization was associated with greater odds of psychotic experiences, OR (95% CI) = 1.72 (1.50-1.98), and was significantly more strongly associated with psychotic experiences in non-urban, OR (95% CI) = 1.93 (1.60-2.33), compared to urban settings, OR (95% CI) = 1.48 (1.21-1.81). The association between victimization and psychosis did not change across countries with varying aggregated levels of criminal victimization.

CONCLUSIONS

In the largest ever study of victimization and psychosis, the association between criminal victimization and psychosis appears to generalize across a range of LMICs and, therefore, across nations with a broad range of crime rates, degree of urban development, average per capita income, and racial/ethnic make-up.

Association of Urbanicity With Psychosis in Low- and Middle-Income Countries

Importance

Urban residence is one of the most well-established risk factors for psychotic disorder, but most evidence comes from a small group of high-income countries.

Objective

To determine whether urban living is associated with greater odds for psychosis in low- and middle-income countries (LMICs).

Design, Setting, and Participants

This international population-based study used cross-sectional survey data collected as part of the World Health Organization (WHO) World Health Survey from May 2, 2002, through December 31, 2004. Participants included nationally representative general population probability samples of adults (≥18 years) residing in 42 LMICs (N = 215 682). Data were analyzed from November 20 through December 5, 2017.

Exposures

Urban vs nonurban residence, determined by the WHO based on national data.

Main Outcomes and Measures

Psychotic experiences, assessed using the WHO Composite International Diagnostic Interview psychosis screen, and self-reported lifetime history of a diagnosis of a psychotic disorder.

Results

Among the 215 682 participants (50.8% women and 49.2% men; mean [SD] age, 37.9 [15.7] years), urban residence was not associated with psychotic experiences (odds ratio [OR], 0.99; 95% CI, 0.89-1.11) or psychotic disorder (OR, 0.89; 95% CI, 0.76-1.06). Results of all pooled analyses and meta-analyses of within-country effects approached a null effect, with an overall OR of 0.97 (95% CI, 0.87-1.07), OR for low-income countries of 0.98 (95% CI, 0.82-1.15), and OR for middle-income countries of 0.96 (95% CI, 0.84-1.09) for psychotic experiences and an overall OR of 0.92 (95% CI, 0.73-1.16), OR for low-income countries of 0.92 (95% CI, 0.66-1.27), and OR for middle-income countries of 0.92 (95% CI, 0.67-1.27) for psychotic disorder.

Conclusions and Relevance

Our results provide evidence that urbanicity, a well-established risk factor for psychosis, may not be associated with elevated odds for psychosis in developing countries. This finding may provide better understanding of the mechanisms by which urban living may contribute to psychosis risk in high-income countries, because urban-rural patterns of cannabis use, racial discrimination, and socioeconomic disparities may vary between developing and developed nations.

Acupuncture as Add-On Treatment of the Positive, Negative, and Cognitive Symptoms of Patients with Schizophrenia: A Systematic Review

Background: Schizophrenia is a severe psychiatric disorder that has a large impact on patients' lives. In addition to Western medicine, the use of additional treatments, such as acupuncture, in treating the positive, negative, and cognitive symptoms is increasing. Methods: We conducted a systematic review on the use of acupuncture as an add-on treatment for patients with schizophrenia that are in regular care, with a special focus on the treatment of the often accompanying sleep disorders. In this study, we searched the Medline, ScienceDirect, Cochrane Library, Scopus, and ERIC databases with a cut-off date of 31 December 2017, thereby following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) protocol. Results: Our search resulted in 26 eligible studies with 1181 patients with schizophrenia who received acupuncture treatment. Most studies showed limited evidence for the use of acupuncture as add-on therapy in the treatment of the positive, negative, and cognitive symptoms, but beneficial effects have been reported in the treatment of the accompanying sleep disorders. Conclusions: Limited evidence was found for the use of acupuncture as add-on therapy in the treatment of patients with schizophrenia; however, positive results were found in the treatment of sleep disorders, but this result needs to be confirmed in large, randomized, controlled trials.

Assessment of functioning and disability in patients with schizophrenia using the WHO Disability Assessment Schedule 2.0 in a large-scale database

Schizophrenia is a common mental disorder characterized by deficits in multiple domains of functioning. This study is arguably the first of its kind in Taiwan to examine, in a multifaceted and objective manner, the disability of patients with schizophrenia and the factors affecting it. A cross-sectional design was adopted to gather data from 24,299 patients with schizophrenia who were listed in the Taiwan Databank of Persons with Disabilities. The level of disability in these patients was measured using the World Health Organization Disability Assessment Schedule 2.0. Statistical analyses were conducted through the χ ² statistic and Poisson regression. The highest level of disability was in participation and the lowest was in self-care. An analysis of disability in all six domains of functioning on the basis of sex, age, type of residence, and socioeconomic status (SES) showed significant differences (P < 0.05). Significant factors (P < 0.05) affecting disability in these domains were female gender, age, educational attainment, SES, type of residence, and employment status. The overall degree of disability in schizophrenia patients was moderate. Six domains were measured in this study. The degrees of disability in mobility and self-care were mild while cognition, getting along, life activities, and participation were moderate. Moreover, female gender, an age of 45 or older, low educational attainment, middle to low SES, staying at healthcare institutions, and unemployment were crucial factors affecting disability of the participants. Preventive and rehabilitation programs should be developed to delay disability and functional degeneration in schizophrenic patients with these characteristics.

