Our main finding was that perceived discrimination was associated with more severe positive and depression/affective symptoms among immigrants with psychosis. In contrast, perceived discrimination was not significantly associated with the severity of negative, cognitive, or excitement symptoms. Perceived discrimination had a partial mediating effect on the severity of positive and depression/anxiety symptoms in African immigrants. Perceived discrimination also has a strong independent effect on the severity of positive and depression/anxiety symptoms even after controlling for diagnostic group, immigrant generation, and geographic origins.
Our results are in accord with earlier findings demonstrating an association between discrimination and delusional ideation (a positive symptom) [16
]. Furthermore, a recent meta-analysis found that discrimination, independent of ethnicity, was related to poor mental health, including a higher incidence of depressive symptoms [12
]. This same meta-analysis also found a clear relationship between discrimination and measures of physical stress, such as elevated blood pressure, heart rate, and cortisol secretion. This may partly explain the association between perceived discrimination and somatic concerns, anxiety, and tension that were all sub-items of the depression/anxiety factor used in our study. A recent study of a large sample of Puerto Ricans in the USA concluded that depressive symptoms were a mediator of the effect of perceived discrimination on a number of somatic conditions [43
]. We have previously shown that immigrants who have migrated from the Southern to the Northern Hemispheres and patients with psychotic disorders in general are more prone to vitamin D deficiency, another factor which is associated with depressive symptoms [44
]. Including levels of vitamin D might have enhanced the predictive value of our model, but unfortunately we did not have access to vitamin D measures in all participating patients.
We found that immigrants from outside Europe had more severe symptoms than immigrants from Europe. Early research from the beginning of the 19th century reported increased rates of schizophrenia among immigrants from Britain and Continental Europe to Canada, and among Norwegian immigrants to the USA [45
]. Seeman [6
] suggested that these immigrant groups, although not visible minorities, did stand out in their new country because of language difficulties, higher unemployment, and a history of deprivation. Perception of discrimination may engender feelings of alienation among visible minorities that in turn exacerbate symptoms. Immigrants from Europe may better integrate with the majority (Caucasian) culture, while both FGIs and SGIs from Africa and Asia are more visible and must adapt to greater cultural barriers [47
]. In fact, we found that perceived discrimination was a mediator for the influence of African immigrant status on the severity of positive and depression/anxiety symptoms. These findings are of particular importance considering that the highest relative risk of developing psychotic disorders in immigrant groups was found among those migrants from areas where the majority of the population is black [1
Based on these results, we suggest that discrimination can be an important environmental stressor leading to the development and escalation of both depression/anxiety and positive psychotic symptoms in patients with psychotic disorders, and may help explain the distinct psychopathology profiles reported in different ethnic minorities. The experience of deprivation of resources and rewards based on visible minority status may lead to feelings of hopelessness and an external locus of control, both of which are psychological mechanisms associated with depression [48
]. Visible minority status may also enhance alienation and in some cases lead to actual persecution. Cultural differences can result in miscommunication between the minority and majority populations. For individuals predisposed to psychosis, these experiences can lead to enhanced suspiciousness and to psychotic episodes. This conclusion is supported by findings demonstrating that peer victimization in childhood increased the risk for psychotic symptoms, independent of prior psychopathology, family adversity, or IQ [49
], and supports the hypothesis that experiences of social defeat are important in the etiology of schizophrenia [13
It is possible that individuals who are prone to psychosis or suffering from paranoid ideation are likely to perceive neutral or ambiguous situations as discriminatory. As our study was cross-sectional, we were unable to assess the direction of the association between perceived discrimination and symptom profiles. However, a meta-analysis of 110 studies found that perceived discrimination was significantly related to negative mental health outcomes and that 12 experimental studies assessing causality found that perceived discrimination can indeed cause an increase in both physical and psychological stress responses in healthy populations, strongly supporting the causative role of discrimination [12
]. Longitudinal and controlled experimental studies are needed to assess the direction of associations between perceived discrimination and symptom severity in immigrants with psychosis.
Strengths and Limitations
Our study included a well-documented clinical sample of patients with psychotic disorders. Patients were recruited from a public health care system providing equal treatment services to all groups with extensive experience in treating patients from different cultures. The organization of the Norwegian public health care system thus ensures more representative recruitment than more socioeconomically segregated systems. Our final sample also mirrored the true demographics of the Oslo immigrant population, with the exception of a higher proportion of SGIs (and fewer FGIs). This could be a consequence of the language exclusion criterion, where we required patients to have adequate Scandinavian language skills. It is expected that more SGIs are competent in Norwegian, but this may have excluded FGI patients with poor language skills.
An important consideration in cross-cultural studies of psychopathology is the validity of the assessment tools. The assessment personnel in our group were trained to use the SCID-I for diagnostic purposes by watching training videos that including patients from different ethnic and cultural backgrounds. The instrument used to assess symptom severity (PANSS) was originally developed in an inter-ethnic population, thus strengthening its cultural validity. Diagnostic evaluations and symptom assessments were based on face to face interviews rather than patient journals, databases, or surveys. However, it is unavoidable that the assessor is aware of each patient's ethnicity, and this could influence diagnosis. In addition, the ethnic sub-groups were small, possibly limiting the generalization of our findings. The cross-sectional design of this study prevents us from making causal inferences, and we cannot make any inferences of risk.