Risk of schizophrenia, schizoaffective, and bipolar disorders by migrant status, region of origin, and age-at-migration: a national cohort study of 1.8 million people

Refugee status and the incidence of affective psychotic disorders and non-psychotic bipolar disorder: A register-based cohort study of 1.3m people in Sweden

BACKGROUND

Refugees are at increased risk of non-affective psychotic disorders, but it is unclear whether this extends to affective psychotic disorders [APD] or non-psychotic bipolar disorder [NPB].

METHODS

We conducted a nationwide cohort study in Sweden of all refugees, non-refugee migrants and the Swedish-born population, born 1 Jan 1984-31 Dec 2016. We followed participants from age 14 years until first ICD-10 diagnosis of APD or NPB. We fitted Cox proportional hazards models to estimate hazard ratios [HR] and 95 % confidence intervals [95%CI], adjusted for age, sex and family income. Models were additionally stratified by region-of-origin.

RESULTS

We followed 1.3 million people for 15.1 million person-years, including 2428 new APD cases (rate: 16.0 per 100,000 person-years; 95%CI: 15.4-16.7) and 9425 NPB cases (rate: 63.8; 95%CI: 62.6-65.1). Rates of APD were higher in refugee (HRadjusted: 2.07; 95%CI: 1.55-2.78) and non-refugee migrants (HRadjusted: 1.40; 95%CI: 1.16-1.68), but lower for NPBs for refugee (HRadjusted: 0.24; 95%CI: 0.16-0.38) and non-refugee migrants (HRadjusted: 0.34; 95%CI: 0.28-0.41), compared with the Swedish-born. APD rates were elevated for both migrant groups from Asia and sub-Saharan Africa, but not other regions. Migrant groups from all regions-of-origin experienced lower rates of NPB.

LIMITATIONS

Income may have been on the causal pathway making adjustment inappropriate.

CONCLUSIONS

Refugees experience elevated rates of APD compared with Swedish-born and non-refugee migrants, but lower rates of NPB. This specificity of excess risk warrants clinical and public health investment in appropriate psychosis care for these vulnerable populations.

Criminological and Psychiatric Profiles of Immigrant and Refugee Offenders: A Retrospective Analysis of Cases in a Forensic Setting

This study aimed to scrutinize the characteristics of immigrant and refugee offenders within our institution, focusing on factors such as immigrant status, country of birth, duration of residence in Turkey, as well as psychiatric, socio-demographic, and criminal profiles. The data were obtained through a retrospective examination of case records referred to the Observation Department of the Council of Forensic Medicine for the assessment of criminal responsibility between 2017 and 2022. The study categorized the cases into two groups: refugees and immigrants, comprising 35 and 22 offenders, respectively. Significant differences in educational levels were identified between immigrants and refugees within our study group (p < .001). Notably, drug use disorders were more prevalent among refugees, whereas alcohol use disorders were more common among immigrants, with statistical significance (p < .005). During forensic psychiatric assessments, 57.1% of refugees and 54.5% of immigrants required interpretation services. The most prevalent offense in the refugee group was homicide (37.1%), followed by child sexual abuse (28.6%). In contrast, homicide (31.8%) and theft and extortion (22.7%) were the most common offenses for the immigrant group. Six cases (10.5%) were judged to have reduced or no criminal liability. Among the cases, 52.6% had a history of prior outpatient psychiatric referrals, with the most frequent diagnosis being atypical psychosis at 10.5%. The findings underscore the necessity for additional research and targeted interventions to address the mental health and criminological complexities confronted by this vulnerable population.

Environmental risk factors for schizophrenia and bipolar disorder from childhood to diagnosis: a Swedish nested case-control study

BACKGROUND

Shared genetic risk between schizophrenia (SCZ) and bipolar disorder (BD) is well-established, yet the extent to which they share environmental risk factors remains unclear. We compare the associations between environmental exposures during childhood/prior to disorder onset with the risk of developing SCZ and BD.

METHODS

We conducted a Swedish register-based nested case-control study using 4184 SCZ cases and 18 681 BD cases diagnosed 1988-2013. Cases were matched to five controls by birth year, birth region, and sex. Conditional logistic regression was used to estimate incidence rate ratios (IRR) for SCZ and BD for each exposure (severe childhood infections, adverse childhood experiences (ACEs), substance use disorders (SUDs), urban birth/longest residence).

RESULTS

All SUD types were associated with very high risk (IRR 4.9-25.5), and all forms of ACEs with higher risk (IRR 1.5-4.3) for both disorders. In the mutually adjusted models, ACEs demonstrated slightly higher risk for BD (SCZ IRR 1.30, 1.19-1.42; BD IRR 1.49, 1.44-1.55), while for SUD, risk was higher for SCZ (SCZ IRR 9.43, 8.15-10.92; BD IRR 5.50, 5.15-5.88). Infections were associated with increased risk of BD (IRR 1.21, 1.17-1.26) but not SCZ. Urban birth and urban longest residence were associated with higher risk of SCZ (IRR 1.19, 1.03-1.37), while only the combination of urban birth and rural longest residence showed higher risk for BD (IRR 1.24, 1.13-1.35).

CONCLUSIONS

There were both shared and unique environmental risk factors: SUDs and ACEs were risk factors for both disorders, while infections were more strongly associated with BD and urbanicity with SCZ.

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.

Social Deprivation and Population Density Trajectories Before and After Psychotic Disorder Diagnosis

Importance

People with psychosis are more likely to be born and live in densely populated and socioeconomically deprived environments, but it is unclear whether these associations are a cause or consequence of disorder.

Objective

To investigate whether trajectories of exposure to deprivation and population density before and after diagnosis are associated with psychotic disorders or nonpsychotic bipolar disorder.

Design, Setting, and Participants

This nested case-control study included all individuals born in Sweden between January 1, 1982, and December 31, 2001, diagnosed for the first time with an International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) psychotic disorder or nonpsychotic bipolar disorder between their 15th birthday and cohort exit (December 31, 2016). One sex- and birth year-matched control participant per case was selected. Data analysis was performed from July 2021 to June 2023.

Exposures

The main exposures were quintiles of neighborhood-level deprivation and population density each year from birth to age 14 years and from first diagnosis until cohort exit.

Main Outcomes and Measures

The main outcomes were the odds of a serious mental illness outcome associated with trajectories of deprivation and population density, before and after diagnosis in cases. Group-based trajectory modeling was used to derive trajectories of each exposure in each period. Logistic regression was used to examine associations with outcomes.