The role of genetic liability in the association of urbanicity at birth and during upbringing with schizophrenia in Denmark

BACKGROUND

Studies have indicated that the association of urbanicity at birth and during upbringing with schizophrenia may be driven by familial factors such as genetic liability. We used a population-based nested case-control study to assess whether polygenic risk score (PRS) for schizophrenia was associated with urbanicity at birth and at age 15, and to assess whether PRS and parental history of mental disorder together explained the association between urbanicity and schizophrenia.

METHODS

Data were drawn from Danish population registries. Cases born since 1981 and diagnosed with schizophrenia between 1994 and 2009 were matched to controls with the same sex and birthdate (1549 pairs). Genome-wide data were obtained from the Danish Neonatal Screening Biobank and PRSs were calculated based on results of a separate, large meta-analysis.

RESULTS

Those with higher PRS were more likely reside in the capital compared with rural areas at age 15 [odds ratio (OR) 1.19, 95% confidence interval (CI) 1.01-1.40], but not at birth (OR 1.09, 95% CI 0.95-1.26). Adjustment for PRS produced almost no change in relative risks of schizophrenia associated with urbanicity at birth, but slightly attenuated those for urban residence at age 15. Additional adjustment for parental history led to slight attenuation of relative risks for urbanicity at birth [incidence rate ratio (IRR) for birth in capital = 1.54, 95% CI 1.18-2.02; overall p = 0.016] and further attenuation of relative risks for urbanicity at age 15 (IRR for residence in capital = 1.32, 95% CI 0.97-1.78; overall p = 0.148).

CONCLUSIONS

While results regarding urbanicity during upbringing were somewhat equivocal, genetic liability as measured here does not appear to explain the association between urbanicity at birth and schizophrenia.

Coercion: an understudied issue in mental health

Coercion in mental health services is a controversial practice, yet it is a relatively understudied area. This special themed edition draws upon research from the international community with the aim of addressing issues related to coercion and involuntary admission. The issue covers topics such as community treatment orders, service users' perspectives, alternative models of involving service users in their treatment, and future directions for coercion research. It is hoped that this edition will encourage funding and inspire future research on this important topic.

IQ, the Urban Environment, and Their Impact on Future Schizophrenia Risk in Men

Exposure to an urban environment during early life and low IQ are 2 well-established risk factors for schizophrenia. It is not known, however, how these factors might relate to one another. Data were pooled from the North Jutland regional draft board IQ assessments and the Danish Conscription Registry for men born between 1955 and 1993. Excluding those who were followed up for less than 1 year after the assessment yielded a final cohort of 153170 men of whom 578 later developed a schizophrenia spectrum disorder. We found significant effects of having an urban birth, and also experiencing an increase in urbanicity before the age of 10 years, on adult schizophrenia risk. The effect of urban birth was independent of IQ. However, there was a significant interaction between childhood changes in urbanization in the first 10 years and IQ level on the future adult schizophrenia risk. In short, those subjects who moved to more or less urban areas before their 10th birthday lost the protective effect of IQ. When thinking about adult schizophrenia risk, the critical time window of childhood sensitivity to changes in urbanization seems to be linked to IQ. Given the prediction that by 2050, over 80% of the developed world's population will live in an urban environment, this represents a major future public health issue.

Schizophrenia in mid-adulthood after prenatal exposure to the Chinese Famine of 1959-1961

Analyzing data from a large-scale, nationally representative sample, this study examines the association between prenatal exposure to the Chinese Famine (1959-1961) and schizophrenia risk in mid-adulthood and its urban/rural-specific and gender-specific patterns. The results showed that the cohort conceived and born during the famine had a higher risk of schizophrenia in mid-adulthood than cohorts conceived and born before or after the famine. In addition, schizophrenia risk was higher for urban residents than for rural residents and higher for females than for males. Drawing on the psychiatric features of late-onset schizophrenia in mid-adulthood, we then offer some theoretical mechanisms to explain the cohort, urban/rural, and gender differences.

Women and schizophrenia: planning for the future

The aim of this narrative review is to provide readers with a summary of the recent literature on women and schizophrenia and to address commonly asked questions about the role of gender in this illness. Important gender distinctions were found in the knowledge base around schizophrenia, particularly in the areas of symptom onset, hormonal and immune effects, and antipsychotic drug kinetics and their consequences. We also discuss and address commonly asked questions about gender and schizophrenia. This review concludes that gender differences influence the effectiveness of various treatments and need to be taken into account when planning comprehensive care services for individuals with schizophrenia.

Relationship between Occupational Stress, 5-HT2A Receptor Polymorphisms and Mental Health in Petroleum Workers in the Xinjiang Arid Desert: A Cross-Sectional Study

At present, there is growing interest in research examining the relationship between occupational stress and mental health. Owing to the socioeconomic impact of occupational stress and the unique environment of petroleum workers in Xinjiang, a cross-sectional study was carried out between April and December 2015 to investigate the relationship between occupational stress, 5-hydroxytryptamine receptor (5-HTR2A) genotype, and mental health. A total of 1485 workers were selected. The Symptom Checklist 90 was used to assess nine classes of psychological symptoms. Work-related stressors were evaluated using the Occupational Stress Inventory-Revised Edition. Levels of 5-HTR2A (the Tl02C and A-1438G single nucleotide polymorphism in the 5-HTR2A gene) were measured by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). The findings of the present study revealed a high prevalence rate of mental health problems (40.29%) in petroleum workers stationed in the arid desert, and suggested a strong correlation between occupational stress and mental health. The TC and CC genotype of Tl02C were found to be protective factors against mental health problems (odds ratio (OR) = 0.455, 95% confidence interval (CI): = 0.269–0.771, odds ratio (OR) = 0.340, 95% confidence interval (CI): 0.162–0.716). AG and GG genotype of A-1438G [odds ratio (OR) 1 = 2.729, 95% confidence interval (CI): 1.433–5.195; odds ratio (OR) 2 = 2.480, 95% confidence interval (CI): 1.221–5.037] were revealed as risk factors. These data provide evidence that occupational stress and 5-HTR2A gene polymorphism contributes to the incidence of mental health problems.

