In this study we used a large national survey to examine patterns of lifetime risk for mood and anxiety disorders associated with US-nativity and age at immigration across a more diverse set of immigrant groups than has been examined in any previous study. While previous studies have suggested that an immigrant paradox exists for mental health in the USA, i.e. that immigrants have lower risk than would be predicted by their socio-economic position, our findings suggest that the immigrant advantage in risk for mood and anxiety disorders is limited in several respects. First, among some groups immigrants are not at lower risk for these disorders than the US-born. Second, among groups in which immigrants have an advantage with respect to the US-born in lifetime risk for mood and anxiety disorders, this advantage is generally limited to those immigrants who arrived in the USA as adolescents or adults, i.e. older than the age of 12 years. Two exceptions to this second pattern are noted below.
Comparison of our results with previous studies summarized in shows that our results are consistent with prior studies that have compared immigrants with US-born when those prior studies defined groups as we have done here. Specifically, previous studies of Mexican-Americans (Grant et al. 2004
) and African-Americans (Williams et al. 2007
) have found lower risk among immigrants relative to the US-born and studies of Puerto Ricans and Cubans (Alegría et al. 2008
) have found no differences between the Island-born and mainland born. These consistencies across studies strengthen our confidence in these results. This is the first study to distinguish people of Western European and Eastern European origin, to examine people of Central or South American origin, and to examine age at immigration across this broad range of immigrant groups.
Groups without nativity differences in risk for disorders
We found no evidence of an association of lifetime risk for mood and anxiety disorders with US-nativity and age at immigration among Hispanics from Puerto Rico or non-Hispanic Whites from Western Europe. In both cases, immigrants have equally high levels of risk as the US-born, regardless of the age at which they arrived in the USA. Previous studies of people of Puerto Rican origin in the USA have also found no association between US-nativity and risk for psychiatric disorder (Ortega et al. 2000
; Alegría et al. 2008
), and epidemiological evidence from Puerto Rico also suggests that risk for disorder is equally high there as among the US general population (Canino et al. 1987
Previous studies have included people of Western European origin in the broader category of non-Hispanic White (Grant et al. 2004
; Alegria et al. 2006
; Breslau et al. 2007b
), which in the USA includes people from Eastern Europe and the Middle East as well as people of European ancestry from other areas of the world. Our results suggest that people of Western European origin are an important exception to the pattern of lower risk among immigrants relative to the US-born that has been reported in those studies. There are no studies of mood and anxiety disorders in samples representative of the sending population of Western Europe. Published data from the European Study of the Epidemiology of Mental Disorders (ESEMeD) study, which included six Western European countries (France, Spain, The Netherlands, Italy, Germany and Belgium) found lower lifetime prevalence of mood (14.0%) and anxiety (13.6%) disorders compared with our findings (Alonso et al. 2004
). However that study did not include England or Ireland, the two largest sources of immigrants to the USA in Western Europe.
It is important to note that these two groups, Puerto Ricans and Western Europeans, though similar in having high levels of risk regardless of place of birth or age at immigration, are very different with respect to cultural backgrounds, levels of development in country of origin and motivation for immigration.
Groups with lower risks of disorders among immigrants
In three groups from three different world regions –Hispanics from Mexico, non-Hispanic Whites from Eastern Europe, and non-Hispanic Blacks from Africa or the Caribbean – we found a very similar pattern of differences in the risk for mood and anxiety disorders. In each of these groups, there was no difference in lifetime risk between immigrants who arrived in the USA at the age of 13 years or younger and the US-born, but lower risk among immigrants who arrived after the age of 13 years compared with the US-born. This pattern is identical to that found in a previous study of people of Asian origin from this survey (Breslau & Chang, 2006
). In all four of these groups, the association between risk for mood and anxiety disorders is due to differences between people who spent their early childhood in the USA and those who spent their early childhood outside of the USA. This pattern strongly suggests that factors present in early development account for this association (Breslau et al. 2007b
; Takeuchi et al. 2007a
). Of these three groups, comparable studies are available only for Mexico, where studies have found lower lifetime prevalence for mood (9.1%) and anxiety (14.3%) disorders than in the USA (Medina-Mora et al. 2003
Hispanics of Cuban or South or Central American origin follow neither of the above patterns. Among the group of Cuban origin, there were no significant associations between lifetime risk and US-nativity. However, Cubans differed from the Western European and Puerto Rican groups discussed above because there is some evidence that immigrants who arrived in the USA at the age of 13 years or older were at lower risk for mood disorders than immigrants who arrived at the age of 12 years or younger. These differences do not reach statistical significance. Among those from South or Central America, there was no association between US-nativity and risk for mood disorders, but immigrants had lower risk for anxiety disorders than the US-born regardless of the age at which they arrived in the USA.