Results

A total of 53 458 individuals (median [IQR] age at diagnosis in case patients, 23.2 [15.0-34.8] years; 30 746 [57.5%] female), including 26 729 case patients and 26 729 control participants, were studied. From birth to early adolescence, gradients were observed in exposure to deprivation and population density trajectories during upbringing and psychotic disorder, with those in the most vs least deprived (adjusted odds ratio [AOR], 1.17; 95% CI, 1.08-1.28) and most vs least densely populated (AOR, 1.49; 95% CI, 1.34-1.66) trajectories at greatest risk. A strong upward mobility trajectory to less deprived neighborhoods was associated with similar risk to living in the least deprived trajectory (AOR, 1.01; 95% CI, 0.91-1.12). Only 543 case patients (2.0%) drifted into more deprived areas after diagnosis; people with psychotic disorder were more likely to belong to this trajectory (AOR, 1.38; 95% CI, 1.16-1.65) or remain in the most deprived trajectory (AOR, 1.36; 95% CI, 1.24-1.48) relative to controls. Patterns were similar for nonpsychotic bipolar disorder and deprivation but weaker for population density.

Conclusions and Relevance

In this case-control study, greater exposure to deprivation during upbringing was associated with increased risk of serious mental illness, but upward mobility mitigated this association. People with serious mental illness disproportionately remained living in more deprived areas after diagnosis, highlighting issues of social immobility. Prevention and treatment should be proportionately located in deprived areas according to need.

Migration background, eating disorder symptoms and healthcare service utilisation: findings from the Stockholm Public Health Cohort

BACKGROUND

From a global perspective, eating disorders are increasingly common, probably because of societal transformation and improved detection. However, research on the impact of migration on the development of eating disorders is scarce, and previously reported results are conflicting.

AIMS

To explore if eating disorder symptom prevalence varies according to birth region, parents' birth region and neighbourhood characteristics, and analyse if the observed patterns match the likelihood of being in specialist treatment.

METHOD

This study uses data from a large population-based health survey (N = 47 662) among adults in Stockholm, Sweden. A general linear model for complex samples, including adjustment for gender and age, was used to explore self-reported eating disorder symptoms. Odds ratios were calculated for individual symptoms.

RESULTS

Eating disorder symptoms are substantially more common in individuals born abroad, especially for migrants from a non-European country. This holds true for all surveyed symptoms, including restrictive eating (odds ratio 5.5, 95% CI 4.5-6.7), compensatory vomiting (odds ratio 6.1, 95% CI 4.6-8.0), loss-of-control eating (odds ratio 2.6, 95% CI 2.3-3.1) and preoccupation with food (odds ratio 2.3, 95% CI 1.9-2.8). Likewise, symptoms are more common in individuals with both parents born abroad and individuals living in districts with a high percentage of migrant residents. A gap exists between district-level symptom scores and the likelihood of being in specialist eating disorder treatment.

CONCLUSIONS

These findings call for oversight of current outreach strategies, and highlight the need for efforts to reduce stigma and increase eating disorder symptom recognition in broader groups.

Migration and risk of schizophrenia and bipolar disorder: A Swedish national study

OBJECTIVE

Prior studies report increased risk of schizophrenia (SCZ) in migrants relative to the native-born population; however, few have investigated bipolar disorder (BD) and migrant characteristics which may influence risk. We aimed to examine the risk of SCZ and BD in migrants and their children relative to those of Swedish ancestry, and whether risk varied by age at migration, region of origin, sex, and parental migrant status.

METHODS

We conducted a nested case-control study using 5539 SCZ cases and 20,577 BD cases diagnosed 1988-2013, individually matched to five population-based controls by birth year and sex. Conditional logistic regression was used to evaluate the risk of SCZ and BD by migrant status, region of origin and age at migration, with models stratified by sex.

RESULTS

First-generation migrants had increased risk of SCZ and decreased risk of BD. There was a distinct pattern of risk for SCZ by age at migration. Childhood migrants from all regions had increased risk of SCZ, particularly those from Africa. In contrast, risk for BD declined with age at migration, with increased risk only in Nordic child migrants. SCZ and BD diagnoses were decreased in adult migrants, elevated in second-generation migrants (with risk differing by number of migrant parents and greater for those with migrant fathers) and higher in male migrants (vs. female).

CONCLUSIONS

Age at migration, sex, and region of origin affect risk of SCZ and BD. Further research is required to determine how migration-related factors influence disease etiology and the receipt of these diagnoses.

The prevalence of non-affective psychosis in refugee populations: A systematic review

BACKGROUND

As we face the largest refugee crisis since World War Two, research is increasingly examining the impact of forced displacement. The risk of non-affective psychosis in refugees is evidenced to be significantly greater than non-refugees, and the role of pre-, peri- and post-migratory trauma and dissociation is increasingly implicated.

AIMS

To determine the prevalence of non-affective psychosis in refugee populations.

METHOD

PRISMA guidelines were followed. Three key databases (PubMed, PsychINFO and Web of Science), Google scholar and study references were searched. The full-text of 62 studies were screened and 23 studies were eligible for inclusion. A narrative synthesis was undertaken and the Quality Assessment Tool for Quantitative Studies was used to assess methodological quality. (PROSPERO registration CRD42019152170).

RESULTS

The results were widely heterogeneous. The combined weighted average prevalence of non-affective psychosis in refugee populations was 0.9 %. Psychosis prevalence for individual psychotic symptoms was 28.4 %; 0.5 % for schizophrenia; 1.0 % for psychosis; 0.6 % for mixed psychotic disorders and 2.9 % for psychotic episodes.

CONCLUSIONS

Variations in examined populations, diagnostic and prevalence classifications, and study designs and methodologies likely contributed to heterogeneity across the data. The findings highlight a greater need to provide more specialist mental health services and trauma-focused interventions, as well as transculturally sensitive assessment and treatment to address refugee vulnerability to psychosis. Future research should examine psychosis prevalence longitudinally and in refugees-only, address methodological bias and further examine the role of trauma and dissociation in refugee psychosis prevalence.

De-Salazar P, Alegría M. Association of sociocultural stressors with bipolar disorder onset in Puerto Rican youth growing up as members of a minoritized ethnic group: results from the Boricua Youth Longitudinal Study

Background

The development of bipolar disorder is currently explained by a complex interaction of genetic and environmental factors. Less is known regarding the influence of sociocultural factors. This study aims to evaluate the incidence and impact of sociocultural factors on bipolar disorder onset in two comparable samples of youth growing up in different social settings.

Methods

We leveraged data from two urban population-based cohorts representative of Puerto Rican children growing up in either San Juan (Puerto Rico) or the South Bronx (NYC) and followed up for 17 years. Bipolar disorder diagnoses were based on retrospective self-reports on the World Health Organization Composite International Diagnostic Interview. We used a causal inference approach to estimate associations of sociocultural factors with bipolar disorder onset after adjusting for potential confounders.

Findings

We found that South Bronx children, who grew up as a minoritized group, had twice the risk of bipolar disorder onset as young adults, with an incidence rate of 2.22 new cases per 1000 person-years compared to 1.08 new cases in San Juan (incidence rate difference, 1.13; 95% CI, 0.09-1.20). After adjusting for potential confounders, South Bronx children had the same lifetime hazard of bipolar disorder onset compared to San Juan children. However, our analysis demonstrated that caregivers' exposure to societal cultural stress partially explained the increased risk of bipolar disorder onset in the South Bronx, in addition to the potential contribution of genetics.