Environmental pollution and risk of psychotic disorders: A review of the science to date

Environmental pollution is a global problem with diverse and substantial public health implications. Although many environmental (i.e., non-genetic) risk factors for schizophrenia and other psychotic disorders have been identified, there has been comparatively little research on pollution as a possible risk factor. This is despite the fact that gene-by-environment interactions and epigenetic mechanisms are now recognized as likely facets of the etiology of schizophrenia, and the fact that pollution could potentially mediate the association between urban birth/upbringing and elevated risk. We conducted a review of the literature to date in order to summarize and synthesize work in this area. We identified 13 research reports and 16 review articles. Based on the extant knowledge in this area and what is known about the pathophysiology of schizophrenia, it is feasible that exposure to xenobiotic heavy metals such as lead and cadmium, constituents of air pollution such as particulate matter and nitrogen and sulfur oxides, organic solvents, and other constituents of environmental pollution could be component causes. Further research-from the cellular to epidemiological levels-is clearly needed. If causation is proven, enhancements of policy intended to reduce human exposure to environmental pollution could reduce the burden of schizophrenia and possibly other mental illnesses.

No Evidence of Association between Childhood Urban Environment and Cortical Thinning in Psychotic Disorder

Background

The alterations in cortical morphology, such as cortical thinning, observed in psychotic disorder, may be the outcome of interacting genetic and environmental effects. It has been suggested that urban upbringing may represent a proxy environmental effect impacting cortical thickness (CT). Therefore, the current study examined whether the association between group as a proxy genetic variable (patients with psychotic disorder [high genetic risk], healthy siblings of patients [intermediate risk] and healthy control subjects [average risk]) and CT was conditional on different levels of the childhood urban environment and whether this was sex-dependent.

Methods

T1-weighted MRI scans were acquired from 89 patients with a psychotic disorder, 95 non-psychotic siblings of patients with psychotic disorder and 87 healthy control subjects. Freesurfer software was used to measure CT. Developmental urban exposure was classified as low, medium, and high, reflecting the population density and the number of moves between birth and the 15^th birthday, using data from the Dutch Central Bureau of Statistics and the equivalent database in Belgium. Multilevel regression analyses were used to examine the association between group, sex, and urban upbringing (as well as their interactions) and cortical CT as the dependent variable.

Results

CT was significantly smaller in the patient group compared to the controls (B = -0.043, p <0.001), but not in the siblings compared to the controls (B = -0.013, p = 0.31). There was no main effect of developmental urbanicity on CT (B = 0.001, p = 0.91). Neither the three-way group × urbanicity × sex interaction (χ² = 3.73, p = 0.16), nor the two-way group × urbanicity interaction was significant (χ² = 0.51, p = 0.77).

Conclusion

The negative association between (familial risk for) psychotic disorder and CT was not moderated by developmental urbanicity, suggesting that reduced CT is not the outcome of familial sensitivity to the proxy environmental factor ‘urban upbringing’.

Why Are Children in Urban Neighborhoods at Increased Risk for Psychotic Symptoms? Findings From a UK Longitudinal Cohort Study

BACKGROUND

Urban upbringing is associated with a 2-fold adulthood psychosis risk, and this association replicates for childhood psychotic symptoms. No study has investigated whether specific features of urban neighborhoods increase children's risk for psychotic symptoms, despite these early psychotic phenomena elevating risk for schizophrenia and other psychiatric disorders in adulthood.

METHODS

Analyses were conducted on over 2000 children from the Environmental Risk (E-Risk) Longitudinal Twin Study, a nationally-representative cohort of UK-born twins. Neighborhood-level characteristics were assessed for each family via: a geodemographic discriminator indexing neighborhood-level deprivation, postal surveys of over 5000 residents living alongside the children, and in-home interviews with the children's mothers. Children were interviewed about psychotic symptoms at age 12. Analyses were adjusted for important family-level confounders including socioeconomic status (SES), psychiatric history, and maternal psychosis.

RESULTS

Urban residency at age-5 (OR = 1.80, 95% CI = 1.16-2.77) and age-12 (OR = 1.76, 95% CI = 1.15-2.69) were both significantly associated with childhood psychotic symptoms, but not with age-12 anxiety, depression, or antisocial behavior. The association was not attributable to family SES, family psychiatric history, or maternal psychosis, each implicated in childhood mental health. Low social cohesion, together with crime victimization in the neighborhood explained nearly a quarter of the association between urbanicity and childhood psychotic symptoms after considering family-level confounders.

CONCLUSIONS

Low social cohesion and crime victimization in the neighborhood partly explain why children in cities have an elevated risk of developing psychotic symptoms. Greater understanding of the mechanisms leading from neighborhood-level exposures to psychotic symptoms could help target interventions for emerging childhood psychotic symptoms.

