Urbanicity during upbringing and bipolar affective disorders in Denmark

Small area variations in non-affective first-episode psychosis: the role of socioeconomic and environmental factors

BACKGROUND

There is strong evidence supporting the association between environmental factors and increased risk of non-affective psychotic disorders. However, the use of sound statistical methods to account for spatial variations associated with environmental risk factors, such as urbanicity, migration, or deprivation, is scarce in the literature.

METHODS

We studied the geographical distribution of non-affective first-episode psychosis (NA-FEP) in a northern region of Spain (Navarra) during a 54-month period considering area-level socioeconomic indicators as putative explanatory variables. We used several Bayesian hierarchical Poisson models to smooth the standardized incidence ratios (SIR). We included neighborhood-level variables in the spatial models as covariates.

RESULTS

We identified 430 NA-FEP cases over a 54-month period for a population at risk of 365,213 inhabitants per year. NA-FEP incidence risks showed spatial patterning and a significant ecological association with the migrant population, unemployment, and consumption of anxiolytics and antidepressants. The high-risk areas corresponded mostly to peripheral urban regions; very few basic health sectors of rural areas emerged as high-risk areas in the spatial models with covariates.

DISCUSSION

Increased rates of unemployment, the migrant population, and consumption of anxiolytics and antidepressants showed significant associations linked to the spatial-geographic incidence of NA-FEP. These results may allow targeting geographical areas to provide preventive interventions that potentially address modifiable environmental risk factors for NA-FEP. Further investigation is needed to understand the mechanisms underlying the associations between environmental risk factors and the incidence of NA-FEP.

The social determinants of mental health and disorder: evidence, prevention and recommendations

People exposed to more unfavourable social circumstances are more vulnerable to poor mental health over their life course, in ways that are often determined by structural factors which generate and perpetuate intergenerational cycles of disadvantage and poor health. Addressing these challenges is an imperative matter of social justice. In this paper we provide a roadmap to address the social determinants that cause mental ill health. Relying as far as possible on high-quality evidence, we first map out the literature that supports a causal link between social determinants and later mental health outcomes. Given the breadth of this topic, we focus on the most pervasive social determinants across the life course, and those that are common across major mental disorders. We draw primarily on the available evidence from the Global North, acknowledging that other global contexts will face both similar and unique sets of social determinants that will require equitable attention. Much of our evidence focuses on mental health in groups who are marginalized, and thus often exposed to a multitude of intersecting social risk factors. These groups include refugees, asylum seekers and displaced persons, as well as ethnoracial minoritized groups; lesbian, gay, bisexual, transgender and queer (LGBTQ+) groups; and those living in poverty. We then introduce a preventive framework for conceptualizing the link between social determinants and mental health and disorder, which can guide much needed primary prevention strategies capable of reducing inequalities and improving population mental health. Following this, we provide a review of the evidence concerning candidate preventive strategies to intervene on social determinants of mental health. These interventions fall broadly within the scope of universal, selected and indicated primary prevention strategies, but we also briefly review important secondary and tertiary strategies to promote recovery in those with existing mental disorders. Finally, we provide seven key recommendations, framed around social justice, which constitute a roadmap for action in research, policy and public health. Adoption of these recommendations would provide an opportunity to advance efforts to intervene on modifiable social determinants that affect population mental health.

A comparison of neighbourhood level variation and risk factors for affective versus non-affective psychosis

BACKGROUND

Studies typically highlight area level variation in the incidence of non-affective but not affective psychoses. We compared neighbourhood-level variation for both types of disorder, and the specific effects of neighbourhood urbanicity and ethnic density, using Danish national registry data.

METHODS

Population based cohort (2,224,464 people) followed from 1980 to 2013 with neighbourhood exposure measured at age 15 and incidence modelled using multilevel Poisson regression.

RESULTS

Neighbourhood variation was similar for both disorders with an adjusted median risk ratio of 1.37 (95% CI 1.34-1.39) for non-affective psychosis and 1.43 (1.38-1.49) for affective psychosis. Associations with neighbourhood urbanicity differed: living in the most compared to the least urban quintile at age 15 was associated with a minimal increase in subsequent affective psychosis, IRR 1.13 (1.01-1.27) but a substantial increase in rates of non-affective psychosis, IRR 1.66 (1.57-1.75). Mixed results were found for neighbourhood ethnic density: for Middle Eastern migrants there was an increased average incidence of both affective, IRR 1.54 (1.19-1.99), and non-affective psychoses, 1.13 (1.04-1.23) associated with each decrease in ethnic density quintile, with a similar pattern for African migrants, but for European migrants ethnic density appeared to be associated with non-affective psychosis only.

CONCLUSIONS

While overall variation and the effect of neighbourhood ethnic density were similar for both types of disorder, associations with urbanicity were largely confined to non-affective psychosis. This may reflect differences in aetiological pathways although the mechanism behind these differences remains unknown.