Differences between immigrants and the US-born in mental health and general health status might be explained by a number of processes. Immigrants and their US-born descendants also differ on a wide range of behavioral risk factors for adult health problems (Abraido-Lanza et al. 2005
). Among these behavioral risk factors associated with US-nativity, use of alcohol (Johnson et al. 2002
), nicotine (Acevedo-Garcia et al. 2005
) and other drugs (Blake et al. 2001
) may be factors in subsequent mood and anxiety disorders (Swendsen & Merikangas, 2000
). However, the results of this and other studies (Breslau et al. 2007b
) suggest that changes in risk for mood and anxiety disorders occur more rapidly than changes in these behavioral risk factors. There is evidence that immigrants who arrived in the USA as children, who our results suggest have an equally high risk for mood and anxiety disorders as the US-born, are less likely to use substances than the US-born. A recent report by Alegria and colleagues suggests that among Puerto Ricans, those born in Puerto Rico are not at lower risk for mood and anxiety disorders despite lower risk for substance-use disorders compared with those born in mainland USA (Alegría et al. 2008
Another potential explanation that is also inconsistent with our findings is that stressors that are specific to the immigration process, i.e. acculturative stress, account for increasing risk for disorder (Alegria et al. 2007b
). Acculturative stresses, resulting from the disconnection from one’s culture of origin and struggle to accommodate a strange and potentially hostile environment in the host country (Rogler et al. 1991
), are more extreme among immigrants who arrived in the USA as adults. Immigrants who are older at arrival have already developed social networks and cultural orientations in their country of origin while immigrants who arrived as children experience their primary socialization in the USA. However, the pattern of risk for mood and anxiety disorders does not follow the pattern that one would predict if acculturative stress were the primary cause of increasing risk; it is the younger immigrants and not the older immigrants who experience higher risk for disorder.
Similarly, our results are not consistent with a protective effect of immigrant cultural practices on risk for mood and anxiety disorders. Cultural practices that change across generations as immigrant groups assimilate to the USA, such as strong extended kinship networks, have been suggested as explanations for relatively good physical health status and low mortality among some immigrant and minority groups (Singh & Miller, 2004
; Markides & Eschbach, 2005
). If these factors were also protective with respect to mood and anxiety disorders we would predict lower risk among immigrants who arrived as children, who are more likely to live in immigrant communities, compared with the US-born. Our findings do not confirm this prediction.
An alternative hypothesis is that differences associated with US-nativity arise from cross-national differences in disposition to mood and anxiety disorder acquired in childhood. Our results are consistent with this model in two important respects. First, low risk is generally restricted to immigrants who spent their early life outside of the USA. People who spent their early life in the USA appear to have similar levels of risk, regardless of place of birth. Second, the same pattern of risk associated with US-nativity occurs among groups from vastly different ancestral origins (Eastern Europe, Mexico, Africa/Caribbean) and from different ethnic groups in the USA (Hispanic, non- Hispanic Black and non-Hispanic White). The fact that the same pattern was observed in an earlier study of Asian-Americans (Breslau & Chang, 2006
) further strengthens this evidence. The fact that immigrants who arrived as children in the USA from these vastly different backgrounds acquire the same high level of risk for mood and anxiety disorder as the US-born population suggests developmental pathways that are common to enculturation of both immigrants and natives rather than a distinct set of pathways characteristic of immigrants (Sam, 2006
It is important to note the difference between this explanation for differences in risk associated with US-nativity and the ‘healthy migrant hypothesis’, which has also been suggested (Grant et al. 2004
; Alegria et al. 2006
). Differences between immigrants and the US-born may be due to cross-national differences whether or not immigrants differ in risk from the general populations in their countries of origin. Studies with comparable data collected in both sending and receiving countries are needed to assess the healthy migrant hypothesis.