Interpretation

Our results provide evidence that societal cultural stress can increase the risk of lifetime bipolar disorder onset in youth growing up as a minoritized group. Addressing stress in minoritized groups might reduce the risk of bipolar disorder onset.

Funding

The Boricua Youth Study has been supported by the National Institutes of HealthMH56401, MH098374, DA033172, and AA020191. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the article.

Review of Major Social Determinants of Health in Schizophrenia-Spectrum Disorders: II. Assessments

BACKGROUND AND AIMS

Social determinants of health (SDoHs) impact the development and course of schizophrenia-spectrum psychotic disorders (SSPDs). Yet, we found no published scholarly reviews of psychometric properties and pragmatic utility of SDoH assessments among people with SSPDs. We aim to review those aspects of SDoH assessments.

STUDY DESIGN

PsychInfo, PubMed, and Google Scholar databases were examined to obtain data on reliability, validity, administration process, strengths, and limitations of the measures for SDoHs identified in a paired scoping review.

STUDY RESULTS

SDoHs were assessed using different approaches including self-reports, interviews, rating scales, and review of public databases. Of the major SDoHs, early-life adversities, social disconnection, racism, social fragmentation, and food insecurity had measures with satisfactory psychometric properties. Internal consistency reliabilities-evaluated in the general population for 13 measures of early-life adversities, social disconnection, racism, social fragmentation, and food insecurity-ranged from poor to excellent (0.68-0.96). The number of items varied from 1 to more than 100 and administration time ranged from less than 5 minutes to over an hour. Measures of urbanicity, low socioeconomic status, immigration status, homelessness/housing instability, and incarceration were based on public records or targeted sampling.

CONCLUSIONS

Although the reported assessments of SDoHs show promise, there is a need to develop and test brief but validated screening measures suitable for clinical application. Novel assessment tools, including objective assessments at individual and community levels utilizing new technology, and sophisticated psychometric evaluations for reliability, validity, and sensitivity to change with effective interventions are recommended, and suggestions for training curricula are offered.

Impact of Early-Life Factors on Risk for Schizophrenia and Bipolar Disorder

BACKGROUND AND HYPOTHESIS

Schizophrenia (SCZ) and bipolar disorder (BD) have shared genetic risk and clinical symptoms, yet the extent to which environmental risk factors are shared is not well known. We aimed to examine the associations of early-life environmental exposures with the risk of SCZ and BD.

STUDY DESIGN

We conducted a Swedish register-based nested case-control study using 4184 SCZ and 18 681 BD cases diagnosed 1988-2013, individually matched to 5 population-based controls by birth year, sex and birthplace. Conditional logistic regression was used to evaluate the risk of SCZ and BD by seasonality, severe prenatal infections, and perinatal factors.

STUDY RESULTS

Seasonality had similar patterns of risk for both disorders: Higher risk for births November-December; lower risk April-June. Experiencing any perinatal factor was associated with a significantly higher risk of SCZ (incidence rate ratio [IRR] 1.19, 95%CI 1.11-1.63) and to a lesser extent BD (IRR 1.08, 95%CI 1.05-1.12). Prenatal infections were only associated with a greater risk of SCZ (IRR 1.30, 95%CI 1.04-1.63). In the mutually adjusted model, only perinatal factors were associated with outcomes. Several perinatal factors were associated with both disorders, but estimates were significantly higher for SCZ for low birth weight, low APGAR, and high parity. Congenital malformations were only associated with risk of SCZ, and jaundice with BD.

CONCLUSIONS

Adverse perinatal factors and winter birth were the risk factors for both disorders, while severe prenatal infections were only risk a factor for SCZ. Early-life exposures were associated with a higher risk of both disorders, but may play a larger role in the development of SCZ than BD.

Early childhood adversity and non-affective psychosis: a study of refugees and international adoptees in Sweden

BACKGROUND

Previous Scandinavian studies have shown increased levels of psychiatric morbidity in young refugees and international adoptees with an origin outside Europe. This study investigated their risk of non-affective psychotic disorders (NAPD) and whether this risk is influenced by early childhood adversity, operationalised as age at adoption/residency, and/or gender.

METHODS

Register study in Swedish national cohorts born 1972-1990 including 21 615 non-European international adoptees, 42 732 non-European refugees that settled in Sweden at age 0-14 years and 1 610 233 Swedish born. The study population was followed from age 18 to year 2016 for hospitalisations with a discharge diagnosis of NAPD. Hazard ratios (HRs) were calculated in gender stratified Cox regression models, adjusted for household income at age 17.

RESULTS

The adjusted risks of NAPD were 2.33 [95% confidence interval (CI) 2.07-2.63] for the international adoptees and 1.92 (1.76-2.09) for the former child refugees, relative to the Swedish-born population. For the international adoptees there was a stepwise gradient for NAPD by age of adoption from adjusted HR 1.66 (1.29-2.03) when adopted during the first year of life to adjusted HR 4.56 (3.22-6.46) when adopted at ages 5-14 years, with a similar risk pattern in women and men. Age at residency did not influence the risk of NAPD in the refugees, but their male to female risk ratio was higher than in Swedish-born and the adoptees.

CONCLUSION

The risk pattern in the international adoptees gives support to a link between early childhood adversity and NAPD. Male gender increased the risk of NAPD more among the refugees.

Is legal status associated with mental illness among newly arrived refugees in Sweden: an epidemiological study

BACKGROUND

There are about 80 million forcibly displaced people globally. Migrants are at heightened risk for mental illness compared to host country populations. While previous research highlights the need to adequately assess mental illness, few have taken the diversity among newly arrived migrants into account. This study aims to estimate the prevalence and associated risk factors of mental illness among asylum seekers, quota and other refugees in Stockholm, Sweden.

METHODS

Using a cross-sectional design, data was collected as part of a mental health screening initiative integrated into routine health examinations in two health care clinics in Stockholm. Screening was done with the Refugee Health Screener, RHS-13, a validated instrument for assessing mental health in refugee populations.

RESULTS

A total of 1163 individuals were eligible for screening, of whom 566 participated (response rate 48.6%). Among the participants, 47.9% indicated symptoms of mental illness. Compared with asylum seekers, the risk of mental illness was lower among quota and other refugees (adjusted odds ratio 0.60, 95% confidence interval 0.37-1.00). Female sex, higher age, coming from a middle-income country and low probability of being granted asylum were significant predictors of mental illness.

CONCLUSION

Refugee legal status is associated with mental illness. Asylum seekers are at greater risk of mental illness compared to quota and other refugees. Our findings call for screening for mental illness among newly arrived migrants, especially among those with pending residence permits.

Suicide among psychiatric patients who migrated to the UK: a national clinical survey

BACKGROUND

Within the UK, limited research has examined migration and suicide risk. To assist with tailoring mental health care to the needs of different migrant groups, it is important to identify the clinical profile and antecedents to suicide.