Education as a predictor of antidepressant and anxiolytic medication use after bereavement: a population-based record linkage study

Purpose

Educational attainment has been shown to be positively associated with mental health and a potential buffer to stressful events. One stressful life event likely to affect everyone in their lifetime is bereavement. This paper assesses the effect of educational attainment on mental health post-bereavement.

Methods

By utilising large administrative datasets, linking Census returns to death records and prescribed medication data, we analysed the bereavement exposure of 208,332 individuals aged 25–74 years. Two-level multi-level logistic regression models were constructed to determine the likelihood of antidepressant medication use (a proxy of mental ill health) post-bereavement given level of educational attainment.

Results

Individuals who are bereaved have greater antidepressant use than those who are not bereaved, with over a quarter (26.5 %) of those bereaved by suicide in receipt of antidepressant medication compared to just 12.4 % of those not bereaved. Within individuals bereaved by a sudden death, those with a university degree or higher qualifications are 73 % less likely to be in receipt of antidepressant medication compared to those with no qualifications, after full adjustment for demographic, socio-economic and area factors (OR 0.27, 95 % CI 0.09,0.75). Higher educational attainment and no qualifications have an equivalent effect for those bereaved by suicide.

Conclusions

Education may protect against poor mental health, as measured by the use of antidepressant medication, post-bereavement, except in those bereaved by suicide. This is likely due to the improved cognitive, personal and psychological skills gained from time spent in education.

Electronic supplementary material

The online version of this article (doi:10.1007/s11136-016-1440-1) contains supplementary material, which is available to authorized users.

Gene × Environment Interactions in Schizophrenia: Evidence from Genetic Mouse Models

The study of gene × environment, as well as epistatic interactions in schizophrenia, has provided important insight into the complex etiopathologic basis of schizophrenia. It has also increased our understanding of the role of susceptibility genes in the disorder and is an important consideration as we seek to translate genetic advances into novel antipsychotic treatment targets. This review summarises data arising from research involving the modelling of gene × environment interactions in schizophrenia using preclinical genetic models. Evidence for synergistic effects on the expression of schizophrenia-relevant endophenotypes will be discussed. It is proposed that valid and multifactorial preclinical models are important tools for identifying critical areas, as well as underlying mechanisms, of convergence of genetic and environmental risk factors, and their interaction in schizophrenia.

Prevalence of schizophrenia in China between 1990 and 2010

BACKGROUND

Dramatic development and changes in lifestyle in many low and middle-income countries (LMIC) over the past three decades may have affected mental health of their populations. Being the largest country and having the most striking record of development, industrialization and urbanization, China provides an important opportunity for studying the nature and magnitude of possible effects.

METHODS

We reviewed CNKI, WanFang and PubMed databases for epidemiological studies of schizophrenia in mainland China published between 1990 and 2010. We identified 42 studies that reported schizophrenia prevalence using internationally recognized diagnostic criteria, with breakdown by rural and urban residency. The analysis involved a total of 2 284 957 persons, with 10 506 diagnosed with schizophrenia. Bayesian methods were used to estimate the probability of case of schizophrenia ("prevalence") by type of residency in different years.

FINDINGS

In urban China, lifetime prevalence was 0.39% (0.37-0.41%) in 1990, 0.57% (0.55-0.59%) in 2000 and 0.83% (0.75-0.91%) in 2010. In rural areas, the corresponding rates were 0.37% (0.34-0.40%), 0.43% (0.42-0.44%) and 0.50% (0.47-0.53%). In 1990 there were 3.09 (2.87-3.32) million people in China affected with schizophrenia during their lifetime. The number of cases rose to 7.16 (6.57-7.75) million in 2010, a 132% increase, while the total population increased by 18%. The contribution of cases from urban areas to the overall burden increased from 27% in 1990 to 62% in 2010.

CONCLUSIONS

The prevalence of schizophrenia in China has more than doubled between 1990 and 2010, with rates being particularly high in the most developed areas of modern China. This has broad implications, as the ongoing development in LMIC countries may be increasing the global prevalence of schizophrenia.

Neighbourhood level social deprivation and the risk of psychotic disorders: a systematic review

PURPOSE

The incidence of psychotic disorders varies according to the geographical area, and it has been investigated whether neighbourhood level factors may be associated with this variation. The aim of this systematic review is to collate and appraise the literature on the association between social deprivation and the incidence or risk for psychotic disorders.

METHOD

A systematic review was conducted, and studies were included if they were in English, provided a measure of social deprivation for more than one geographically defined area and examined either the correlation, rate ratio or risk of psychotic disorder. A defined search strategy was undertaken with Medline, CINAHL Plus and PsychInfo databases.

RESULTS

A total of 409 studies were identified in the search, of which 28 fulfilled the inclusion criteria. Of these, four examined the association between social deprivation at the time of birth, three examined the putative prodrome of psychosis or those at ultra-high risk (UHR) for psychosis, and 23 examined the time at presentation with a first episode of psychosis (FEP) (one study examined two time points and one study included both UHR and FEP). Three of the studies that examined the level of social deprivation at birth found an association with a higher risk for psychotic disorders and increased social deprivation. Seventeen of the 23 studies found that there was a higher risk or rate of psychotic disorders in more deprived neighbourhoods at the time of presentation; however, adjusting for individual factors tended to weaken this association. Limited research has been conducted in the putative prodromal stage and has resulted in conflicting findings.