Neighborhood-Level Predictors of Age-at-First-Diagnosis of Psychotic Disorders: A Swedish Register-Based Cohort Study

The relationship between neighborhood-level factors and the incidence of psychotic disorders is well established. However, it is unclear whether neighborhood characteristics are also associated with age-at-first-diagnosis of these disorders. We used linked Swedish register data to identify a cohort of persons first diagnosed with an ICD-10 non-affective or affective psychotic disorder (F20-33) between 1997 and 2016. Using multilevel mixed-effect linear modelling, we investigated whether neighborhood deprivation and population density at birth were associated with age-at-first diagnosis of a psychotic disorder. Our final cohort included 13,440 individuals, with a median age-at-first-diagnosis of 21.8 years for women (interquartile range [IQR]: 19.0-25.5) and 22.9 years for men (IQR: 20.1-26.1; P < .0001). In an unadjusted model, we found no evidence of an association between neighborhood deprivation and age-at-first-diagnosis of psychotic disorder (P = .07). However, after multivariable adjustment, age-at-first-diagnosis increased by .13 years (95% CI: .05 to .21; P = .002) for a one standard deviation increase in neighborhood deprivation. This was equivalent to a later diagnosis of 47 days (95% CI: 18 to 77). We found no evidence of a different relationship for non-affective versus affective psychoses [LRT χ 2(1) = .14; P = .71]. Population density was not associated with age-at-first-diagnosis in unadjusted (P = .81) or adjusted (P = .85) models. Later age-at-first-diagnosis for individuals born in more deprived neighborhoods suggests structural barriers in accessing equitable psychiatric care.

Factors that contribute to urban-rural gradients in risk of schizophrenia: Comparing Danish and Western Australian registers

INTRODUCTION

An association between schizophrenia and urbanicity has long been observed, with studies in many countries, including several from Denmark, reporting that individuals born/raised in densely populated urban settings have an increased risk of developing schizophrenia compared to those born/raised in rural settings. However, these findings have not been replicated in all studies. In particular, a Western Australian study showed a gradient in the opposite direction which disappeared after adjustment for covariates. Given the different findings for Denmark and Western Australia, our aim was to investigate the relationship between schizophrenia and urbanicity in these two regions to determine which factors may be influencing the relationship.

METHODS

We used population-based cohorts of children born alive between 1980 and 2001 in Western Australia (N = 428,784) and Denmark (N = 1,357,874). Children were categorised according to the level of urbanicity of their mother's residence at time of birth and followed-up through to 30 June 2015. Linkage to State-based registers provided information on schizophrenia diagnosis and a range of covariates. Rates of being diagnosed with schizophrenia for each category of urbanicity were estimated using Cox proportional hazards models adjusted for covariates.

RESULTS

During follow-up, 1618 (0.4%) children in Western Australia and 11,875 (0.9%) children in Denmark were diagnosed with schizophrenia. In Western Australia, those born in the most remote areas did not experience lower rates of schizophrenia than those born in the most urban areas (hazard ratio = 1.02 [95% confidence interval: 0.81, 1.29]), unlike their Danish counterparts (hazard ratio = 0.62 [95% confidence interval: 0.58, 0.66]). However, when the Western Australian cohort was restricted to children of non-Aboriginal Indigenous status, results were consistent with Danish findings (hazard ratio = 0.46 [95% confidence interval: 0.29, 0.72]).

DISCUSSION

Our study highlights the potential for disadvantaged subgroups to mask the contribution of urban-related risk factors to risk of schizophrenia and the importance of stratified analysis in such cases.

Understanding urbanicity: how interdisciplinary methods help to unravel the effects of the city on mental health

Twenty-first century urbanization poses increasing challenges for mental health. Epidemiological studies have shown that mental health problems often accumulate in urban areas, compared to rural areas, and suggested possible underlying causes associated with the social and physical urban environments. Emerging work indicates complex urban effects that depend on many individual and contextual factors at the neighbourhood and country level and novel experimental work is starting to dissect potential underlying mechanisms. This review summarizes findings from epidemiology and population-based studies, neuroscience, experimental and experience-based research and illustrates how a combined approach can move the field towards an increased understanding of the urbanicity-mental health nexus.

Schizophrenia: Developmental Variability Interacts with Risk Factors to Cause the Disorder: Nonspecific Variability-Enhancing Factors Combine with Specific Risk Factors to Cause Schizophrenia

A new etiological model is proposed for schizophrenia that combines variability-enhancing nonspecific factors acting during development with more specific risk factors. This model is better suited than the current etiological models of schizophrenia, based on the risk factors paradigm, for predicting and/or explaining several important findings about schizophrenia: high co-morbidity rates, low specificity of many risk factors, and persistence in the population of the associated genetic polymorphisms. Compared with similar models, e.g., de-canalization, common psychopathology factor, sexual-selection, or differential sensitivity to the environment, this proposal is more general and integrative. Recently developed research methods have proven the existence of genetic and environmental factors that enhance developmental variability. Applying such methods to newly collected or already available data can allow for testing the hypotheses upon which this model is built. If validated, this model may change the understanding of the etiology of schizophrenia, the research models, and preventionbrk paradigms.