METHODS

We focussed on two groups of migrants: those resident in the UK for less than 5 years (recent migrants) and those seeking permission to stay in the UK. Data on mental health patients who died by suicide in the UK between 2011 and 2019 were obtained as part of the National Confidential Inquiry into Suicide and Safety in Mental Health.

FINDINGS

13,948 patients died by suicide between 2011 and 2019: 593 were recent migrants with 48 seeking permission to stay in the UK. The overall suicide rate between 2011 and 2017 for patients seeking to stay was 23.8/100,000 (95% CI 17.3-32.1). There was some uncertainty around this estimate but it appeared higher than the general population suicide rate of 10.6/100,000 population (95% CI 10.5-10.7; p = .0001) for the same period. A higher proportion of migrants were from an ethnic minority group (15% recent migrants vs. 70% seeking to remain vs. 7% non-migrants) and more were viewed as at low long-term risk of suicide (63% recent migrants vs. 76% seeking to remain vs. 57% non-migrants). A higher proportion of recent migrants died within three months of discharge from psychiatric in-patient care (19% vs. 14%) compared to non-migrants. Proportionally more patients seeking to remain had a diagnosis of schizophrenia and other delusional disorders (31% vs. 15%) and more had experienced recent life events compared to non-migrants (71% vs. 51%).

INTERPRETATION

A higher proportion of migrants had severe or acute illness at the time of their suicide. This may be linked to a range of serious stressors and/or lack of connection with services that could have identified signs of illness early. However, clinicians often viewed these patients as low risk. Mental health services should consider the breadth of stressors migrants may face and adopt a multi-agency approach to suicide prevention.

FUNDING

The Healthcare Quality Improvement Partnership.

Risk of Diagnosed Adolescent-Onset Non-Affective Psychotic Disorder by Migration Background in British Columbia: A Retrospective Cohort Study

OBJECTIVE

We recently found that the risk of diagnosed non-affective psychotic disorder between the ages of 13 and 19 was lower for immigrant adolescents compared to those without a personal or parental migration history in British Columbia (BC), Canada. In the current study, we further examined the risk for migrants compared to non-migrants by region of origin and immigrant generation (first vs. second), adjusting for several demographic factors and migration class.

METHODS

Administrative data were used to construct a cohort of individuals born 1990-98 and residing in South-Western BC (N = 193,400). Cases were identified by either one hospitalization or two outpatient physician visits with a primary diagnosis of a non-affective psychotic disorder. Poisson regression was used to estimate incidence rate ratios (IRR) of a diagnosed non-affective psychotic disorder by region of origin among first- and second-generation migrants compared to non-migrants, adjusting for sex, birth year, neighbourhood income and low family income.

RESULTS

Risk of diagnosed non-affective psychotic disorder was lower among first-generation migrants from East Asia (IRR = 0.34[95% CI: 0.25-0.46]), South-Asia (IRR = 0.47[95% CI: 0.25-0.89]) and South-East Asia (IRR = 0.55[95% CI: 0.32-0.93]) and second-generation migrants from East Asia (IRR = 0.49[95% CI: 0.35-0.69]) and South Asia (IRR = 0.52[95% CI: 0.37-0.73]), compared to non-migrants. Adjusting for migration class attenuated but did not fully explain variation in risk by region among first-generation migrants. No groups exhibited a significantly elevated risk of the diagnosed non-affective psychotic disorder compared to non-migrants.

CONCLUSION

Findings from this study underline the complexity of the association between migration and psychotic disorders. Future research should investigate why certain groups of migrants are less likely to be diagnosed and whether there are specific sub-groups that face an elevated risk.

The incidence of psychotic disorders among migrants and minority ethnic groups in Europe: findings from the multinational EU-GEI study

BACKGROUND

In Europe, the incidence of psychotic disorder is high in certain migrant and minority ethnic groups (hence: 'minorities'). However, it is unknown how the incidence pattern for these groups varies within this continent. Our objective was to compare, across sites in France, Italy, Spain, the UK and the Netherlands, the incidence rates for minorities and the incidence rate ratios (IRRs, minorities v. the local reference population).

METHODS

The European Network of National Schizophrenia Networks Studying Gene-Environment Interactions (EU-GEI) study was conducted between 2010 and 2015. We analyzed data on incident cases of non-organic psychosis (International Classification of Diseases, 10th edition, codes F20-F33) from 13 sites.

RESULTS

The standardized incidence rates for minorities, combined into one category, varied from 12.2 in Valencia to 82.5 per 100 000 in Paris. These rates were generally high at sites with high rates for the reference population, and low at sites with low rates for the reference population. IRRs for minorities (combined into one category) varied from 0.70 (95% CI 0.32-1.53) in Valencia to 2.47 (95% CI 1.66-3.69) in Paris (test for interaction: p = 0.031). At most sites, IRRs were higher for persons from non-Western countries than for those from Western countries, with the highest IRRs for individuals from sub-Saharan Africa (adjusted IRR = 3.23, 95% CI 2.66-3.93).

CONCLUSIONS

Incidence rates vary by region of origin, region of destination and their combination. This suggests that they are strongly influenced by the social context.

Effects of country of origin and wave of immigration on prevalence of schizophrenia among first and second-generation immigrants: A 30-year retrospective study

OBJECTIVES

To compare the rates of schizophrenia among 1st and 2nd generation immigrants from two distinct backgrounds and across sequential periods of immigration.

METHODS

A 30-years retrospective cohort study (187,184 individuals) of 1st and 2nd generation East-African immigrants (EAIs) and former Soviet-Union immigrants (FSUIs) who migrated to Israel between 1980 and 2012. EAIs were further divided according to waves of immigration. Period prevalence was calculated between the years 2002-2012. Multivariate logistic regression models were used to examine the association between immigration-related factors and prevalence of schizophrenia (Native-Born Israelis serving as reference group).

RESULTS

The prevalence of schizophrenia in 1st generation EAIs and FSUIs was 1.8% and 1.2%, respectively, compared to 1.0% among NBIs (p<0.001). The prevalence of schizophrenia among 2nd generation EAIs and FSUIs was 1.3% and 0.8%, respectively, compared to 0.6% among NBIs (p<0.001). Adjusted odds ratios for developing schizophrenia compared to NBIs were 1.6 (95%CI:1.4-1.8) and 2.1 (95%CI:1.6-2.7), among 1st and 2nd generation EAIs and 1.1 (95%CI:0.9-1.2) and 1.3 (95%CI:1.0-1.8) among 1st and 2nd generation FSUIs respectively. Among EAIs, we observed the highest rate of schizophrenia in the pioneer wave of immigrants with gradual decline across subsequent waves: 2.4%, 1.9% and 1.0% for the 1st, 2nd and 3rd waves of immigration, respectively (p<0.001).

CONCLUSIONS

The increased risk for developing schizophrenia among 2nd generation immigrants and among pioneer groups of immigrants emphasizes the importance of persistent investment in acculturation. Further studies elucidating the impact of country of origin and ethnic density on the risk for developing schizophrenia are warranted.

