The relationship between schizophrenia and immigration. Are there alternatives to psychosocial hypotheses?

Psychosis, migration and social environment: an age-and-gender controlled study

Purpose

Adverse social experiences are frequently invoked to explain the higher rate of psychosis among migrant groups. The aim of the present study was to establish the socio-environmental factors distinguishing migrant psychotic patients from autochthonous patients.

Subjects and method

We conducted a cross-sectional survey involving 341 migrant psychotic patients matched for age and gender with 341 autochthonous psychotic patients.

Results

Migrant patients lived more often with their parental family, were less often enrolled with a referral psychiatrist, presented a lower rate of employment, a lower percentage of alcohol misuse and of suicide attempts.

Discussion

Our findings add to the growing body of results showing that more attention needs to be focused on socio-environmental variables in psychosis research. However, several limitations have to be taken into account, particularly with regard to selection biases and age of onset of the psychotic illness.

Conclusion

Our results are compatible with the hypothesis that unemployment is a contributing factor in the risk for psychosis among migrant groups. Migrants’ families are an important keystone in the mental health care process of their sick relatives. Our service models need to be adapted with the aim to make the treatment easier for migrant patients.

Migration, ethnicity and psychoses: evidence, models and future directions

There is a large body of research reporting high rates of psychotic disorders among many migrant and minority ethnic groups, particularly in Northern Europe. In the context of increasing migration and consequent cultural diversity in many places worldwide, these findings are a major social and public health concern. In this paper, we take stock of the current state of the art, reviewing evidence on variations in rates of psychoses and putative explanations, including relevant theories and models. We discuss in particular: a) the wide variation in reported rates of psychotic disorders by ethnic group, and b) the evidence implicating social risks to explain this variation, at ecological and individual levels. We go on to set out our proposed socio-developmental model, that posits greater exposure to systemic social risks over the life course, particularly those involving threat, hostility and violence, to explain high rates of psychoses in some migrant and minority ethnic groups. Based on this analysis, the challenge of addressing this social and public health issue needs to be met at multiple levels, including social policy, community initiatives, and mental health service reform.

Ideology, Camouflage or Contingency? Racism in British Psychiatry

"...Are we so sure that the racist form of intolerance results chiefly from the wrong ideas of this or that group of people about the dependence of cultural evolution on organic evolution? Might not these ideas be simply ideological camouflage for more concrete oppositions based on a desire to subjugate other groups and maintain a posi tion of power?"

Associations Between Sociodemographic Characteristics, Pre Migratory and Migratory Factors and Psychological Distress Just After Migration and After Resettlement: The Indian Migration Study

BACKGROUND/OBJECTIVES

Migration is suspected to increase the risk for psychological distress for those who enter a new cultural environment. We investigated the association between sociodemographic characteristics, premigratory and migratory factors and psychological distress in rural-to-urban migrants just after migration and after resettlement.

METHODS

Data from the cross-sectional sib-pair designed Indian Migration Study (IMS, 2005-2007) were used. The analysis focused on 2112 participants aged ≥18 years from the total IMS sample (n = 7067) who reported being migrant. Psychological distress was assessed based on the responses of the 7-questions in a five-point scale, where the respondents were asked to report about their feelings now and also asked to recall these feelings when they first migrated. The associations were analyzed using multiple logistic regression models.

RESULTS

High prevalence of psychological distress was found just after migration (7.3%; 95% confidence interval [CI]: 6.2-8.4) than after settlement (4.7%; 95% CI: 3.8-5.6). Push factors as a reason behind migration and not being able to adjust in the new environment were the main correlates of psychological distress among both the male and female migrants, just after migration.

CONCLUSIONS

Rural-urban migration is a major phenomenon in India and given the impact of premigratory and migratory related stressors on mental health, early intervention could prevent the development of psychological distress among the migrants.

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.

Ethnic origin and increased risk for schizophrenia in immigrants to countries of recent and longstanding immigration

OBJECTIVES

Compare the risk for schizophrenia in immigrants to countries of recent and longstanding immigration. Compare prevalence and incidence rates in black subjects under different conditions.

METHOD

An electronic literature search was complemented by review articles and cross-references. Studies reporting standard diagnosis and incidence or prevalence rates were included.

RESULTS

Immigrants had an increased risk for schizophrenia in countries of longstanding immigration, but with lower risk ratios than in those of recent immigration. The risk was higher in black immigrants and the black population living in the United States. But incidence and prevalence rates in Africa and the Caribbean were similar to those of international studies.