Urban environment and psychiatric disorders: a review of the neuroscience and biology

Most of the world's population now lives in cities. While living in cities have both health risks and benefits, mental health has been usually considered to be negatively affected by urbanicity. While mental health disorders have complex etiology and multiple causes, it has been shown in multiple observational studies that mood and anxiety disorders are more prevalent in urban centers and incidence has been increasing. In addition, the incidence of schizophrenia is strongly increased in people born and raised in cities. Studies on the effects of urbanicity on the brain, however, are more challenging to conduct, since individual and environmental factors are hard to distinguish. The main objective of this article is to review studies on how specific neural processes mediate those associations between urbanicity and psychiatric disorders and how environmental factors affect genetic regulation (epigenetics). Neuroimaging studies have shown how urban stressors might affect the brain by conducting experiments using functional magnetic resonance imaging (fMRI). There have been demonstrations that urban upbringing and city living have dissociable impacts on social evaluative stress processing in humans. City living was associated with increased amygdala activity and the urban upbringing has been shown to affect the perigenual anterior cingulate cortex, a key region for regulation of amygdala activity, negative affect and stress. In addition, studies on epigenetics have shown associations between exposure to features of the environment and methylation patterns. The goal of understanding how urban environments act as a risk factor for mental disorders may be pursued on several levels. It can be approached by measuring the effects of economic factors (unemployment, socioeconomic status), social condition (social network support), environmental exposures (toxins, air pollution, noise, light), that must be weighed to identify how it contributes to mental disorders.

120th Anniversary of the Kraepelinian Dichotomy of Psychiatric Disorders

PURPOSE OF REVIEW

Emil Kraepelin, in 1899, proposed a dichotomy of psychiatric disorders into "dementia praecox," further called schizophrenia, and "manisch-depressives Irresein," now conceptualized as a bipolar disorder. The purpose of the review is to show both similarities and differences between disorders involved in this dichotomy, speaking for and against the idea.

RECENT FINDINGS

On the molecular genetic side, there are data for both a genetic overlap and genetic differences between these two illnesses. Among pharmacological treatment, lithium, valproates, and carbamazepine present evidence for Kraepelinian dichotomy while atypical antipsychotics speak against this. The recent results for similarities and differences in the immune system, cognitive functions, and neurodevelopmental mechanisms have also been presented and discussed. As of 2019, the Kraepelinian dichotomy has been still partly valid although the results of recent clinical, neurobiological, and pharmacological studies provided a large number of data for an intermediate space between schizophrenia and bipolar disorder.

Association of Lithium in Drinking Water With the Incidence of Dementia

IMPORTANCE

Results from animal and human studies suggest that lithium in therapeutic doses may improve learning and memory and modify the risk of developing dementia. Additional preliminary studies suggest that subtherapeutic levels, including microlevels of lithium, may influence human cognition.

OBJECTIVE

To investigate whether the incidence of dementia in the general population covaries with long-term exposure to microlevels of lithium in drinking water.

DESIGN, SETTING, AND PARTICIPANTS

This Danish nationwide, population-based, nested case-control study examined longitudinal, individual geographic data on municipality of residence and data from drinking water measurements combined with time-specific data from all patients aged 50 to 90 years with a hospital contact with a diagnosis of dementia from January 1, 1970, through December 31, 2013, and 10 age- and sex-matched control individuals from the Danish population. The mean lithium exposure in drinking water since 1986 was estimated for all study individuals. Data analysis was performed from January 1, 1995, through December 31, 2013.

MAIN OUTCOMES AND MEASURES

A diagnosis of dementia in a hospital inpatient or outpatient contact. Diagnoses of Alzheimer disease and vascular dementia were secondary outcome measures. In primary analyses, distribution of lithium exposure was compared between patients with dementia and controls.

RESULTS

A total of 73 731 patients with dementia and 733 653 controls (median age, 80.3 years; interquartile range, 74.9-84.6 years; 44 760 female [60.7%] and 28 971 male [39.3%]) were included in the study. Lithium exposure was statistically significantly different between patients with a diagnosis of dementia (median, 11.5 µg/L; interquartile range, 6.5-14.9 µg/L) and controls (median, 12.2 µg/L; interquartile range, 7.3-16.0 µg/L; P < .001). A nonlinear association was observed. Compared with individuals exposed to 2.0 to 5.0 µg/L, the incidence rate ratio (IRR) of dementia was decreased in those exposed to more than 15.0 µg/L (IRR, 0.83; 95% CI, 0.81-0.85; P < .001) and 10.1 to 15.0 µg/L (IRR, 0.98; 95% CI, 0.96-1.01; P = .17) and increased with 5.1 to 10.0 µg/L (IRR, 1.22; 95% CI, 1.19-1.25; P < .001). Similar patterns were found with Alzheimer disease and vascular dementia as outcomes.

CONCLUSIONS AND RELEVANCE

Long-term increased lithium exposure in drinking water may be associated with a lower incidence of dementia in a nonlinear way; however, confounding from other factors associated with municipality of residence cannot be excluded.