Comparing Risk Factors for Non-affective Psychotic Disorders With Common Mental Disorders Among Migrant Groups: A 25-Year Retrospective Cohort Study of 2 Million Migrants

BACKGROUND AND HYPOTHESIS

Although migration is a well-established risk factor for psychotic disorders, less is known about factors that modify risk within migrant groups. We sought to assess whether socio-demographic, migration-related, and post-migration factors were associated with the risk of non-affective psychotic disorders (NAPD) among first-generation migrants, and to compare with estimates for common mental disorders (CMD) to explore specificity of the effect.

STUDY DESIGN

We constructed a retrospective cohort of first-generation migrants to Ontario, Canada using linked population-based health administrative data (1992-2011; n = 1 964 884). We identified NAPD and CMD using standardized algorithms. We used modified Poisson regression models to estimate incidence rate ratios (IRR) for each factor to assess its effect on the risk of each outcome.

STUDY RESULTS

Nearly 75% of cases of NAPD met the case definition for a CMD prior to the first diagnosis of psychosis. Our findings suggest that younger age at migration, male sex, being of African-origin, and not having proficiency in national languages had a specificity of effect for a higher risk of NAPD. Among migrants who were over 19 years of age at landing, higher pre-migratory education and being married/common-law at landing showed specificity of effect for a lower risk of NAPD. Migrant class, rurality of residence after landing, and post-migration neighborhood-level income showed similar effects across disorders.

CONCLUSIONS

Our findings help identify high-risk groups to target for intervention. Identifying factors that show specific effects for psychotic disorder, rather than mental disorders more broadly, are important for informing prevention and early intervention efforts.

Migration, Schizophrenia, and Crime: A Study From a Forensic Psychiatric Sample

BACKGROUND

The association between mental health problems and crime in immigrants has attracted recent academic interest, with results suggesting that there were possible interactions between immigration, schizophrenia, and criminal behavior. However, very few studies have examined these interactions, especially in developing countries that have mass internal immigration. Therefore, this study sought to identify the associations between the sociodemographic, clinical, and criminal factors in migrants and non-migrants with schizophrenia who had been involved in criminal activities in China.

METHODS

Forensic archives of suspects who had been referred for criminal responsibility assessments in the Sichuan West China Forensic Center from January 2015 to December 2019 were reviewed. The sociodemographic, and criminal activity information of the suspects were extracted, while the clinical and social function were measured by the Brief Psychiatric Rating Scale (BPRS) and Social Disability Screening Schedule (SDSS) based on the archives. A Chi-squared test, a T-test, a Mann-Whitney U test, and Multinomial logistic regression were employed for the statistical analysis.

RESULTS

A total of 552 patients were reviewed and evaluated, 17.2% (n = 95) of which were migrants. The migrant patient group was younger than the non-migrant patient group. The BPRS and SDSS scores for the migrant patient group were lower than for the non-migrant patient group. The migrant patient group had more work experience and more had been employed at the time of the crime than the non-migrant patient group. The unemployed migrant patients were more likely to commit a property-related crime.

CONCLUSIONS

Compared to the non-migrant schizophrenia patient group, the migrant patient group had less severe psychiatric symptoms and less social function impairments. Employment was an important factor in preventing criminality in patients with schizophrenia, especially for migrant patients. Vocational rehabilitation focuses on developing appropriate employment that can significantly assist in schizophrenia patient recovery, which in turn could reduce their chances of committing crime. Besides, reducing other obstacles to stigma, housing and health insurance would also be beneficial to crime reduction.

Migrant status and risk of compulsory admission at first diagnosis of psychotic disorder: a population-based cohort study in Sweden

BACKGROUND

Minority ethnic and migrant groups face an elevated risk of compulsory admission for mental illness. There are overlapping cultural, socio-demographic, and structural explanations for this risk that require further investigation.

METHODS

By linking Swedish national register data, we established a cohort of persons first diagnosed with a psychotic disorder between 2001 and 2016. We used multilevel mixed-effects logistic modelling to investigate variation in compulsory admission at first diagnosis of psychosis across migrant and Swedish-born groups with individual and neighbourhood-level covariates.

RESULTS

Our cohort included 12 000 individuals, with 1298 (10.8%) admitted compulsorily. In an unadjusted model, being a migrant [odds ratio (OR) 1.48; 95% confidence interval (CI) 1.26-1.73] or child of a migrant (OR 1.27; 95% CI 1.10-1.47) increased risk of compulsory admission. However after multivariable modelling, region-of-origin provided a better fit to the data than migrant status; excess risk of compulsory admission was elevated for individuals from sub-Saharan African (OR 1.94; 95% CI 1.51-2.49), Middle Eastern and North African (OR 1.46; 95% CI 1.17-1.81), non-Nordic European (OR 1.27; 95% CI 1.01-1.61), and mixed Swedish-Nordic backgrounds (OR 1.33; 95% CI 1.03-1.72). Risk of compulsory admission was greater in more densely populated neighbourhoods [OR per standard deviation (s.d.) increase in the exposure: 1.12, 95% CI 1.06-1.18], an effect that appeared to be driven by own-region migrant density (OR per s.d. increase in exposure: 1.12; 95% CI 1.02-1.24).

CONCLUSIONS

Inequalities in the risk of compulsory admission by migrant status, region-of-origin, urban living and own-region migrant density highlight discernible factors which raise barriers to equitable care and provide potential targets for intervention.

Social disadvantage, linguistic distance, ethnic minority status and first-episode psychosis: results from the EU-GEI case-control study

BACKGROUND

Ethnic minority groups in Western countries face an increased risk of psychotic disorders. Causes of this long-standing public health inequality remain poorly understood. We investigated whether social disadvantage, linguistic distance and discrimination contributed to these patterns.

METHODS

We used case-control data from the EUropean network of national schizophrenia networks studying Gene-Environment Interactions (EU-GEI) study, carried out in 16 centres in six countries. We recruited 1130 cases and 1497 population-based controls. Our main outcome measure was first-episode ICD-10 psychotic disorder (F20-F33), and exposures were ethnicity (white majority, black, mixed, Asian, North-African, white minority and other), generational status, social disadvantage, linguistic distance and discrimination. Age, sex, paternal age, cannabis use, childhood trauma and parental history of psychosis were included as a priori confounders. Exposures and confounders were added sequentially to multivariable logistic models, following multiple imputation for missing data.

RESULTS

Participants from any ethnic minority background had crude excess odds of psychosis [odds ratio (OR) 2.03, 95% confidence interval (CI) 1.69-2.43], which remained after adjustment for confounders (OR 1.61, 95% CI 1.31-1.98). This was progressively attenuated following further adjustment for social disadvantage (OR 1.52, 95% CI 1.22-1.89) and linguistic distance (OR 1.22, 95% CI 0.95-1.57), a pattern mirrored in several specific ethnic groups. Linguistic distance and social disadvantage had stronger effects for first- and later-generation groups, respectively.