CONCLUSION

Comparing the most recent generation of immigrants with descendants of previous ones may account for the lower risk ratios observed in countries of longstanding vs. recent immigration. Two neurobiological hypotheses are proposed to explain the epidemiological findings in black populations and in immigrants.

Epigenetic mechanisms in schizophrenia

Epidemiological research suggests that both an individual's genes and the environment underlie the pathophysiology of schizophrenia. Molecular mechanisms mediating the interplay between genes and the environment are likely to have a significant role in the onset of the disorder. Recent work indicates that epigenetic mechanisms, or the chemical markings of the DNA and the surrounding histone proteins, remain labile through the lifespan and can be altered by environmental factors. Thus, epigenetic mechanisms are an attractive molecular hypothesis for environmental contributions to schizophrenia. In this review, we first present an overview of schizophrenia and discuss the role of nature versus nurture in its pathology, where 'nature' is considered to be inherited or genetic vulnerability to schizophrenia, and 'nurture' is proposed to exert its effects through epigenetic mechanisms. Second, we define DNA methylation and discuss the evidence for its role in schizophrenia. Third, we define posttranslational histone modifications and discuss their place in schizophrenia. This research is likely to lead to the development of epigenetic therapy, which holds the promise of alleviating cognitive deficits associated with schizophrenia.

Psychosocial factors and distress: a comparison between ethnic Norwegians and ethnic Pakistanis in Oslo, Norway

BACKGROUND

In the Norwegian context, higher mental distress has been reported for the non-Western immigrants compared to the ethnic Norwegians and Western immigrants. This high level of distress is often related to different socio-economic conditions in this group. No efforts have been made earlier to observe the impact of changed psychosocial conditions on the state of mental distress of these immigrant communities due to the migration process. Therefore, the objective of the study was to investigate the association between psychological distress and psychosocial factors among Pakistani immigrants and ethnic Norwegians in Oslo, and to investigate to what extent differences in mental health could be explained by psychosocial and socioeconomic conditions.

METHOD

Data was collected from questionnaires as a part of the Oslo Health Study 2000-2001. 13581 Norwegian born (attendance rate 46%) and 339 ethnic Pakistanis (attendance rate 38%) in the selected age groups participated. A 10-item version of Hopkins Symptom Checklist (HSCL) was used as a measure of psychological distress.

RESULTS

Pakistanis reported less education and lower employment rate than Norwegians (p < 0.005). The Pakistani immigrants also reported higher distress, mean HSCL score 1.53(1.48-1.59), compared to the ethnic Norwegians, HSCL score 1.30(1.29-1.30). The groups differed significantly (p < 0.005) with respect to social support and feeling of powerlessness, the Pakistanis reporting less support and more powerlessness. The expected difference in mean distress was reduced from 0.23 (0.19-0.29) to 0.07 (0.01-0.12) and 0.12 (0.07-0.18) when adjusted for socioeconomic and social support variables respectively. Adjusting for all these variables simultaneously, the difference in the distress level between the two groups was eliminated

CONCLUSION

Poor social support and economic conditions are important mediators of mental health among immigrants. The public health recommendations/interventions should deal with both the economic conditions and social support system of immigrant communities simultaneously.

Psychotic symptoms in the general population of England--a comparison of ethnic groups (The EMPIRIC study)

BACKGROUND

There is considerable evidence that incidence of schizophrenia and other psychoses varies across ethnic groups in the UK, with particularly high rates for people of African-Caribbean origin.

AIMS

The aims of this shady were to estimate in a community-based sample of people from ethnic minorities: 1) the prevalence of psychotic symptoms; and 2) risk factors for reporting psychotic symptoms.

METHOD

Face-to-face interviews were carried out with a probabilistic sample of 4281 adults from six ethnic groups living in the UK. Psychotic symptoms were measured using the psychosis screening questionnaire (PSQ).

RESULTS

There was a twofold higher rate of reporting psychotic symptoms on the PSQ in Black Caribbean people compared with Whites. Adjustment for demographic factors had little effect on this association.

CONCLUSION

Prevalence rates of psychotic symptoms were higher in people from ethnic minorities, but were not consistent with the much higher first contact rates for psychotic disorder reported previously, particularly in Black Caribbeans.

Psychiatric disorders and social characteristics among second-generation Moroccan migrants in Belgium: an age-and gender-controlled study conducted in a psychiatric emergency department

PURPOSE

Clinically, one of the most consistent clinical findings among migrant patients is an increase in the rate of psychosis. The aim of the present study was to confirm this finding in Belgium by comparing second-generation Moroccan migrant patients with Belgian patients, matched for the variables of age and gender.

