Several limitations of the data should be considered in interpreting these results. First, the AA population in the US is heterogeneous with respect to country of origin, motivation for immigrating to the US, pre-migration culture and socioeconomic status, and achieved social status within the US [14
]. There may be AA groups among whom differences in psychiatric morbidity between immigrants and natives do not follow the pattern identified here. In particular there is evidence that immigrants from Southeast Asia, who arrived in the US as refugees, experience high levels of poverty as well as extremely high prevalence of depression and post-traumatic stress disorder [19
]. Our findings in this national sample that consists mostly of ‘voluntary’ migrants may not generalize to involuntary migrants, such as refugees, who migrate under very different circumstances and though numerically small, experience substantially different patterns of morbidity and have large needs for targeted services.
Due to the small samples of AAs from specific countries, our ability to examine within group differences was limited to individuals of Chinese, Filipino, Japanese and Korean origin. In separate analyses within these four groups (results not shown) there was no class of disorder for which risk among the foreign-born was significantly higher than risk among the US-born. Risk was lower among the foreign-born relative to the US-born in every case, with one exception: in the Chinese subsample risk for mood disorders was non-significantly elevated among the foreign-born relative to the US-born (OR = 1.32, 95 CI (0.48, 3.65)). Studies with larger samples of specific subgroups of Asian-Americans are needed to thoroughly examine the extent to which the patterns identified in this survey are consistent across groups.
Second, the results may also be affected by the restriction of the sample to respondents who could be interviewed in English or Spanish, a criterion that effectively skewed the sample towards more acculturated AAs. Studies of Hispanic immigrants have found that the lifetime prevalence of psychiatric disorders is likely to be higher among more acculturated immigrants [7
]. While this general trend was not replicated in the CAPES [13
], we recognize that our prevalence estimates may actually overestimate the level of risk due to the exclusion of AAs with limited English-language skills. Despite this possibility, it is notable that we still find significantly lower risk among immigrants in comparison with native-born AAs.
Third, foreign-born AAs may be less familiar than the US-Born with American idioms of mental health and therefore respond differently to survey questions used to assess psychiatric disorders [21
]. Although some methodological investigations of the cultural validity of standardized diagnostic assessments have been conducted among American Indians for example [13
], similar studies that compare immigrants and natives with respect to epidemiological assessments of psychiatric disorders have not yet been undertaken with AA populations.
Similar to patterns found among Hispanics and Non-Hispanic Whites in the United States [6
], foreign-born AAs had significantly lower risk for all classes of psychiatric disorders than US-born AAs. This finding suggests that, with the exception of refugee groups noted above, social or cultural conditions of life in the United States may contribute to psychiatric morbidity regardless of the national or ethnic origin of immigrant groups or their experience of socioeconomic disadvantage as they become incorporated into American society. This pattern, moreover, is not specific to the US, but has also been found for depression among immigrants to the UK [35
] and for psychotic disorders among immigrants to Europe [36
] and Australia [37
More detailed specification of differences between immigrants and natives revealed patterns that are informative with respect to potential causal pathways. First, differences between immigrants and natives depend on the age at which immigrants arrive in the US, suggesting that the timing of exposure to American society with respect to developmental stage plays an important role in determining lifetime risk for psychiatric disorder. Immigrants who arrived as children (age 13 or earlier) were at higher risk for all classes of disorder than immigrants who arrived later in life. In fact, for mood and anxiety disorders, immigrants who arrived as children did not differ from US-born AAs. This suggests that factors that protect adult immigrants from mood and anxiety disorders are not transmitted to their children who arrive in the US prior to adolescence.
The pattern of risk across ages at immigration was different for substance use disorders. Foreign-born AAs who arrived in the US as children had lower risk for substance use disorders than US-born AAs, but higher risk than foreign-born AAs who arrived later in life. This finding is consistent with the finding from other surveys that immigrant adolescents are at lower risk for substance use and misuse than native born adolescents [38
]. The explanation for this pattern, and the difference between substance use disorders and other psychiatric disorders, is unclear. Children in immigrant families may be protected from substance use because of the orientation of their families towards educational attainment and social mobility [40
] or because of the lack of social networks that provide opportunities to use substances. These factors would not have the same effect on mood and anxiety disorders, the antecedents of which are not under conscious control.
Second, risk for first onset of disorder changed over time among the foreign-born in a similar pattern for all classes of disorder. In the years prior to arrival in the US, the foreign-born had lower risk for all disorder classes. It is important to note that this finding does not imply selective migration, i.e., that immigrants are more or less likely to have psychiatric disorders than their compatriots who do not immigration. Cross-national studies have found lower risk for psychiatric disorders in Asian countries [41
]. Thus if the foreign-born AAs in the US experienced the same level of risk as their compatriots they would be at lower risk than the US-born. In order to directly examine the selective migration hypothesis, studies which apply consistent methods in assessing risk among immigrant populations and their countries of origin are needed.
After arrival in the US, risk of first onset increased among the foreign-born relative to the US-born to the extent that there were no significant differences between these groups for any class of disorder after 15 years of residence in the US. No difference in this pattern was found between early and late immigrants (results not shown). By examining first onsets, this analysis extends previous studies which have found an association between duration of residence and lifetime or current prevalence of substance use or psychiatric disorders [5
]. The pace of change in risk for first onset differed for each class of disorders. The change was fastest for mood disorders, which is consistent with the finding in the CAPES that risk for onset of disorder was high in years immediately following immigration [25
]. For anxiety and substance use disorders, however, the change was drawn out over a longer period of time. The finding that this change was slowest for substance use disorders may reflect the same underlying process noted above; the etiological mechanisms for substance use disorders involve overt and identifiable behaviors, are thus more affected by conscious and explicit social sanctions, and are therefore more resistant to change.
Taken together, these findings suggest that both the developmental timing and the duration of experience in the United States contribute to increases in risk for psychiatric disorders among AAs as they adapt to American society. Furthermore, this pattern of results is consistent with roles for both acculturative stress and socialization to the US [25
] as etiological processes underlying this change. The role of acculturative stress is most likely to be related to increases in risk for first onset of disorder that we observed occurring shortly after arrival in the US. However, it is important to note in this regard that risk among the foreign-born did not exceed that of the US-born AAs in any time period. On the other hand, the role of early socialization, i.e., factors shared by foreign-born and US-born AAs, is suggested by the finding of higher risk among those immigrants who arrived in the US prior to adolescence.
These findings also have important clinical implications. First, our finding that risk for first onset of mood and anxiety disorders rises among the foreign-born shortly after their arrival in the US, indicates that though foreign-birth is a protective factor, those of foreign birth are not less likely to develop disorders while in the US. This finding underlines the needs for research and clinical training that aims to address the distinct language and cultural needs of foreign-born AAs. Second, the finding that risk for psychiatric disorders increases across generations as AA groups settle in the United States implies that current estimates of need for mental health services in these groups are likely to underestimate future needs as the US-born AA population grows.