Delusional ideation and manic symptoms in potential future emigrants in Uganda

Psychoses sans Frontieres: towards an interdisciplinary understanding of psychosis risk amongst migrants and their descendants

Understanding the excess risk of psychotic disorders in migrant and ethnic minority groups has long been an important research focus in psychiatric epidemiology and public mental health. Heterogeneity between migrant groups based on the region of origin, minority status and other socioeconomic factors may provide clues as to the underlying aetiological mechanisms explaining this risk, as well as informing our general understanding of psychotic disorders. Nonetheless, disentangling the mechanisms underlying this association has been the focus of more speculation and theory to date than empirical research. Now more than ever, we need to move beyond studies which demonstrate excess rates in migrant and ethnic minority groups to novel population-based studies which identify the determinants and mechanisms through which this risk is shaped. In this paper, we review the main hypotheses proposed to explain these disparities and the current level of support for them. We then highlight recent evidence from epidemiology and neuroscience which provides important new clues in our understanding of the aetiology of psychotic disorders. We concluded with suggestions for future interdisciplinary research to prevent this public mental health inequality within a generation.

Immigration and psychotic experiences in the United States: Another example of the epidemiological paradox?

In Europe, it is widely established that immigration increases risk for psychotic disorder. However, research has yet to confirm this association in the United States, where immigrants paradoxically report better health status than their native-born counterparts. Further, few studies have examined this topic with respect to sub-threshold psychotic experiences, which are more common than psychotic disorders in the general population. This study analyzes the (1) National Comorbidity Survey-Replication, (2) the National Latino and Asian American Survey, and (3) the National Survey of American Life, in order to determine whether generation status had any impact on risk for lifetime and 12-month PE, and whether these associations vary across racial/ethnic groups, adjusting for demographic variables and socioeconomic status. We found an absence of an immigration effect on PE across various ethnic groups and across various geographic areas, and found that immigration is actually protective among Latinos, supporting the idea that the epidemiological paradox extends to the psychosis phenotype.

Testing Ødegaard's selective migration hypothesis: a longitudinal cohort study of risk factors for non-affective psychotic disorders among prospective emigrants

BACKGROUND

The selection hypothesis posits that the increased rates of psychosis observed among migrants are due to selective migration of people who are predisposed to develop the disorder. To test this hypothesis, we examined whether risk factors for psychosis are more prevalent among future emigrants.

METHOD

A cohort of 49,321 Swedish military conscripts was assessed at age 18 years on cannabis use, IQ, psychiatric diagnosis, social adjustment, history of trauma and urbanicity of place of upbringing. Through data linkage we examined whether these exposures predicted emigration out of Sweden. We also calculated the emigrants' hypothetical relative risk compared with non-emigrants for developing a non-affective psychotic disorder.

RESULTS

Low IQ [odds ratio (OR) 0.5, 95% confidence interval (95% CI) 0.3-0.9] and 'poor social adjustment' (OR 0.4, 95% CI 0.2-0.8) were significantly less prevalent among prospective emigrants, whereas a history of urban upbringing (OR 2.3, 95% CI 1.4-3.7) was significantly more common. Apart from a non-significant increase in cannabis use among emigrants (OR 1.6, 95% CI 0.8-3.1), there were no major group differences in any other risk factors. Compared to non-emigrants, hypothetical relative risks for developing non-affective psychotic disorder were 0.7 (95% CI 0.4-1.2) and 0.8 (95% CI 0.7-1.0), respectively, for emigrants narrowly and broadly defined.

CONCLUSIONS

This study adds to an increasing body of evidence opposing the selection hypothesis.

Do risk factors for schizophrenia predispose to emigration?

OBJECTIVE

Increased incidence rates of schizophrenia in immigrants still lack a satisfactory explanation. The aim of this study was to examine the hypothesis that risk factors for schizophrenia also increase the risk of emigration to a foreign country. If valid, Danes emigrating from Denmark carry a higher predisposition to develop schizophrenia compared to Danes living in Denmark.

METHODS

Utilizing data from the Danish Civil Registration System, we established a population-based cohort of 1.10 million native Danes. We assessed relative risks of emigration to a foreign country in relation to sex, age, urban birth, parental age, and a history of mental illness.

RESULTS

Urban birth in Denmark was a significant predictor of emigration to a foreign country. A maternal history of psychiatric contact during childhood and a parental history of bipolar affective disorder increased the risks of emigration. A personal history of mental illness decreased the risk of emigration, mostly for people diagnosed with schizophrenia.

CONCLUSIONS

Our study provided evidence that Danish emigrants residing in a foreign country have both a higher predisposition of schizophrenia due to differential exposure to birth in urban areas and a lower predisposition of schizophrenia due to differential exposure to a history of mental illness. Although competing selection mechanisms operate, the combined effect of these different selection mechanisms was limited, thus suggesting a potential role for yet to be identified adverse environmental effects operating either before or after emigration.