Effects of environmental risks and polygenic loading for schizophrenia on cortical thickness

There are established differences in cortical thickness (CT) in schizophrenia (SCZ) and bipolar (BD) patients when compared to healthy controls (HC). However, it is unknown to what extent environmental or genetic risk factors impact on CT in these populations. We have investigated the effect of Environmental Risk Scores (ERS) and Polygenic Risk Scores for SCZ (PGRS-SCZ) on CT. Structural MRI scans were acquired at 3T for patients with SCZ or BD (n=57) and controls (n=41). Cortical reconstructions were generated in FreeSurfer (v5.3). The ERS was created by determining exposure to cannabis use, childhood adverse events, migration, urbanicity and obstetric complications. The PGRS-SCZ were generated, for a subset of the sample (Patients=43, HC=32), based on the latest PGC GWAS findings. ANCOVAs were used to test the hypotheses that ERS and PGRS-SCZ relate to CT globally, and in frontal and temporal lobes. An increase in ERS was negatively associated with CT within temporal lobe for patients. A higher PGRS-SCZ was also related to global cortical thinning for patients. ERS effects remained significant when including PGRS-SCZ as a fixed effect. No relationship which survived FDR correction was found for ERS and PGRS-SCZ in controls. Environmental risk for SCZ was related to localised cortical thinning in patients with SCZ and BD, while increased PGRS-SCZ was associated with global cortical thinning. Genetic and environmental risk factors for SCZ appear therefore to have differential effects. This provides a mechanistic means by which different risk factors may contribute to the development of SCZ and BD.

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.

Urban-rural differences in incidence rates of psychiatric disorders in Denmark

BACKGROUND

People born in densely populated areas have a higher risk of developing schizophrenia, bipolar disorder and autism.

AIMS

The purpose of this study was to investigate whether urban-rural differences in place of birth influence a broad range of mental disorders.

METHOD

Population-based cohort study of everyone born in Denmark between 1955 and 2006 (n = 2 894 640). Main outcome measures were incidence rate ratios for five levels of urbanisation and summary estimates contrasting birth in the capital with birth in rural areas.

RESULTS

For all psychiatric disorders, except intellectual disability (ICD-10 'mental retardation') and behavioural and emotional disorders with onset in childhood, people born in the capital had a higher incidence than people born in rural areas.

CONCLUSIONS

Birth in an urban environment is associated with an increased risk for mental illness in general and for a broad range of specific psychiatric disorders. Given this new evidence that urban-rural differences in incidence are not confined to the well-studied psychotic disorders, further work is needed to identify the underlying aetiopathogenic mechanisms.

Social and spatial heterogeneity in psychosis proneness in a multilevel case-prodrome-control study

OBJECTIVE

To test whether spatial and social neighbourhood patterning of people at ultra-high risk (UHR) of psychosis differs from first-episode psychosis (FEP) participants or controls and to determine whether exposure to different social environments is evident before disorder onset.

METHOD

We tested differences in the spatial distributions of representative samples of FEP, UHR and control participants and fitted two-level multinomial logistic regression models, adjusted for individual-level covariates, to examine group differences in neighbourhood-level characteristics.

RESULTS

The spatial distribution of controls (n = 41) differed from UHR (n = 48; P = 0.04) and FEP participants (n = 159; P = 0.01), whose distribution was similar (P = 0.17). Risk in FEP and UHR groups was associated with the same neighbourhood-level exposures: proportion of single-parent households [FEP adjusted odds ratio (aOR): 1.56 95% CI: 1.00-2.45; UHR aOR: 1.59; 95% CI: 0.99-2.57], ethnic diversity (FEP aOR: 1.27; 95% CI: 1.02-1.58; UHR aOR: 1.28; 95% CI: 1.00-1.63) and multiple deprivation (FEP aOR: 0.88; 95% CI: 0.78-1.00; UHR aOR: 0.86; 95% CI: 0.76-0.99).

CONCLUSION

Similar neighbourhood-level exposures predicted UHR and FEP risk, whose residential patterning was closer to each other's than controls. Adverse social environments are associated with psychosis before FEP onset.

Childhood residential mobility, schizophrenia, and bipolar disorder: a population-based study in Denmark

INTRODUCTION

Childhood adversity is gaining increasing attention as a plausible etiological factor in the development of psychotic disorders. Childhood residential mobility is a potential risk factor that has received little attention in this context.

METHODS

We used registry data to estimate associations of residential mobility with narrow and broad schizophrenia and bipolar disorder across the course of childhood among 1.1 million individuals born in Denmark 1971-1991 and followed from age 15 through 2010. We assessed effect modification by sex, family history of mental disorder, the presence of siblings close in age, and distance moved.

RESULTS

In individual-year models adjusted for family history, urbanicity at birth, and parental age, mobility at all ages except the year of birth was associated with heightened risk of narrow and broad schizophrenia, and risk increased with age at moving and with the number of moves. Further adjustment for mobility at all ages 0-15 revealed associations mainly during the latter half of childhood, which were strongest during adolescence. Associations between mobility and bipolar disorder were fewer and weaker compared to schizophrenia. There was modest evidence of interaction with family history of psychiatric diagnosis, but little evidence for interaction by sex, the presence of closely-aged siblings, or distance moved. Schizophrenia associations did not appear attributable to increased mobility among adolescents with earlier onset.

CONCLUSIONS

Mobility may increase risk for psychotic disorders, particularly schizophrenia. Children may be especially vulnerable during adolescence. Future research should investigate the importance of school changes and the potential for interaction with genetic risk.