CONCLUSIONS

Research conducted to date has not definitively identified whether the association is a result of social causation or social drift; however, the findings do have significant implications for service provision, such as the location and access of services.

Socioeconomic status at birth and risk for first episode psychosis in rural Ireland: Eliminating the features of urbanicity in the Cavan-Monaghan First Episode Psychosis Study (CAMFEPS)

BACKGROUND

There is a paucity of research on the relationship between social environment at birth and risk for psychosis in rural settings. This study examined the relationship between individual- and neighbourhood-level socioeconomic indicators proximal to the time of birth and risk for a first psychotic episode in a rural context using a prospective dataset of unusual epidemiological completeness.

METHODS

A matched case-control design was used. 186 cases were identified from the Cavan-Monaghan First Episode Psychosis Study (CAMFEPS) and 679 age- and sex-matched controls from the same rural setting were identified and analysed for relationships with individual and neighbourhood-level socioeconomic indicators at the level of Electoral Divisions.

RESULTS

While neither the distribution nor the ordinal scale of parental social class differed between cases and controls, logistic regression revealed both parental social class III and increasing level of rurality to be associated (p≤0.05) with reduced risk for affective psychosis. There was a prominent relationship (p<0.001) between lower parental social class and older age at first presentation [mean age at first presentation for all psychoses: social class I, 22.8; social class VI, 44.3].

CONCLUSIONS

These findings indicate modest effects of individual- and neighbourhood-level socioeconomic indicators and risk for psychosis by place at birth within a rural environment. Thus, these factors are not confined to large urban settings and apply across the urban-rural continuum. The substantive finding in relation to age at first presentation may indicate that a gradient of socioeconomic position is influential on delay in presentation to mental health services.

Neighbourhood characteristics and the incidence of first-episode psychosis and duration of untreated psychosis

BACKGROUND

The incidence of psychotic disorders varies between geographical areas and it has been hypothesized that neighbourhood-level factors may influence this variation. It is also plausible that the duration of untreated psychosis (DUP) is associated with neighbourhood characteristics. The aims of this study were to determine whether the incidence of first-episode psychosis (FEP) and the DUP are associated with the level of social deprivation, fragmentation, social capital and population density.

METHOD

All individuals with a FEP from a geographical defined catchment area over a 5-year period were included. Age-standardized incidence rates were calculated for each neighbourhood factor.

RESULTS

A total of 292 cases of FEP were included in the study and 45% had a diagnosis of a schizophrenia-spectrum disorder. The age standardized incidence rate of FEP in the most deprived area was 72.4 [95% confidence interval (CI) 26.4-162.7] per 100 000 person-years compared with 21.5 (95% CI 17.6-26.0) per 100 000 person-years in the most affluent areas. This represents a 3.4-fold increase in FEP incidence in the most deprived areas. The incidence of FEP was also increased in neighbourhoods that were more socially fragmented [incidence rate ratio (IRR) = 2.40, 95% CI 1.05-5.51, p = 0.04] and there was a trend for the incidence to be increased in neighbourhoods with lower social capital (IRR = 1.43, 95% CI 0.99-2.06, p = 0.05). The median DUP was 4 months and was higher in more socially fragmented neighbourhoods.

CONCLUSIONS

The incidence of psychotic disorders is related to neighbourhood factors and it may be useful to consider neighbourhood factors when allocating resources for early intervention services.

Molecular genetic models related to schizophrenia and psychotic illness: heuristics and challenges

Schizophrenia is a heritable disorder that may involve several common genes of small effect and/or rare copy number variation, with phenotypic heterogeneity across patients. Furthermore, any boundaries vis-à-vis other psychotic disorders are far from clear. Consequently, identification of informative animal models for this disorder, which typically relate to pharmacological and putative pathophysiological processes of uncertain validity, faces considerable challenges. In juxtaposition, the majority of mutant models for schizophrenia relate to the functional roles of a diverse set of genes associated with risk for the disorder or with such putative pathophysiological processes. This chapter seeks to outline the evidence from phenotypic studies in mutant models related to schizophrenia. These have commonly assessed the degree to which mutation of a schizophrenia-related gene is associated with the expression of several aspects of the schizophrenia phenotype or more circumscribed, schizophrenia-related endophenotypes; typically, they place specific emphasis on positive and negative symptoms and cognitive deficits, and extend to structural and other pathological features. We first consider the primary technological approaches to the generation of such mutants, to include their relative merits and demerits, and then highlight the diverse phenotypic approaches that have been developed for their assessment. The chapter then considers the application of mutant phenotypes to study pathobiological and pharmacological mechanisms thought to be relevant for schizophrenia, particularly in terms of dopaminergic and glutamatergic dysfunction, and to an increasing range of candidate susceptibility genes and copy number variants. Finally, we discuss several pertinent issues and challenges within the field which relate to both phenotypic evaluation and a growing appreciation of the functional genomics of schizophrenia and the involvement of gene × environment interactions.

The Designed Environment and How it Affects Brain Morphology and Mental Health

Background:

The environment is inextricably related to mental health. Recent research replicates findings of a significant, linear correlation between a childhood exposure to the urban environment and psychosis. Related studies also correlate the urban environment and aberrant brain morphologies. These findings challenge common beliefs that the mind and brain remain neutral in the face of worldly experience.