Migration, ethnicity, and psychosis: toward a sociodevelopmental model

There is consistent and strong evidence that the incidence of all psychoses is higher in many migrant and minority ethnic populations in a number of countries. The reasons for this are, however, unclear and a wide range of explanations have been proposed, from genetic to neurodevelopmental to psychosocial. In this article, we describe and evaluate the available evidence for and against each of these. What this shows is that: (1) there are few studies that have directly investigated specific risk factors in migrant and minority ethnic populations, with often only 1 or 2 studies of any relevance to specific explanations and (2) what limited research there has been tends to implicate a diverse range of social factors (including childhood separation from parents, discrimination and, at an area level, ethnic density) as being of potential importance. In an attempt to synthesize these disparate findings and provide a basis for future research, we go on to propose an integrated model--of a sociodevelopmental pathway to psychosis--to account for the reported high rates in migrant and minority ethnic populations. Aspects of this model will be directly tested in a new Europe-wide incidence and case-control study that we will conduct over the next 3 years, as part of the European Network of National Schizophrenia Networks studying Gene-Environment Interactions programme.

Urbanicity of place of birth and symptoms of psychosis, depression and anxiety in Uganda

BACKGROUND

The mechanism underlying the association between urban birth/upbringing and increased schizophrenia risk is unknown. This study explored whether an urban effect might be present in a low-income country setting, where the ;urban' environment may have radically different components, for example urban architecture, pollution levels or social cohesion.

AIMS

To investigate the potential association of urbanicity of place of birth and symptoms of psychosis, depression and anxiety in Uganda.

METHOD

Ugandans aged 18-30 years (n = 646) were interviewed using the Peters et al Delusions Inventory (PDI-21), the Hopkins Symptoms Checklist (HSCL-25) and psychoticism items from the Symptoms Checklist 90-items version (SCL-90) in Mbarara and Kampala districts and asked about their birthplace.

RESULTS

Urban birth (but not semi-urban) was associated with more lifetime psychotic experiences, especially grandiosity, and more symptoms of psychosis, depression and anxiety during the past week.

CONCLUSIONS

The urban risk factor for schizophrenia may be universally present across different levels of human development, albeit the nature of the mechanism remains elusive.

Demographic correlates of psychotic-like experiences in young Australian adults

OBJECTIVE

Psychotic-like experiences (PLE) in the general community are common. The aims of this study were to examine the prevalence and demographic correlates of PLE in young adults.

METHOD

The sample consisted of 2441 subjects aged 18-23 years. Subjects completed the Composite International Diagnostic Interview (CIDI) and the 21-item Peters Delusional Inventory (PDI). Associations between age, gender, hallucinations and delusions were examined using logistic regression.

RESULTS

Both CIDI hallucinations and delusions predicted high scores on the PDI. Younger age was significantly associated with endorsement of CIDI delusions [odds ratio (OR) = 0.66, 95% confidence interval (CI) 0.48-0.92) and with PDI total scores (OR = 0.68, 95% CI 0.55-0.83). Women were significantly more likely to endorse items related to hallucinations (OR = 1.49, 95% CI 1.14-1.95) but not delusions.

CONCLUSION

PLE are common in young adults. The mechanisms underpinning the age and gender gradients in PLE may provide clues to the pathogenesis of psychotic disorders.

Psychoses, ethnicity and socio-economic status

BACKGROUND

Consistent observation of raised rates of psychoses among Black and minority ethnic (BME) groups may possibly be explained by their lower socio-economic status.

AIMS

To test whether risk for psychoses remained elevated in BME populations compared with the White British, after adjustment for age, gender and current socio-economic status.

METHOD

Population-based study of first-episode DSM-IV psychotic disorders, in individuals aged 18-64 years, in East London over 2 years.

RESULTS

All BME groups had elevated rates of a psychotic disorder after adjustment for age, gender and socio-economic status. For schizophrenia, risk was elevated for people of Black Caribbean (incidence rate ratios (IRR)=3.1, 95% CI 2.1-4.5) and Black African (IRR=2.6, 95% CI 1.8-3.8) origin, and for Pakistani (IRR=3.1, 95% CI 1.2-8.1) and Bangladeshi (IRR=2.3, 95% CI 1.1-4.7) women. Mixed White and Black Caribbean (IRR=7.7, 95% CI 3.2-18.8) and White Other (IRR=2.1, 95% CI 1.2-3.8) groups had elevated rates of affective psychoses (and other non-affective psychoses).

CONCLUSIONS

Elevated rates of psychoses in BME groups could not be explained by socio-economic status, even though current socio-economic status may have overestimated the effect of this confounder given potential misclassification as a result of downward social drift in the prodromal phase of psychosis. Our findings extended to all BME groups and psychotic disorders, though heterogeneity remains.