Urbanicity and autism spectrum disorders

The etiology of autism spectrum disorders (ASD) is for the majority of cases unknown and more studies of risk factors are needed. Geographic variation in ASD occurrence has been observed, and urban residence has been suggested to serve as a proxy for etiologic and identification factors in ASD. We examined the association between urbanicity level and ASD at birth and during childhood. The study used a Danish register-based cohort of more than 800,000 children of which nearly 4,000 children were diagnosed with ASD. We found a dose-response association with greater level of urbanicity and risk of ASD. This association was found for residence at birth as well as residence during childhood. Further, we found an increased risk of ASD in children who moved to a higher level of urbanicity after birth. Also, earlier age of ASD diagnosis in urban areas was observed. While we could not directly examine the specific reasons behind these associations, our results demonstrating particularly strong associations between ASD diagnosis and post-birth migration suggest the influence of identification-related factors such as access to services might have a substantive role on the ASD differentials we observed.

First-contact incidence of psychosis in north-eastern Italy: influence of age, gender, immigration and socioeconomic deprivation

BACKGROUND

Considerable variations in the incidence of psychosis have been observed across countries, in terms of age, gender, immigration status, urbanicity and socioeconomic deprivation.

AIMS

To evaluate the incidence rate of first-episode psychosis in a large area of north-eastern Italy and the distribution of the above-mentioned risk factors in individuals with psychoses.

METHOD

Epidemiologically based survey. Over a 3-year period individuals with psychosis on first contact with services were identified and diagnosed according to ICD-10 criteria.

RESULTS

In total, 558 individuals with first-episode psychosis were identified during 3,077,555 person-years at risk. The annual incidence rate per 100,000 was 18.1 for all psychoses, 14.3 for non-affective psychoses and 3.8 for affective psychoses. The rate for all psychoses was higher in young people aged 20-29 (incidence rate ratio (IRR) = 4.18, 95% CI 2.77-6.30), immigrants (IRR = 2.26, 95% CI 1.85-2.75) and those living in the most deprived areas (IRR = 2.09, 95% CI 1.54-2.85).

CONCLUSIONS

The incidence rate in our study area was lower than that found in other European and North American studies and provides new insights into the factors that may increase and/or decrease risk for developing psychosis.

Finnish Prenatal Study of Bipolar Disorders (FIPS-B): overview, design and description of the sample

BACKGROUND

Bipolar disorders (BPD) are chronic mental illnesses, the development of which involves genetic factors and environmental influences.

AIMS

The aim of this paper is to provide an overall description of the Finnish Prenatal Study of Bipolar Disorders (FIPS-B), including the study design, national registers and linkage of the registers.

METHODS

FIPS-B is a population-based prenatal epidemiological study of BPD with a nested case-control study design using several national registers. The registers used are: the Finnish Medical Birth Register (FMBR), the Finnish Hospital Discharge Register (FHDR), the Population Central Register and the Finnish Maternity Cohort (FMC), which are linked using the unique personal identity code (PIC). FIPS-B includes all children born from January 1, 1983 to December 31, 1998 and diagnosed with BPD in Finland by December 31, 2008.

RESULTS

The total number of cases included in the FIPS-B is 1887. The age at first diagnosis ranged from 4 to 25 years. Half (50.4%) of the cases utilized only outpatient services, 12.7% only inpatient services and the rest (36.9%) utilized both services. Offspring of mothers with the lowest educational level had an increased odds of BPD (OR = 1.46, 95% CI 1.13-1.88). The cumulative incidence of BPD in the population aged 25 years or younger was 11.6/10,000 in 2008.

CONCLUSIONS

FIPS-B has all the strengths of a register-based prenatal epidemiological study, along with the availability of maternal biomarkers, enabling it to examine several prenatal, perinatal and familial risk factors for BPD.

Perinatal factors and the risk of bipolar disorder in Finland

BACKGROUND

Complications during the perinatal period have been associated with neurodevelopmental disorders like schizophrenia and autism. However, similar studies on bipolar disorder (BPD) have been limited and the findings are inconsistent. The aim of this study was to examine the association between perinatal risk factors and BPD.

METHODS

This nested case-control study, based on the Finnish Prenatal Study of Bipolar Disorders (FIPS-B), identified 724 cases and 1419 matched controls from population based registers. Conditional logistic regression was used to examine the associations between perinatal factors and BPD adjusting for potential confounding due to maternal age, psychiatric history and educational level, place of birth, number of previous births and maternal smoking during pregnancy.

RESULTS

Children delivered by planned cesarean section had a 2.5-fold increased risk of BPD (95% CI: 1.32-4.78, P<0.01). No association was seen between other examined perinatal risk factors and BPD.

LIMITATIONS

The limitations of this study include: the restriction in the sample to treated cases of BPD in the population, and usage of hospital based clinical diagnosis for case ascertainment. In addition, in spite of the large sample size, there was low power to detect associations for certain exposures including the lowest birth weight category and pre-term birth.

CONCLUSIONS

Birth by planned cesarean section was associated with risk of BPD, but most other perinatal risk factors examined in this study were not associated with BPD. Larger studies with greater statistical power to detect less common exposures and studies utilizing prospective biomarker-based exposures are necessary in the future.