Aim:

There is a signature within these neurological findings that suggests that specific features of design cause and trigger mental illness. The objective in this article is to work backward from the molecular dynamics to identify features of the designed environment that may either trigger mental illness or protect against it.

Method:

This review analyzes the discrete functions putatively assigned to the affected brain areas and a neurotransmitter called dopamine, which is the primary target of most antipsychotic medications. The intention is to establish what the correlations mean in functional terms, and more specifically, how this relates to the phenomenology of urban experience. In doing so, environmental mental illness risk factors are identified.

Conclusions:

Having established these relationships, the review makes practical recommendations for those in public health who wish to use the environment itself as a tool to improve the mental health of a community through design.

Animal models of gene-environment interaction in schizophrenia: A dimensional perspective

Schizophrenia has long been considered as a disorder with multifactorial origins. Recent discoveries have advanced our understanding of the genetic architecture of the disease. However, even with the increase of identified risk variants, heritability estimates suggest an important contribution of non-genetic factors. Various environmental risk factors have been proposed to play a role in the etiopathogenesis of schizophrenia. These include season of birth, maternal infections, obstetric complications, adverse events at early childhood, and drug abuse. Despite the progress in identification of genetic and environmental risk factors, we still have a limited understanding of the mechanisms whereby gene-environment interactions (G × E) operate in schizophrenia and psychoses at large. In this review we provide a critical analysis of current animal models of G × E relevant to psychotic disorders and propose that dimensional perspective will advance our understanding of the complex mechanisms of these disorders.

Environmental influence in the brain, human welfare and mental health

The developing human brain is shaped by environmental exposures--for better or worse. Many exposures relevant to mental health are genuinely social in nature or believed to have social subcomponents, even those related to more complex societal or area-level influences. The nature of how these social experiences are embedded into the environment may be crucial. Here we review select neuroscience evidence on the neural correlates of adverse and protective social exposures in their environmental context, focusing on human neuroimaging data and supporting cellular and molecular studies in laboratory animals. We also propose the inclusion of innovative methods in social neuroscience research that may provide new and ecologically more valid insight into the social-environmental risk architecture of the human brain.

Does conurbation affect the risk of poor mental health? A population based record linkage study

To determine if urban residence is associated with an increased risk of anxiety/depression independent of psychosocial stressors, concentrated disadvantage or selective migration between urban and rural areas, this population wide record-linkage study utilised data on receipt of prescription medication linked to area level indicators of conurbation and disadvantage. An urban/rural gradient in anxiolytic and antidepressant use was evident that was independent of variation in population composition. This gradient was most pronounced amongst disadvantaged areas. Migration into increasingly urban areas increased the likelihood of medication. These results suggest increasing conurbation is deleterious to mental health, especially amongst residents of deprived areas.

Social environmental risk factors for transition to psychosis in an Ultra-High Risk population

OBJECTIVE

Despite social environmental factors such as deprivation, urbanicity, migration and adversity being established risk factors for psychotic disorders, there is a paucity of knowledge on the influence of social environmental risk factors in the UHR population. Firstly, we aimed to investigate the association between social deprivation and risk of transition and secondly, we aimed to investigate the association between migration status and the risk of transition.

METHOD

UHR individuals at the Personal Assessment and Crisis Evaluation (PACE) service in Melbourne were included. Social deprivation as assessed according to postal code area of residence was obtained from census data and Cox regression analysis was used to calculate hazard ratios.

RESULTS

A total of 219 UHR individuals were included and over the median follow-up time of 4.8years, 32 individuals (14.6%) were known to have transitioned to a psychotic disorder. 8.8% of UHR individuals were first generation migrants and 41.9% were second generation migrants. The level of social deprivation was not associated with the risk of transition (p=0.83). Similarly, first or second generation migrants did not have an increased risk of transition to psychosis (p=0.84).

CONCLUSIONS

Despite being established risk factors for psychotic disorders, social deprivation and migrant status have not been found to increase the risk of transition in a UHR population.

Childhood trauma and childhood urbanicity in relation to psychotic disorder

BACKGROUND

Urban upbringing and childhood trauma are both associated with psychotic disorders. However, the association between childhood urbanicity and childhood trauma in psychosis is poorly understood. The urban environment could occasion a background of social adversity against which any effect of childhood trauma increases. Also, any impact of the urban environment on likelihood of exposure to childhood trauma could be stronger in children who later develop psychotic disorder. The aim of this study was twofold: (1) to investigate whether childhood urbanicity moderates the effect of childhood trauma, in a model predicting psychotic disorder; (2) to investigate whether there is an association between the urban environment and childhood trauma and whether this is moderated by genetic liability for psychotic disorder.

METHODS

Patients with a diagnosis of non-affective psychotic disorder (n = 1119) and 589 healthy controls from the Netherlands and Belgium were studied. Childhood trauma was assessed with the Dutch version of the Childhood Trauma Questionnaire Short Form. Urban exposure was defined at four levels, considering the population density, using data from Statistics Netherlands and the equivalent database in Belgium.

RESULTS

There was a significant interaction between childhood urbanicity on the one hand and childhood trauma on the other, indicating that trauma was significantly associated with psychotic disorder, with increasing odds ratios for higher levels of childhood urbanicity. In addition, there was weak evidence that childhood urbanicity was associated with childhood trauma in the patient group: higher levels of childhood urbanicity were associated with higher trauma scores.