SUBJECTS AND METHOD

We conducted a cross-sectional survey on 272 patients admitted in a psychiatric emergency unit during the year 1998. We used univariate and multivariate analyses to compare the two subgroups.

RESULTS

Multivariate analyses showed that migrant patients lived more often with their parental family and that they presented a higher rate of admission for psychotic disorders and a lower rate of employment.

DISCUSSION

Our findings add to the growing body of results showing increased incidence of psychosis among immigrants to European countries, but several factors have to be taken into account, particularly with regard to selection biases and differences in help-seeking behaviour and in family perception of the mental illness.

CONCLUSION

Our results are compatible with the hypothesis that unemployment is a contributing factor in the risk for psychosis among migrant groups. Further studies would be needed to better explain some of our results, particularly the role played by the families of migrant patients.

Culture and schizophrenia and other psychotic disorders

The comparative study of schizophrenia and related disorders across cultures has come a long way since Kraepelin advocated its cause, following his trip to Java at the beginning of the last century. The principal development since then has been the burgeoning of interest in the field, culminating in innovative and ambitious international collaborative research by the WHO. Despite reservations about covert ideology or about the more overt methodologic difficulties, the balance of evidence from these and similar studies suggests that: It is feasible to conduct such research despite the numerous hazards. There is a certain uniformity to the way schizophrenia presents globally; there are equally significant cultural differences. The outcome of schizophrenia appears to be better in developing, than developed cultures; reasons for this are far from clear, nevertheless, it can be safely assumed that culturally-determined processes, whether social or environmental, are partly responsible. Overall, the study of schizophrenia in different cultures has proved useful in establishing the pancultural and the culture-specific properties of this and related disorders.

A Jamaican psychiatrist evaluates diagnoses at a London psychiatric hospital

BACKGROUND

Authors have suggested that the high rate of schizophrenia reported for African-Caribbeans living in the UK is due to misdiagnosis by British psychiatrists.

AIMS

To compare the diagnoses made by a Black Jamaican psychiatrist with those of White British psychiatrists.

METHOD

All in-patients on four wards at the Maudsley hospital were approached for the study; 66 participated: 24 White, 29 Black African-Caribbeans and 13 Blacks from other countries of origin. F.W.H., a Black Jamaican psychiatrist, conducted his standard clinical assessment and performed the Present State Examination (PSE) on these patients. His diagnoses were compared with the case note diagnoses made by British psychiatrists, and with the PSE CATEGO diagnoses.

RESULTS

Of 29 African and African-Caribbean patients diagnosed with schizophrenia, the diagnoses of the British and the Jamaican psychiatrists agreed in 16 instances (55%) and disagreed in 13 (45%). Hence, interrater reliability was poor (kappa = 0.45). PSE CATEGO diagnosed a higher proportion of subjects as having schizophrenia than the Jamaican psychiatrist did (chi 2 = 3.74, P = 0.052).

CONCLUSIONS

Agreement between the Jamaican psychiatrist and his UK counterparts about which patients had schizophrenia was poor. PSE CATEGO may overestimate rates of schizophrenia.

Schizophrenia: a review of current research and thinking

Schizophrenia is the major mental illness of our time and causes serious disturbances for those with the condition as well as using up significant proportions of scarce health resources. This paper reviews the recent literature on advances in classification, aetiology, epidemiology and treatments. Methodological problems encountered in researching this condition are discussed. Advances in treatments offered for this condition have improved outcomes but whether the patient receives these treatments may depend on what local services are prepared to offer.

The new epidemiology of schizophrenia

A confluence of findings from different vantage points has led to renewed interest and direction in the epidemiology of schizophrenia. This article provides an overview of prevalence and incidence data, examining the validity of reported secular trends in the occurrence of schizophrenia. Advances in molecular genetics have uncovered new linkage on chromosomes 6, 8, and 22 and have suggested complex models, including anticipation, to explain the perpetuation of genetic transmission in the face of low fecundity. Neurotropic viruses and autoimmunity have emerged as pathoplastic mechanisms to explain recent intriguing epidemiologic associations in schizophrenia. Environmental risk factors are also important. With attention to particular risk factors (i.e., perinatal hypoxia), a preventative approach may be realistic for some forms of schizophrenia.