Social deprivation, inequality, and the neighborhood-level incidence of psychotic syndromes in East London

Although urban birth, upbringing, and living are associated with increased risk of nonaffective psychotic disorders, few studies have used appropriate multilevel techniques accounting for spatial dependency in risk to investigate social, economic, or physical determinants of psychosis incidence. We adopted Bayesian hierarchical modeling to investigate the sociospatial distribution of psychosis risk in East London for DSM-IV nonaffective and affective psychotic disorders, ascertained over a 2-year period in the East London first-episode psychosis study. We included individual and environmental data on 427 subjects experiencing first-episode psychosis to estimate the incidence of disorder across 56 neighborhoods, having standardized for age, sex, ethnicity, and socioeconomic status. A Bayesian model that included spatially structured neighborhood-level random effects identified substantial unexplained variation in nonaffective psychosis risk after controlling for individual-level factors. This variation was independently associated with greater levels of neighborhood income inequality (SD increase in inequality: Bayesian relative risks [RR]: 1.25; 95% CI: 1.04-1.49), absolute deprivation (RR: 1.28; 95% CI: 1.08-1.51) and population density (RR: 1.18; 95% CI: 1.00-1.41). Neighborhood ethnic composition effects were associated with incidence of nonaffective psychosis for people of black Caribbean and black African origin. No variation in the spatial distribution of the affective psychoses was identified, consistent with the possibility of differing etiological origins of affective and nonaffective psychoses. Our data suggest that both absolute and relative measures of neighborhood social composition are associated with the incidence of nonaffective psychosis. We suggest these associations are consistent with a role for social stressors in psychosis risk, particularly when people live in more unequal communities.

Urbanicity, social adversity and psychosis

In recent years, there has been increasing interest in research on geographical variation in the incidence of schizophrenia and other psychoses. In this paper, we review the evidence on variation in incidence of schizophrenia and other psychoses in terms of place, as well as the individual- and area-level factors that account for this variation. We further review findings on potential mechanisms that link adverse urban environment and psychosis. There is evidence from earlier and more recent studies that urbanicity is associated with an increased incidence of schizophrenia and non-affective psychosis. In addition, considerable variation in incidence across neighbourhoods has been observed for these disorders. Findings suggest it is unlikely that social drift alone can fully account for geographical variation in incidence. Evidence further suggests that the impact of adverse social contexts - indexed by area-level exposures such as population density, social fragmentation and deprivation - on risk of psychosis is explained (confounding) or modified (interaction) by environmental exposures at the individual level (i.e., cannabis use, social adversity, exclusion and discrimination). On a neurobiological level, several studies suggest a close link between social adversity, isolation and stress on the one hand, and monoamine dysfunction on the other, which resembles findings in schizophrenia patients. However, studies directly assessing correlations between urban stress or discrimination and neurobiological alterations in schizophrenia are lacking to date.

Environmental and familial risk factors for psychotic and non-psychotic severe depression

BACKGROUND

Severe unipolar depression can be classified as either psychotic depression (PD) or non-psychotic depression (non-PD). A number of biological and clinical differences have been detected between PD and non-PD, but it remains unknown whether risk factors for the two subtypes also differ. The aim of the present study was therefore to investigate whether a number of potential risk factors influenced the risk of developing PD and non-PD to different extents.

METHODS

This is a register-based historical prospective cohort study following all 2.4 million individuals born in Denmark between 1955 and 1990. During follow-up 2183 and 9101 individuals were registered in the Danish Psychiatric Central Research Register with PD and non-PD respectively. The association between risk factors and the development of PD and non-PD was estimated by survival analysis (Poisson regression) and expressed as incidence rate ratios (IRR).

RESULTS

The most consistent finding of the study was that of a general overlap in familial and environmental risk factors for PD and non-PD. However, a parental history of bipolar disorder was a risk factor for PD (mother, IRR=1.66, p=0.003. Father, IRR=1.56, p=0.040) and not for non-PD (mother, IRR=0.92, p=0.430. Father, IRR=1.08, p=0.552). Conversely, a positive family history of schizophrenia was associated with neither PD nor non-PD LIMITATIONS: Diagnoses were assigned as part of routine clinical practice.

CONCLUSION

Our findings justify the distinction between PD and non-PD in the current diagnostic manuals. Furthermore, the fact that parental bipolar disorder and not schizophrenia was a risk factor for PD supports the Kraepelinian dichotomy.

Incidence rates and risk factors of bipolar disorder in the general population: a population-based cohort study

OBJECTIVE

To estimate the incidence rates (IRs) of bipolar I and bipolar II disorders in the general population according to sociodemographic population characteristics.

METHODS

A cohort study (during the years 1996-2007) was conducted in a general practitioners research database with a longitudinal electronic record of 800000 patients throughout the Netherlands [the Integrated Primary Care Information (IPCI) database]. Cases of bipolar disorder were identified and classified by systematic review of medical records. Age- and gender-specific IRs were calculated per calendar year, degree of urbanization, and degree of deprivation.

RESULTS

The overall IR of bipolar disorder was 0.70/10000 person-years (PY) [95% confidence interval (CI): 0.57-0.83]; the IR of bipolar I disorder was 0.43/10000 PY (95% CI: 0.34-0.55) and the IR of bipolar II disorder was 0.19/10000 PY (95% CI: 0.13-0.27). Two peaks in the age at onset of the disorder were noticed: one in early adulthood (15-24 years; 0.68/10000 PY) and a larger peak in later life (45-54 years; 1.2/10000 PY). In bipolar II disorder, only one peak, in the 45-54 year age category (IR 0.42/10000 PY), was found. The IRs of bipolar disorder were significantly higher in deprived areas. Similar rates were found for men compared to women and in urban compared to rural areas. No association was found between the onset of first (hypo)manic episode and month or season of birth.