CONCLUSION

The urban environment may moderate the risk-increasing effect of childhood trauma for psychotic disorder and childhood urbanicity may be a risk factor for childhood trauma in individuals who later develop psychotic disorder.

A Bayesian Approach to Latent Class Modeling for Estimating the Prevalence of Schizophrenia Using Administrative Databases

Estimating the incidence and the prevalence of psychotic disorders in the province of Quebec has been the object of some interest in recent years as a contribution to the epidemiological study of the causes of psychotic disorders being carried out primarily in UK and Scandinavia. A number of studies have used administrative data from the Régie de l'assurance maladie du Québec (RAMQ) that includes nearly all Quebec citizens to obtain geographical and temporal prevalence estimates for the illness. However, there has been no investigation of the validity of RAMQ diagnoses for psychotic disorders, and without a measure of the sensitivity and the specificity of these diagnoses, it is impossible to be confident in the accuracy of the estimates obtained. This paper proposes the use of latent class analysis to ascertain the validity of a diagnosis of schizophrenia using RAMQ data.

Urban living and psychosis--an overview

Since more than half a century, the association of urbanicity with psychosis has been explored. The research interest initially stemmed from the finding of a higher proportion of cases of psychotic disorder coming for treatment from the inner parts of cities. Subsequently, interest in the relationship of urbanicity and schizophrenia expanded and various facets of this association were explored. This narrative review provides an overview of the relationship between urbanicity and psychosis, and evaluates the link from the standpoint of causality. The review further delves into the possible risk factors and mechanisms explaining this association; both biological ones like genetic vulnerability and infections, as well as environmental ones like pollution. Since the literature has primarily emerged from the developed western countries, the review draws attention to the caveats while extrapolating the results to a developing country scenario.

The urban risk and migration risk factors for schizophrenia: are cats the answer?

Being born in and/or raised in an urban area is a proven risk factor for developing schizophrenia. Migrating from countries such as Jamaica or Morocco to countries such as England or the Netherlands is also a proven risk factor for developing schizophrenia. The transmission of Toxoplasma gondii oocysts to children is reviewed and proposed as a partial explanation for both of these risk factors.

Evidence that childhood urban environment is associated with blunted stress reactivity across groups of patients with psychosis, relatives of patients and controls

PURPOSE

Psychosis is associated with urban upbringing, and increased emotional reactivity is associated with psychosis. The aim of this study was to examine to what degree urban upbringing impacts emotional reactivity, and how this may be relevant for psychotic disorder and familial risk of psychotic disorder.

METHODS

Patients with a diagnosis of non-affective psychotic disorder (n = 57), 59 first degree relatives of patients and 75 healthy comparison subjects were studied with the experience sampling method (a random time sampling technique to assess affective experience in relation to fluctuating stressors in the flow of daily life), to measure a change in negative affect in relation to subjective stress. Urban exposure was defined at 5 levels, considering the population density and the number of moves between birth and the 15th birthday, using data from the Dutch Central Bureau of Statistics and the equivalent database in Belgium.

RESULTS

Multilevel random regression analyses showed that urban upbringing was consistently and strongly associated with a reduced increase in negative affect in relation to SS in adulthood in a dose-response fashion in all three groups. Regression coefficients in the patient group decreased from 0.148 (p < 0.001) in the lowest urbanicity level to 0.094 (p < 0.001) in the highest urbanicity level.

CONCLUSION

The findings suggest that urban upbringing may occasion "habituation" rather than "sensitization" across groups, which may or may not be relevant for the onset of psychotic disorder.

Aetiology of schizophrenia and implications for nursing practice: a literature review

Schizophrenia is recognised as a major mental illness and is prevalent in approximately 1% of the global population. This paper reviewed literature published between 2001 and 2013 to explore the aetiology of schizophrenia and discuss implications for mental health nursing practice. Although the causes of schizophrenia are largely unknown, there is a strong correlation between identified physiological and environmental markers and the development of the disease. With this knowledge, mental health nurses can potentially contribute to the development of strategies and approaches to complement current treatments, and therefore ensure improved outcomes for mental health clients.

Perceived discrimination and psychotic experiences across multiple ethnic groups in the United States

OBJECTIVE

The objective of this study was to examine the relationship between perceived discrimination and psychotic experiences (PE) using validated measures of discrimination and a racially/ethnically diverse population-level sample.

METHODS

Data were drawn from two population-level surveys (The National Latino and Asian American Survey and The National Survey of American Life), which were analyzed together using survey weights and stratification variables. The analytic sample (N=8990) consisted of Latino, Asian, African-American, and Afro-Caribbean adults living in the United States. Separate unadjusted and adjusted multivariable logistic regression models were used, first to examine the crude bivariate relationship between perceived discrimination and PE, and second to examine the relationship adjusting for demographic variables. Adjusted logistic regression models were also used to examine the relationships between perceived discrimination and specific sub-types of PE (auditory and visual hallucinatory experiences, and delusional ideation).

RESULTS

When compared to individuals who did not report any discrimination, those who reported the highest levels of discrimination were significantly more likely to report both 12-month PE (Adjusted OR=4.590, p<0.001) and lifetime PE (adjusted OR=4.270, p<0.001). This held true for visual hallucinatory experiences (adjusted OR=3.745, p<0.001), auditory hallucinatory experiences (adjusted OR=5.649, p<0.001), and delusional ideation (adjusted OR=7.208, p<0.001).