The pattern of variation in risk we found could be due in part to the exclusion from the sample of individuals who could speak neither English nor Spanish. These individuals are most likely to be immigrants who arrived in the USA as adults. If there were higher prevalence of disorder among individuals who spoke neither English nor Spanish, we would underestimate the prevalence of disorder in that group. However, evidence from studies that interviewed respondents in a wider variety of languages, particularly Asian languages, suggests that individuals who are not proficient speakers of English or Spanish have equal lifetime risk for psychiatric disorders as those who are proficient speakers of English or Spanish (Takeuchi et al. 2007b
). These patterns have not been investigated among speakers of European languages (other than Spanish).
The sample sizes are smallest for immigrants who arrived prior to the age of 13 years. It is possible that the finding of no difference in risk between the immigrants who arrived prior to the age of 13 years and the US-born is due to the limited power we have to detect differences between these two groups. We cannot rule out the possibility that a larger study would find significant differences. However, among the groups where differences between the US-born and immigrants were limited to those who arrived at the age of 13 years or older, we found that the two ORs comparing the age at immigration subgroups with the US-born were statistically different from each other (results not shown).
Data in this study were collected at a single point in time and are affected by problems in recall of psychiatric symptoms across the lifespan. Evidence from methodological studies suggests that problems in recall are likely to result in underestimates of lifetime prevalence of disorder because more people fail to recall symptoms than mis-remember symptoms that did not occur. Problems in recall would lead to bias in the current study if they were systematically related to US-nativity, but this possibility has not been examined in methodological studies. In the one longitudinal study that compared retrospective reports of depression with prior assessments, respondents were likely to under-report past symptoms, but associations between depression and risk factors did not differ meaningfully across the two ascertainment methods (Wells & Horwood, 2004
Psychiatric diagnoses were made by lay interviewers and the chance corrected agreement (κ coefficient) with clinician interviews for some disorders was in the fair to moderate range, as reported above. To examine whether our results may have been affected by low κ we repeated the analysis reported above for major depression, the disorder with the highest κ. We found the same pattern of results for major depression as for the mood disorders as a group (results available on request).
We have offered some comparisons of our results with epidemiological studies of psychiatric disorders conducted in immigrant-sending populations. While suggestive, these comparisons do not adjust for the many factors that might lead to differences between immigrants in the USA and the general population in their country of origin. None of these studies used the same survey instrument, and none of the comparisons adjusted for factors that might predict both immigration and lifetime risk for psychiatric disorder such as age, sex and socio-economic status. Future studies based on samples interviewed with consistent methods in both sending and receiving countries are needed to evaluate the impact of immigration on risk for psychiatric disorders.
The finding in this study regarding differences in risk associated with US-nativity and age at immigration do not imply that migration to the USA is not associated with increases in risk among those who arrived in the USA as adults. There is evidence that longer duration of residence in the USA is associated with higher risk of disorder among immigrants relative to the US-born (Vega et al. 1998
; Alderete et al. 2000
; Breslau & Chang, 2006
; Alegria et al. 2007c
; Breslau et al. 2007b
; Takeuchi et al. 2007a
). However, variations in the pattern of risk associated with duration of residence across these seven immigrant groups have not been investigated. Studies of the impact of immigration to the USA should focus on those who arrived in the USA as adults. The most valuable studies will be those that can compare immigrants with the populations from which they emigrated, controlling for other predictors of migration and mental health (Breslau et al. 2007a