CONCLUSION

Social disadvantage and linguistic distance, two potential markers of sociocultural exclusion, were associated with increased odds of psychotic disorder, and adjusting for these led to equivocal risk between several ethnic minority groups and the white majority.

Environmental Risk Factors for Schizophrenia and Bipolar Disorder and Their Relationship to Genetic Risk: Current Knowledge and Future Directions

Schizophrenia (SZ) and bipolar disorder (BD) are severe psychiatric disorders which result from complex interplay between genetic and environmental factors. It is well-established that they are highly heritable disorders, and considerable progress has been made identifying their shared and distinct genetic risk factors. However, the 15-40% of risk that is derived from environmental sources is less definitively known. Environmental factors that have been repeatedly investigated and often associated with SZ include: obstetric complications, infections, winter or spring birth, migration, urban living, childhood adversity, and cannabis use. There is evidence that childhood adversity and some types of infections are also associated with BD. Evidence for other risk factors in BD is weaker due to fewer studies and often smaller sample sizes. Relatively few environmental exposures have ever been examined for SZ or BD, and additional ones likely remain to be discovered. A complete picture of how genetic and environmental risk factors confer risk for these disorders requires an understanding of how they interact. Early gene-by-environment interaction studies for both SZ and BD often involved candidate genes and were underpowered. Larger samples with genome-wide data and polygenic risk scores now offer enhanced prospects to reveal genetic interactions with environmental exposures that contribute to risk for these disorders. Overall, although some environmental risk factors have been identified for SZ, few have been for BD, and the extent to which these account for the total risk from environmental sources remains unknown. For both disorders, interactions between genetic and environmental risk factors are also not well understood and merit further investigation. Questions remain regarding the mechanisms by which risk factors exert their effects, and the ways in which environmental factors differ by sex. Concurrent investigations of environmental and genetic risk factors in SZ and BD are needed as we work toward a more comprehensive understanding of the ways in which these disorders arise.

Inequalities in Psychiatric Service Use and Mortality by Migrant Status Following a First Diagnosis of Psychotic Disorder: A Swedish Cohort Study of 1.3M People

It is unclear whether inequalities in mental healthcare and mortality following the onset of psychosis exist by migrant status and region-of-origin. We investigated whether (1) mortality (including by major causes of death); (2) first admission type (inpatient or outpatient); (3) in-patient length of stay (LOS) at first diagnosis for psychotic disorder presentation, and; (4) time-to-readmission for psychotic disorder differed for refugees, non-refugee migrants, and by region-of-origin. We established a cohort of 1 335 192 people born 1984–1997 and living in Sweden from January 1, 1998, followed from their 14th birthday or arrival to Sweden, until death, emigration, or December 31, 2016. People with ICD-10 psychotic disorder (F20–33; N = 9399) were 6.7 (95% confidence interval [95%CI]: 5.9–7.6) times more likely to die than the general population, but this did not vary by migrant status (P = .15) or region-of-origin (P = .31). This mortality gap was most pronounced for suicide (adjusted hazard ratio [aHR]: 12.2; 95% CI: 10.4–14.4), but persisted for deaths from other external (aHR: 5.1; 95%CI: 4.0–6.4) and natural causes (aHR: 2.3; 95%CI: 1.6–3.3). Non-refugee (adjusted odds ratio [aOR]: 1.4, 95%CI: 1.2–1.6) and refugee migrants (aOR: 1.4, 95%CI: 1.1–1.8) were more likely to receive inpatient care at first diagnosis. No differences in in-patient LOS at first diagnosis were observed by migrant status. Sub-Saharan African migrants with psychotic disorder were readmitted more quickly than their Swedish-born counterparts (adjusted sub-hazard ratio [sHR]: 1.2; 95%CI: 1.1–1.4). Our findings highlight the need to understand the drivers of disparities in psychosis treatment and the mortality gap experienced by all people with disorder, irrespective of migrant status or region-of-origin.

Mental disorders among young adults of immigrant background: a nationwide register study in Norway

PURPOSE

Previous research indicates increased risk of various mental disorders in immigrant populations, particularly for schizophrenia and PTSD. However, findings are inconclusive due to variations in contextual factors, characteristics of immigrant groups and study design. Our study aims to investigate prevalence differences of receiving an ICD-10 psychiatric diagnosis between 2008 and 2016 among four first-generation immigrant groups and one second-generation immigrant group compared to ethnic Norwegians.

METHODS

Linked register data from the Norwegian Patient Registry and Statistics Norway were utilised. The sample (age 18-35) comprises 758,774 ethnic Norwegians, 61,124 immigrants originating from Poland, Somalia, Iran and Pakistan and 4630 s-generation Pakistani immigrants. Age- and gender-adjusted binary logistic regression models were applied.

RESULTS

The odds of schizophrenia were significantly elevated for all groups except for Poles. The highest odds were observed for second-generation Pakistani immigrants (adjusted OR 2.72, 95% CI 2.21-3.35). For PTSD, the odds were significantly increased for Somalis (aOR 1.31, 95% CI 1.11-1.54), second-generation Pakistani immigrants (aOR 1.37, 95% CI 1.11-1.70), and in particular for Iranians (aOR 3.99, 95% CI 3.51-4.54). While Iranians showed similar or higher odds of receiving the vast majority of psychiatric diagnoses, the remaining groups showed lower or similar odds compared to ethnic Norwegians.

CONCLUSION

Our findings suggest considerable prevalence differences in receiving a psychiatric diagnosis according to country of origin and generational status compared to ethnic Norwegian controls. The general pattern was lower prevalence of most ICD-10 mental disorders for the majority of immigrant groups compared to ethnic Norwegians, except for schizophrenia and PTSD.

Exploring Similarities and Differences of Non-European Migrants among Forensic Patients with Schizophrenia

Migrants diagnosed with schizophrenia are overrepresented in forensic-psychiatric clinics. A comprehensive characterization of this offender subgroup remains to be conducted. The present exploratory study aims at closing this research gap. In a sample of 370 inpatients with schizophrenia spectrum disorders who were detained in a Swiss forensic-psychiatric clinic, 653 different variables were analyzed to identify possible differences between native Europeans and non-European migrants. The exploratory data analysis was conducted by means of supervised machine learning. In order to minimize the multiple testing problem, the detected group differences were cross-validated by applying six different machine learning algorithms on the data set. Subsequently, the variables identified as most influential were used for machine learning algorithm building and evaluation. The combination of two childhood-related factors and three therapy-related factors allowed to differentiate native Europeans and non-European migrants with an accuracy of 74.5% and a predictive power of AUC = 0.75 (area under the curve). The AUC could not be enhanced by any of the investigated criminal history factors or psychiatric history factors. Overall, it was found that the migrant subgroup was quite similar to the rest of offender patients with schizophrenia, which may help to reduce the stigmatization of migrants in forensic-psychiatric clinics. Some of the predictor variables identified may serve as starting points for studies aimed at developing crime prevention approaches in the community setting and risk management strategies tailored to subgroups of offenders with schizophrenia.