CONCLUSION

Perceived discrimination is associated with the increased probability of reporting psychotic experiences in a linear Fashion in the US general population.

Identifying gene-environment interactions in schizophrenia: contemporary challenges for integrated, large-scale investigations

Recent years have seen considerable progress in epidemiological and molecular genetic research into environmental and genetic factors in schizophrenia, but methodological uncertainties remain with regard to validating environmental exposures, and the population risk conferred by individual molecular genetic variants is small. There are now also a limited number of studies that have investigated molecular genetic candidate gene-environment interactions (G × E), however, so far, thorough replication of findings is rare and G × E research still faces several conceptual and methodological challenges. In this article, we aim to review these recent developments and illustrate how integrated, large-scale investigations may overcome contemporary challenges in G × E research, drawing on the example of a large, international, multi-center study into the identification and translational application of G × E in schizophrenia. While such investigations are now well underway, new challenges emerge for G × E research from late-breaking evidence that genetic variation and environmental exposures are, to a significant degree, shared across a range of psychiatric disorders, with potential overlap in phenotype.

Demographic features and premorbid personality disorder traits in relation to age of onset and sex in paranoid schizophrenia

Personality disorders in the premorbid period of schizophrenia and particularly in relation to age of onset and sex, seem to be a rather under-researched area. In the present study, 88 patients with paranoid schizophrenia were examined, regarding demographic characteristics and premorbid personality disorder traits, in order to investigate for differences in the premorbid period of the disease, in relation to age of onset and sex. Age cutoff points were set at <30 years and ≥35 years of age for young and late onset groups, respectively. The Structured Clinical Interview for DSM-IV-Patient Edition for Axis I disorders (SCID-P) was used prospectively for diagnoses. Premorbid personality disorder traits were retrospectively assessed by using the Structured Clinical Interview for DSM-IV-Patient Edition for Axis II disorders (SCID-II). Comparisons were performed by applying the two-tailed Wilcoxon rank-sum and the χ(2) statistical tests. Young onset patients were characterized by significantly higher proportion of urban birth, single status, more avoidant premorbid personality disorder traits, and less passive-aggressive premorbid personality disorder traits, than late onset counterparts. Differences were more prominently shown in men. Earlier age of onset seems to be associated to increased social inhibition and worse psychosocial adaptation in the premorbid period of paranoid schizophrenia.

Rural-urban variation in incidence of psychosis in France: a prospective epidemiologic study in two contrasted catchment areas

BACKGROUND

The aim of our study is to provide data on the incidence of psychotic disorders in France and compare the incidence rates in populations with different levels of urbanization.

METHODS

We prospectively included the incident cases of psychotic disorders from two catchment areas with contrasted levels of urbanization. In the more rural area, we also calculated incidence rates in three different groups of population defined by the size of towns in which they live (small, medium and large towns).

RESULTS

The annual incidence of psychosis was greater in the urban area (36.02/100000 person-year at risk) than in the rural area (17.2/100000 person-year at risk).Non-affective psychoses were the majority of cases and their incidence was greater in males and younger subjects. The affective psychoses were slightly more frequent in women and showed less variation with age. In the rural centre, greater levels of urbanicity were associated with an increase in the incidence of all psychoses (affective and non-affective).

CONCLUSIONS

Our study confirms previous observations of increased incidence rates for non-affective psychoses in the more urbanized areas and suggests that a similar pattern might be present for affective psychoses.

Differential neurodevelopmental trajectories in patients with early-onset bipolar and schizophrenia disorders

Schizophrenia and bipolar disorders share not only clinical features but also some risk factors such as genetic markers and childhood adversity, while other risk factors such as urbanicity and obstetric complications seem to be specific to schizophrenia. An intriguing question is whether the well-established abnormal neurodevelopment present in many children and adolescents who eventually develop schizophrenia is also present in bipolar patients. The literature on adult bipolar patients is controversial. We report data on a subgroup of patients with pediatric-onset psychotic bipolar disorder who seem to share some developmental trajectories with patients with early-onset schizophrenia. These early-onset psychotic bipolar patients have low intelligence quotient, more neurological signs, reduced frontal gray matter at the time of their first psychotic episode, and greater brain changes than healthy controls in a pattern similar to early-onset schizophrenia cases. However, patients with early-onset schizophrenia seem to have more social impairment, developmental abnormalities (eg, language problems), and lower academic achievement in childhood than early-onset bipolar patients. We suggest that some of these abnormal developmental trajectories are more related to the phenotypic features (eg, early-onset psychotic symptoms) of these 2 syndromes than to categorically defined Diagnostic and Statistical Manual of Mental Disorders disorders.

The emerging molecular architecture of schizophrenia, polygenic risk scores and the clinical implications for GxE research

Schizophrenia is a devastating mental disorder. The level of risk in the general population is sustained by the persistence of social, environmental and biological factors, as well as their interactions. Socio-environmental risk factors for schizophrenia are well established and robust. The same can belatedly be said of genetic risk factors for the disorder. Recent progress in schizophrenia genetics is primarily fuelled by genome-wide association, which is able to leverage substantial proportions of additional explained variance previously classified as 'missing'. Here, we provide an outline of the emerging genetic landscape of schizophrenia and demonstrate how this knowledge can be turned into a simple empirical measure of genetic risk, known as a polygenic risk score. We highlight the statistical framework used to assess the clinical potential of the new score and finally, draw relevance to and discuss the clinical implications for the study of gene-environment interaction.