CONCLUSIONS

We found two peaks in the age at onset of bipolar disorder, one in early adulthood and one in later life, the former consisting mainly of bipolar I disorder subjects. The incidence of bipolar disorder is higher in deprived areas. The onset of bipolar disorder is not associated with gender, urbanization, or month or season of birth.

Prevalence of bipolar spectrum disorder in Korean college students according to the K-MDQ

BACKGROUND

The purpose of this study was to assess the prevalence of bipolar spectrum disorder (BSD) in the general Korean population.

METHODS

A sample of college students (n = 1026) was stratified to reflect geographical differences accurately in Korean college students. The Korean version of the Mood Disorder Questionnaire (K-MDQ) was administered and an epidemiological survey carried out between November 2006 and February 2007. BSD was defined as a score of at least seven K-MDQ symptoms that co-occurred and resulted in minimal or more functional impairment.

RESULTS

The prevalence of BSD was 18.6% (95% confidence interval [CI] 16.2-21.0) in total, being 19.8% (95% CI 16.3-23.2) in men and 17.5% (95% CI 14.2-20.8) in women. The prevalence of BSD was more common in rural dwellers than in urban dwellers (P = 0.008, chi-square test). Univariate and multivariate regression models showed that rural residence was a significant factor associated with BSD. There were significant relationships between BSD and gender, age, and socioeconomic status.

CONCLUSION

The prevalence of BSD found in the present study is higher than that reported by other epidemiological studies in Korea and in international studies.

Incidence of schizophrenia and other psychoses in England, 1950-2009: a systematic review and meta-analyses

BACKGROUND

We 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).

OBJECTIVES

To determine variation in incidence of several psychotic disorders as above.

DATA SOURCES

Published and grey literature searches (MEDLINE, PSycINFO, EMBASE, CINAHL, ASSIA, HMIC), and identification of unpublished data through bibliographic searches and author communication.

STUDY ELIGIBILITY CRITERIA

Published 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.

PARTICIPANTS

People, 16-64 years, with first -onset psychosis, including non-affective psychoses, schizophrenia, bipolar disorder, psychotic depression and substance-induced psychosis.

STUDY APPRAISAL AND SYNTHESIS METHODS

Title, 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.

RESULTS

83 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.

LIMITATIONS

Incidence 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 FINDINGS

Incidence 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.

How genes and environmental factors determine the different neurodevelopmental trajectories of schizophrenia and bipolar disorder

The debate endures as to whether schizophrenia and bipolar disorder are separate entities or different manifestations of a single underlying pathological process. Here, we argue that this sterile argument obscures the fact that the truth lies somewhere in between. Thus, recent studies support a model whereby, on a background of some shared genetic liability for both disorders, patients with schizophrenia have been subject to additional genetic and/or environmental factors that impair neurodevelopment; for example, copy number variants and obstetric complications are associated with schizophrenia but not with bipolar disorder. As a result, children destined to develop schizophrenia show an excess of neuromotor delays and cognitive difficulties while those who later develop bipolar disorder perform at least as well as the general population. In keeping with this model, cognitive impairments and brain structural abnormalities are present at first onset of schizophrenia but not in the early stages of bipolar disorder. However, with repeated episodes of illness, cognitive and brain structural abnormalities accumulate in both schizophrenia and bipolar disorder, thus clouding the picture.

Neonatal antibodies to infectious agents and risk of bipolar disorder: a population-based case-control study

OBJECTIVE

There is a substantial evidence base linking prenatal exposure to infectious agents and an increased risk of schizophrenia. However, there has been less research examining the potential for these exposures to also contribute to risk for bipolar disorder. The aim of this study was to examine the association between neonatal markers of selected prenatal infections and risk for bipolar disorder.

METHODS

Using population-based Danish registers, we examined 127 individuals with a diagnosis of bipolar disorder, and 127 sex and day-of-birth individually matched controls. Based on neonatal dried blood spots, we measured antibodies to herpes simplex virus type 1 (HSV-1) and 2 (HSV-2), cytomegalovirus (CMV), and Toxoplasma gondii. Relative risks were calculated for the matched pairs when examined for optical density units for antibodies to each of the infectious agents.

RESULTS

There was no association between any of the neonatal markers of prenatal infection and risk of bipolar disorder.

CONCLUSIONS

In contrast with studies of schizophrenia, our analysis does not support maternal infection with HSV-1, HSV-2, CMV, or Toxoplasma gondii as risk factors for bipolar disorder. However, larger study samples are needed, and data on, for example, specific serotypes of Toxoplasma and indicators of the timing of maternal infection are still warranted.