Rising inpatient numbers in forensic security hospitals of German federal state of Baden-Württemberg: Background and explanatory approaches

In this article, we describe critical epidemiological trends in forensic psychiatric care in the German federal state of Baden-Württemberg. For some years, there has been a marked increase in the number of patients with psychoses and with a migration background in the high-security hospitals of Baden-Württemberg. We present a number of studies exploring hypotheses as to why this is the case. Taking into account a set of person-related and non-person (forensic system)-related variables, we suggest that rising treatment figures may be understood in terms of system variables rather than individual patient characteristics. Findings regarding predictors of treatment length and legal outcome, as well as characteristics of migrant patients and patients assigned to forensic aftercare, are discussed.

A Latent Class Analysis of Manic and Psychotic Symptoms

Bipolar spectrum disorders encompass heterogeneous clinical manifestations and comorbidities. A latent class analysis (LCA) was performed in 1846 subjects who experienced an episode of abnormally elevated or irritable mood to identify homogeneous groups of subjects, based on the distribution of 11 manic and 7 psychotic symptoms. LCA identified five classes: 1) two classes with irritability and with low and high level of psychosis (respectively "irritable," 29.1% of the sample, and "irritable-psychotic," 16.2%); 2) a class with expansive mood and hyperactivity ("expansive-hyperactive," 12.7%); and 3) two classes with manic symptoms and high and low level of psychosis ("manic-psychotic," 15.0%, and "manic," 27.2%). "Irritable" displayed lower rates of depressive episode, panic, and substance use disorders. Manic-psychotic displayed higher rates of depressive episode, panic, generalized anxiety, and substance use disorders. Use of mental health treatment more frequent in manic-psychotic and manic classes. Five classes of bipolar spectrum disorders were characterized by different sociodemographic and clinical patterns.

Invited Commentary: Adult Child Migration and Parental Cognitive Decline-A New Perspective on Loneliness and Social Isolation

There is a growing body of research on the link between social isolation, loneliness, and health outcomes in later life, including cognitive decline and dementia. In the current issue of the Journal, Torres et al. (Am J Epidemiol. 2020;189(8):761-769) present findings from a study of the association between adult child migration status and cognitive performance among parents who stayed behind in Mexico, using longitudinal data (2001-2015) from the Mexican Health and Aging Study. This is an excellent example of the role that emotional and social factors may play in the development of cognitive impairment among older adults. In their study, having an adult child in the United States was associated with a steeper decline in verbal memory scores over time, but only among women. In the light of the increasing levels of immigration worldwide, this work is highly relevant, as it touches upon a less recognized socioemotional risk factor for cognitive decline: family-member migration status. Further research on this topic should be conducted in other countries and should include assessment of the social and emotional needs of those staying behind when a family member migrates. This will increase our understanding of how social isolation and loneliness relate to cognitive decline and may contribute to new directions for interventions.

The impact of social capital, demographic factors, and coping strategies on community adaptation in supporting people with severe mental illness

Background: People with severe mental illness have the ability to live a satisfactory and independent life with the help of the community. Their adaptation to life’s challenges is a dynamic process, and the community plays an important role. This research, therefore, aims to address the question of how social capital, demographic factors, and coping strategies affect the community’s ability to adapt to people with severe mental illness.

Design and methods: The multi-stage random sampling was used to obtain data from 137 respondents from rural society using an analytic observational design and cross-sectional approach. In addition, the Somers’ D test was used to measure the effect of social capital, demographic factors, and coping strategies on community adaptation.

Results: The results showed a significant effect of social capital, demographic factors, and the coping strategy of community adaptation (P<0.05). Based on empirical research, access to social capital is critical in fostering community adaptation through its social participation, network, trust, coping strategies, and cooperation.

Conclusions: In conclusion, social capital, demographic factors, and coping strategies are significant factors in developing community adaptation of people with severe mental illness.

Age at migration and the risk of psychotic disorders: a systematic review and meta-analysis

OBJECTIVE

To conduct a systematic review and meta-analysis of the existing evidence on the association between age at migration and the risk of psychotic disorders.

METHODS

Observational studies were eligible for inclusion if they presented data on the association between age at migration and the risk of psychotic disorders among first-generation migrant groups. We used two random effects meta-analyses to pool effect estimates for each stratum of age at migration relative to (i) a native-born reference category and (ii) the youngest age stratum (0 to 2 years).

RESULTS

Ten studies met inclusion criteria, and five were included in the meta-analysis. The risk of psychotic disorder among people who migrate prior to age 18 is nearly twice as high as the native-born population, with no evidence of effect modification by age strata. People who migrate during early adulthood (19 to 29 years) have a similar risk of psychotic disorder as the native-born population (IRR = 0.93, 95% CI = 0.60, 1.44) and a lower risk relative to those who migrate during infancy (0 to 2 years) (IRR = 0.58, 95% CI = 0.33, 1.04).

CONCLUSIONS

Migrant status is one of few well-established risk factors for psychotic disorder, yet we have limited understanding of the underlying etiology. The findings of this review advance our understanding of this association and identify high-risk groups to target for intervention.

Migration and schizophrenia: meta-analysis and explanatory framework

Systematic reviews and meta-analyses suggest that there are increased rates of schizophrenia and related psychoses in first- and second-generation migrants and refugees. Here, we present a meta-analysis on the incidence of non-affective psychotic disorders among first- and second-generation migrants. We found substantial evidence for an increased relative risk of incidence among first- and second-generation migrants compared to the native population. As heterogeneity of included studies was high, effect estimates should be interpreted with caution and as guiding values rather than exact risk estimates. We interpret our findings in the context of social exclusion and isolation stress, and provide an explanatory framework that links cultural differences in verbal communication and experienced discrimination with the emergence of psychotic experiences and their neurobiological correlates. In this context, we discuss studies observing stress-dependent alterations of dopamine neurotransmission in studies among migrants versus non-migrants as well as in subjects with psychotic disorders. We suggest that social stress effects can impair contextualization of the meaning of verbal messages, which can be accounted for in Bayesian terms by a reduced precision of prior beliefs relative to sensory data, causing increased prediction errors and resulting in a shift towards the literal or "concrete" meaning of words. Compensatory alterations in higher-level beliefs, e.g., in the form of generalized interpretations of ambiguous interactions as hostile behavior, may contribute to psychotic experiences in migrants. We thus suggest that experienced discrimination and social exclusion is at the core of increased rates of psychotic experiences in subjects with a migration background.

Association of neighbourhood migrant density and risk of non-affective psychosis: a national, longitudinal cohort study

BACKGROUND

Elevated risk of psychotic disorders in migrant groups is a public mental health priority. We investigated whether living in areas of high own-region migrant density was associated with reduced risk of psychotic disorders among migrants and their children, and whether generation status, probable visible minority status, or region-of-origin affected this relationship.