The 100-year epidemiology of schizophrenia

Since Kraepelin delineated dementia praecox as a disease entity construct, epidemiological studies conducted since the beginning of the century have produced remarkably consistent estimates of its prevalence, incidence and lifetime risk across various populations and geographic areas. A similar pattern emerged from the WHO ten-country study on first-contact incidence of schizophrenia. The diagnostic concept of dementia praecox originally used by Kraepelin and that of schizophrenia employed in the WHO studies were found to overlap extensively, indicating continuity over time. However, the findings of a similar incidence of schizophrenia in diverse populations and across time periods are unusual for a multifactorial disease and are compatible with at least two alternative interpretations that have different implications for the search for genetic and environmental causes of the disorder.

Increased rate of psychosis among African-Caribbeans in Britain is not due to an excess of pregnancy and birth complications

BACKGROUND

It has been suggested that the increased rate of psychotic illness among African-Caribbeans living in Britain is due to an excess of pregnancy and birth complications (PBCs).

METHOD

We therefore compared the frequency of PBCs in a group of White psychotic patients (n = 103) and a comparable group of patients of African-Caribbean origin (n = 61); the latter consisted of 30 first-generation (born in the Caribbean) and 31 second-generation (born in Britain) individuals.

RESULTS

White psychotic patients were more than twice as likely to have a history of PBCs as their African-Caribbean counterparts (odds ratio = 2.34, 95% confidence interval (CI) 0.88-6.47, P = 0.062). The same trend was observed among patients with a DSM-III diagnosis of schizophrenia (odds ratio = 1.65, 95% CI 0.56-4.97, P = 0.32). The rate of PBCs was similar among the first- and second-generation Caribbean psychotic patients.

CONCLUSIONS

The increased rate of psychotic illness that has been reported among the African-Caribbean population in Britain is not due to an increased prevalence of PBCs.

Psychopathology of white mentally ill immigrants to Jamaica

OBJECT

To test the hypothesis that white immigrants to a predominantly black country have a different pattern of psychopathology from the native population.

METHOD

The psychopathology (DSM III-R) of white immigrants to Jamaica seen in the author's private practice between 1979 and 1990 was compared with the psychopathology of a control sample of native Jamaicans matched with the immigrant sample for age, sex, and social class.

RESULTS

There was no statistical difference in the major diagnoses mood disorder (35%), anxiety states (27%), and schizophrenia (20%) between the immigrant and control groups. White immigrants to this black country did not develop schizophrenia at higher rates than the native born. White mentally ill immigrants to Jamaica move into social class positions at a significantly higher level (p < 0.005) than those of their parents with whom they grew up in their home country. This was significantly different (p < 0.005) from their Jamaican controls. Two case studies are presented to illustrate these findings.

CONCLUSIONS

The political/economic situation which exists in black postcolonial countries like Jamaica provides a protective social environment for white immigrants, which buffers them from the etiological conditions that engender schizophrenia in immigrants to other countries with predominantly white populations.

Do obstetric complications cause the earlier age at onset in male than female schizophrenics?

We compared the age at onset of 184 patients with functional psychoses with and without a history of obstetric complications (OCs) as defined by the scale of Lewis et al. (1989). OCs had no significant influence on the age at onset in those patients who had affective psychoses or were non-white. There were 73 white patients with a DSM-III-R diagnosis of schizophrenia. The mean age at onset of those 25 who had a history of at least one definite OC was 2.6 years earlier than that of the 48 patients with no history of OCs. This effect was entirely due to the male patients with histories of OCs who had, on average, a 3.5 years earlier age at onset. There were no gender differences in age at onset among schizophrenics without a history of OCs. We suggest that a subgroup of male patients with a history of OCs is responsible for the earlier age at onset in male compared to female schizophrenics.

Psychotic illness in ethnic minorities: clarification from the 1991 census

Age and sex-adjusted first admission rates for operationally-defined schizophrenia and other non-affective psychosis in different ethnic groups were calculated over the period 1988-1992 in a defined catchment area in South London. Standardized rates for schizophrenia, corrected for age- and gender-related under-reporting in the 1991 census and a 20% underestimate of the size of the ethnic minority populations in the area, were not only higher in the Afro-Caribbean group (SMR: 3.1; 95% C1:2.0-4.7), but also in the African group (SMR: 4.2; 95% C1: 2.8-6.2). It was further found that higher rates were not specific to schizophrenia. These findings suggest that some common factor associated with ethnic minority membership is important in producing an excess of psychotic illness.