Translating the epidemiology of psychosis into public mental health: evidence, challenges and future prospects

Genetic and environmental factors are associated with psychosis risk, but the latter present more tangible markers for prevention. We conducted a theoretical exercise to estimate the proportion of psychotic illnesses that could be prevented if we could identify and remove all factors that lead to increased incidence associated with ethnic minority status and urbanicity. Measures of impact by population density and ethnicity were estimated from incidence rate ratios [IRR] obtained from two methodologically-similar first episode psychosis studies in four UK centres. Multilevel Poisson regression was used to estimate IRR, controlling for confounders. Population attributable risk fractions [PAR] were estimated for our study population and the population of England. We considered three outcomes; all clinically relevant ICD-10 psychotic illnesses [F10-39], non-affective psychoses [F20-29] and affective psychoses [F30-39]. One thousand and twenty-nine subjects, aged 18-64, were identified over 2.4 million person-years. Up to 22% of all psychoses in England (46.9% within our study areas) could be prevented if exposures associated with increased incidence in ethnic minority populations could be removed; this is equivalent to 66.9% within ethnic minority groups themselves. For non-affective psychoses only, PAR for population density was large and significant (27.5%); joint PAR with ethnicity was 61.7%. Effect sizes for common socio-environmental risk indicators for psychosis are large; inequalities were marked. This analysis demonstrates potential importance in another light: we need to move beyond current epidemiological approaches to elucidate exact socio-environmental factors that underpin urbanicity and ethnic minority status as markers of increased risk by incorporating gene-environment interactions that adopt a multi disciplinary perspective.

Gender differences in risk factors for suicide: findings from a Swedish national cohort study

OBJECTIVE

To investigate whether childhood sociodemographic factors and parental psychopathology affect suicide risk differently in men and women.

METHOD

Cox regressions were used to calculate interaction effects of gender for childhood and parental risk factors for 8815 suicides (27% women) in a national cohort of 2.47 million people born between 1946 and 1968.

RESULTS

Low parental socioeconomic status increased suicide risk only for men, hazard ratio (HR) = 1.22 (P = 0.003 for gender interaction), while living in a metropolitan area increased the risk only for women, HR = 1.42 (P < 0.001 for gender interaction). Parental psychotic or affective disorder increased suicide risk more strongly for women (HR = 2.08), than for men (HR = 1.52) (P = 0.004 for gender interaction).

CONCLUSION

Growing up in an urban environment and parental psychotic or affective disorder are significant gender-related risk factors for suicide, both conveying higher risks in women. The mechanisms linking childhood urbanicity to increased risk of suicide in adult women stand out as an important research area for the future.

Psychosis and place

One important line of epidemiologic inquiry implicating social context in the etiology of psychosis is the examination of spatial variation in the distribution of psychotic illness. The authors conducted a systematic review of evidence from urbanicity and neighborhood studies regarding spatial variation in the incidence of psychosis in developed countries since 1950. A total of 44 studies (20 of urbanicity and 24 of neighborhood) were culled from three databases with similar time frames: Medline (1950-2007), PsychInfo (1950-2007), and Sociological Abstracts (1952-2007). With a special emphasis on social factors potentially relevant to etiology, the authors elucidated contributions, limitations, and issues related to study design, measurement, and theory. Evidence from both arenas supports a possible etiologic role for social context. Studies of urbanicity indicate that early-life exposure may be important; dose-response relations, spatial patterning of schizophrenia, and interactions with other factors may exist. Neighborhood studies indicate heterogeneity in rates, hint at spatial patterning of schizophrenia, and offer intriguing evidence implying more proximal social (as opposed to physical) exposures. The authors encourage the exploration of social pathways engaging theory, methodological advances, and the life-course perspective. They also propose a conceptual shift from studies of spatial variation in outcomes to research addressing the etiologic effect of exposures shaped by place as a reservoir of risk or resilience.

Case registers in psychiatry: do they still have a role for research and service monitoring?

PURPOSE OF REVIEW

To follow up on reviews of case register research. Literature searches over a 2-year period were conducted to determine whether psychiatric case registers still have a role for research and service monitoring.

RECENT FINDINGS

Case register research covers a wide range of topics, and is most often found in Denmark where national databases support all kinds of record linkage studies. Typically, case registers are used in studies of treated prevalence and incidence of psychiatric disorders, in research on patterns of care, as sampling frames in epidemiological studies, and in studies on risk factors and treatment outcome.

SUMMARY

Despite a wide range of research based on administrative data, stakeholders in most countries are probably not well served by current priorities. Few studies investigate longitudinal patterns of service use to evaluate healthcare policies. There is a lack of comparative record linkage studies to inform local authorities on the cooperation between mental healthcare and public services. Implementing standard tools and procedures for routine outcome assessment seems still to be in an early phase in most register areas. When case register staff can capitalize on new opportunities, old and new case registers will continue to be important for research and service monitoring.

Neighbourhood variation in the incidence of psychotic disorders in Southeast London

BACKGROUND

Urbanicity is a risk factor for schizophrenia, but it is unclear whether this risk is homogenous across urban areas.

AIMS

To determine whether the incidence of psychotic disorders varied within an urban area, beyond variation attributable to individual-level characteristics.

METHODS

All incident cases of ICD-10 psychoses from a large, 2-year, epidemiological study of first-episode psychoses in Southeast London were identified. Incidence rates for 33 wards were standardised for age, sex and ethnicity. Bayesian models produced accurate relative risk estimates that were then mapped.

RESULTS

295 cases were identified during 565,000 person-years of follow-up. We observed significant heterogeneity in relative risks for broad and non-affective psychoses (schizophrenia), but not for affective psychoses. Highest risks were observed in contiguous wards.

CONCLUSIONS

Neighbourhood variation in the incidence of non-affective psychoses could not be explained by individual-level risk, implicating neighbourhood-level socioenvironmental factors in their aetiology. The findings are consistent with classical sociological models of mental disorders.