METHODS

We used the Swedish registers to identify migrants and their children born between Jan 1, 1982, and Dec 31, 1996, and living in Sweden on or after their 15th birthday. We tracked all included participants from age 15 years or date of migration until emigration, death, or study end (Dec 31, 2016). The outcome was an ICD-10 diagnosis of non-affective psychosis (F20-29). We calculated own-region and generation-specific own-region density within the 9208 small areas for market statistics neighbourhoods in Sweden, and estimated the relationship between density and diagnosis of non-affective psychotic disorders using multilevel Cox proportional hazards models, adjusting for individual confounders (generation status, age, sex, calendar year, lone dwelling, and time since migration [migrants only]), family confounders (family income, family unemployment, and social welfare), and neighbourhood confounders (deprivation index, population density, and proportion of lone dwellings), and using the Akaike information criterion (AIC) to compare model fit.

FINDINGS

Of 468 223 individuals included in the final cohort, 4582 (1·0%) had non-affective psychotic disorder. Lower own-region migrant density was associated with increased risk of psychotic disorders among migrants (hazard ratio [HR] 1·05, 95% CI 1·02-1·07 per 5% decrease) and children of migrants (1·03, 1·01-1·06), after adjustment. These effects were stronger for probable visible minority migrants (1·07, 1·04-1·11), including migrants from Asia (1·42, 1·15-1·76) and sub-Saharan Africa (1·28, 1·15-1·44), but not migrants from probable non-visible minority backgrounds (0·99, 0·94-1·04). Among migrants, adding generation status to the measure of own-region density provided a better fit to the data than overall own-region migrant density (AIC 36 103 vs 36 106, respectively), with a 5% decrease in generation-specific migrant density corresponding to a HR of 1·07 (1·04-1·11).

INTERPRETATION

Migrant density was associated with non-affective psychosis risk in migrants and their children. Stronger protective effects of migrant density were found for probable visible minority migrants and migrants from Asia and sub-Saharan Africa. For migrants, this risk intersected with generation status. Together, these results suggest that this health inequality is socially constructed.

FUNDING

Wellcome Trust, Royal Society, Mental Health Research UK, University College London, National Institute for Health Research, Swedish Research Council, and FORTE.

Substance use disorders in refugee and migrant groups in Sweden: A nationwide cohort study of 1.2 million people

BACKGROUND

Refugees are at higher risk of some psychiatric disorders, including post-traumatic stress disorder (PTSD) and psychosis, compared with other non-refugee migrants and the majority population. However, it is unclear whether this also applies to substance use disorders, which we investigated in a national register cohort study in Sweden. We also investigated whether risk varied by region of origin, age at migration, time in Sweden, and diagnosis of PTSD.

METHODS AND FINDINGS

Using linked Swedish register data, we followed a cohort born between 1984 and 1997 from their 14th birthday or arrival in Sweden, if later, until an International Classification of Diseases, 10th revision (ICD-10), diagnosis of substance use disorder (codes F10.X-19.X), emigration, death, or end of follow-up (31 December 2016). Refugee and non-refugee migrants were restricted to those from regions with at least 1,000 refugees in the Swedish registers. We used Cox proportional hazards regression to estimate unadjusted and adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) in refugee and non-refugee migrants, compared with Swedish-born individuals, for all substance use disorders (F10.X-19.X), alcohol use disorders (F10.X), cannabis use disorders (F12.X), and polydrug use disorders (F19.X). In adjusted analyses, we controlled for age, sex, birth year, family income, family employment status, population density, and PTSD diagnosis. Our sample of 1,241,901 participants included 17,783 (1.4%) refugee and 104,250 (8.4%) non-refugee migrants. Refugees' regions of origin were represented in proportions ranging from 6.0% (Eastern Europe and Russia) to 41.4% (Middle East and North Africa); proportions of non-refugee migrants' regions of origin ranged from 11.8% (sub-Saharan Africa) to 33.7% (Middle East and North Africa). These groups were more economically disadvantaged at cohort entry (p < 0.001) than the Swedish-born population. Refugee (aHR: 0.52; 95% CI 0.46-0.60) and non-refugee (aHR: 0.46; 95% CI 0.43-0.49) migrants had similarly lower rates of all substance use disorders compared with Swedish-born individuals (crude incidence: 290.2 cases per 100,000 person-years; 95% CI 287.3-293.1). Rates of substance use disorders in migrants converged to the Swedish-born rate over time, indicated by both earlier age at migration and longer time in Sweden. We observed similar patterns for alcohol and polydrug use disorders, separately, although differences in cannabis use were less marked; findings did not differ substantially by migrants' region of origin. Finally, while a PTSD diagnosis was over 5 times more common in refugees than the Swedish-born population, it was more strongly associated with increased rates of substance use disorders in the Swedish-born population (aHR: 7.36; 95% CI 6.79-7.96) than non-refugee migrants (HR: 4.88; 95% CI 3.71-6.41; likelihood ratio test [LRT]: p = 0.01). The main limitations of our study were possible non-differential or differential under-ascertainment (by migrant status) of those only seen via primary care and that our findings may not generalize to undocumented migrants, who were not part of this study.

CONCLUSIONS

Our findings suggest that lower rates of substance use disorders in migrants and refugees may reflect prevalent behaviors with respect to substance use in migrants' countries of origin, although this effect appeared to diminish over time in Sweden, with rates converging towards the substantial burden of substance use morbidity we observed in the Swedish-born population.

Family networks during migration and risk of non-affective psychosis: A population-based cohort study

OBJECTIVE

The determinants of increased psychosis risk among immigrants remain unclear. Given ethnic density may be protective, we investigated whether the presence of immediate family, or "family networks", at time of immigration was associated with risk of non-affective psychosis.

METHODS

We followed a cohort of migrants (n = 838,717) to Sweden, born 1968-1997, from their 14th birthday, or earliest immigration thereafter, until diagnosis of non-affective psychosis (ICD-9/ICD-10), emigration, death, or 2011. Using record linkage, we measured family network as the presence of adult first-degree relatives immigrating with the cohort participant or already residing in Sweden. We used Cox proportional hazards regression to examine whether risk varied between those migrating with family, migrating to join family, or migrating alone.

RESULTS

Migrating with immediate family was associated with increased psychosis risk amongst males compared to males who did not migrate with family (adjusted Hazard Ratio [aHR]: 1.16, 95% CI: 1.00-1.34). Migrating with family did not increase risk among females (aHR: 0.91, 95% CI: 0.78-1.07); similar observations were observed for males who immigrated to join family (aHR: 1.35, 95% CI: 1.21-1.51). In contrast, females who migrated alone were at increased risk compared to females who did not migrate alone (aHR: 1.31, 95% CI: 1.11-1.54).

CONCLUSION

Family networks at the time of immigration were associated with differential patterns of non-affective psychotic disorders for males and females. These results suggest sex-specific differences in the perceived role of family networks during the migration process.