Male Afro-Caribbean patients admitted to Rampton Hospital between 1977 and 1986--a control study

All Afro-Caribbean patients admitted to the Mental Illness Division of Rampton Hospital (a Special Hospital) between 1977 and 1986 and a randomly selected control cohort of Non Afro-Caribbean patients admitted in the same period, were compared on a variety of sociodemographic, psychiatric, criminological, treatment and outcome variables. Significantly, fewer of the Afro-Caribbean patients attracted the legal classification of Psychopathic Disorder. Detailed analysis was thus restricted to mentally ill patients in the two ethnic groupings. Similarities outweighed differences. There was no difference between the groups in terms of index offence, previous custodial sentence, in-patient psychiatric admission (including previous Special Hospital admission), admission source, Mental Health Act section, length of admission (including readmission) to Special Hospitals, likelihood of discharge or place to which discharged. Medication history in Special Hospitals was similar at one year and three years after admission. Afro-Caribbean patients had a lower incidence of childhood institutional care, a decreased likelihood of a previous supervision order, an increased likelihood of a previous Court appearance and received higher doses of antipsychotic medication four weeks after admission to Special Hospital.

Inner london collaborative audit of admission in two health districts. III: Reasons for acute admission to psychiatric wards

BACKGROUND

In this series, rates of admission and daily bed use in south Southwark were 30% higher than in Hammersmith & Fulham, principally because of a higher rate of admission for affective disorders. Factors associated with compulsory admission did not differ between the districts. This final paper examines the severity of symptoms, the reasons given for admission and factors relevant to the judgement to admit, in order to test the hypothesis that more resources mean better service.

METHOD

Sampling and data collection methods were described in the first paper.

RESULTS

In both districts, major reasons for admission were self-neglect and risk of self-harm, poor adaptive functioning, and poor acceptance of medication. In south Southwark, a group of patients had affective disorders and less severe symptoms but a stated risk of suicide. Rates for, and severity of, schizophrenia were similar in the two districts. Social and preventive reasons for admission were given more frequently in south Southwark, where patients had more often been in contact with services before admission. Staff there, but not in Hammersmith & Fulham, suggested that many could have benefited from alternative forms of residential care.

CONCLUSIONS

A 'buffer' of hospital beds in south Southwark may have allowed a more acceptable service, particularly for affective disorders. The possibility that this buffer could be replaced by a wider range of residential accommodation, including hostels away from the District General Hospital, is discussed. Ten recommendations are listed.

Incidence of psychotic illness in London: comparison of ethnic groups

OBJECTIVE

To compare annual incidences of psychosis in people from different ethnic groups as defined in the 1991 census.

SETTING

Catchment area of district psychiatric hospital.

DESIGN

All people aged 16 to 54 years who made contact with a wide range of community and hospital services between 1 July 1991 and 30 June 1992 were screened for psychotic symptoms. Patients with such symptoms were interviewed face to face to collect information on demography, ethnic group, psychiatric history and symptoms, drug use, and how care had been sought. A key informant, usually a close relative, was also interviewed.

MAIN OUTCOME MEASURES

Age standardised incidence of schizophrenia and non-affective psychosis according to the ninth edition of the International Classification of Diseases in each ethnic group.

RESULTS

Ninety three patients took part, of whom 38 were assigned a certain or very likely diagnosis of schizophrenia (15 in white population, 14 in black, seven in Asian, and two in others). The age standardised annual incidence of schizophrenia was 2.2 (95% confidence interval 1.5 to 2.9) per 10,000 of the population. The incidence ratio for schizophrenia in all ethnic minority groups compared with the white population was 3.6 (1.9 to 7.1); the corresponding figure for non-affective psychosis was 3.7 (2.2 to 6.2).

CONCLUSIONS

Raised incidences of schizophrenia were not specific to the African Caribbeans, which suggests that the current focus on schizophrenia in this population is misleading. Members of all ethnic minority groups were more likely to develop a psychosis but not necessarily schizophrenia. The personal and social pressures of belonging to any ethnic minority group in Britain are important determinants in the excess of psychotic disorders found.

Can environmental factors explain the epidemiology of schizophrenia in immigrant groups?

Recent evidence suggests that high rates of schizophrenia in first- and second-generation immigrants could be due to exposure to environmental factors such as viral infections in the host country. These findings are discussed alongside parallel data relating to other diseases such as multiple sclerosis and diabetes mellitus. It is argued that in each case the interaction between the environmental agent and constitutional factors related to the immune system need to be considered.

A negative association of schizophrenia with an allele of the HLA DQB1 gene among African-Americans

Using polymorphisms of the human leukocyte antigen (HLA) DQB1 gene, a case-control study was conducted in a group of patients with schizophrenia (DSM-III, n = 58) and psychiatrically normal controls matched for ethnicity (n = 72), living in the same geographical area. A significant negative association of allele HLA DQB1*0602 with schizophrenia was present among African-Americans (odds ratio 0.19), but could not be detected in Caucasians.