Consistent with previous national surveys in the US, data from the NCS-R indicate that Hispanics and Non-Hispanic Blacks have lower lifetime risk of psychiatric disorders than Non-Hispanic Whites (Breslau et al., 2005
). This finding suggests the need to investigate potential protective factors that might explain the advantage that race-ethnic minority groups enjoy despite the social disadvantages they experience. Ethnic identification (Herd & Grube, 1996
; Mossakowski, 2003
) and religious participation (Ellison et al., 2001
; Lee & Newberg, 2005
; Varon & Riley, 1999
; Wallace & Forman, 1998
) have been suggested as protective factors that might explain lower lifetime risk for disorder among race-ethnic minorities. However, cultural and social factors that might be related to risk for psychiatric disorder are complex and have undergone significant changes in recent decades.
As noted in the introduction, our goal in this analysis was to advance the examination of suspected protective factors by investigating variation in race-ethnic differences across specific disorders, age of onset of disorders and subgroups of the population defined by cohort and education. The key findings of this analysis are: 1) Lower lifetime risk among race-ethnic minority groups relative to Non-Hispanic Whites are attributable to a small number of common disorders; 2) Lower lifetime risk among both Hispanics and Non-Hispanic Blacks relative to Non-Hispanic Whites begins in childhood (i.e. prior to age 10); 3) Differences in lifetime risk favoring minorities are more pervasive in the younger cohort (i.e. born circa 1958 or more recently); 4) Variation in race-ethnic differences across levels of education is sporadic and, where it occurs, it shows that lower lifetime risk in members of minority groups is more pronounced at lower levels of education (i.e. parent or respondent had less than high school education).
Lower risk for mood and anxiety disorders among both minority groups was accounted for by 5 disorders, major depression, dysthymia, GAD, social phobia, and panic disorder. These disorders fall within a set of ‘internalizing’ disorders, which cluster together in factor analyses, suggesting that they may share etiologic pathways (Kendler et al., 2003
; Krueger, 1999
). The finding that these disorders vary together in lifetime risk across race-ethnic groups suggests the presence of common protective factors across disorders for both minority groups. This possibility would be further supported if future analyses show that patterns of comorbidity among these disorders are similar across race-ethnic groups. With respect to substance use and impulse control disorders, the group of externalizing disorders which factor analyses suggest share etiologic processes (Kendler et al., 2003
; Krueger, 1999
), differences are not consistent among race-ethnic groups and across disorders, suggesting that the explanation for the observed differences are more complex.
The finding that race/ethnic differences emerge in childhood strongly suggests that the search for causes should focus on factors present in the early life environment. A focus on childhood is a particularly important consideration for studies of religious participation and ethnic identification. These factors are measured in adults, but may also reflect the cultural contexts in which children are socialized, rather than the direct effect of religious participation on adult experience.
We found that for Hispanics, differences in lifetime risk relative to Non-Hispanic Whites varied significantly across birth cohorts for all classes of disorder, and that the phenomenon of lower lifetime risk of disorders was specific to the younger cohort. For Non-Hispanic Blacks, a similar trend was found for substance use disorders. It is unclear that the protective factors suggested in the literature, ethnic identification and religious participation have followed a similar historical trajectory. There is no evidence that relative rates of religious participation
across groups have changed, but there is evidence that religious affiliations
within both minority groups have shifted toward conservative protestant groups that tend to promote abstention from alcohol (Hunt, 1999
; Sherkat, 2002
). The role of religion could be further elucidated if future studies examine whether observed historical changes in race-ethnic differences in risk of disorder are related to contemporaneous changes in specific aspects of religiosity. Future studies should also examine historical changes in patterns of immigration (Portes & Zhou, 2003
), educational achievement (Kao & Thompson, 2003
) and income (Levy, 1998
) across minority groups.
Analysis of variation in race-ethnic differences across levels of SES, using parental and respondent education as indicators, contradict the ‘double jeopardy’ theory, which would predict that low SES minorities would have the highest levels of risk because of the combined effect of socioeconomic and race-ethnic disadvantage. Where variation in race-ethnic differences in lifetime risk was found, the pattern was consistent with predictions of the ‘declining returns’ theory, which predicts that minority groups enjoy fewer of the health improvements that come with higher socioeconomic status. This pattern is consistent with research on Hispanics which found that Hispanic enclave communities offer social resources to their members that may have a salutary impact on health (Eschbach et al., 2004
; Portes & Zhou, 2003
; Sanders, 2002
The findings should be interpreted in light of several limitations. First, the assessment of lifetime risk for psychiatric disorders depends on the accuracy of lifetime recall of psychiatric symptoms. As mentioned in the methods section above, the WMH-CIDI included question sequences found in experimental research to improve recall of life events in survey research. There is no evidence that recall of psychiatric symptoms is differential across race-ethnic groups.
Second, differential non-response across race/ethnic groups may have led to underestimation of lifetime disorders among minority groups (US Department of Health and Human Services, 2001
). To minimize the impact of non-response bias in this survey, a non-respondent survey was carried out in which a representative sub-sample of initial non-respondents was administered a brief telephone survey that collected screening information about anxiety, mood, impulse-control, and substance disorders (Kessler et al., 2004b
). Results were used to weight the main survey data to adjust for any differential under-representation of disorders on the basis of race-ethnicity as well as other socio-demographic factors. In addition, missing data on parental education, a problem that was more common for minorities than for Non-Hispanic Whites, were imputed based on information on parental occupation. Results did not change meaningfully when observations with missing values were removed from the analysis, but it remains possible that residual bias remains that might limit the generalizability of the results reported here.
Third, cultural differences may lead members of different race/ethnic groups to respond differently to the same survey questions regarding their psychiatric history despite similar levels of morbidity (Rogler, 1999
; Rogler et al., 2001
). Psychometric studies of differential item functioning examining distress scales have found some differences along these lines across race/ethic groups. However, these differences generally overestimated levels of distress of minority groups and were attributable to items related to positive mental health (Iwata & Buka, 2002
). Positive mental health items are not used to assess disorders in this study. Reporting of psychiatric symptoms might also be influenced by the race-ethnicity of the interviewers. Since the finding of lower lifetime risk among minority groups is consistent across studies using different structured diagnostic instruments, e.g., the DIS (Somervell et al., 1989
; Weissman et al., 1991
), the UM-CIDI (Kessler et al., 1994
) and the WMH-CIDI (Kessler et al., 2005
), methodological studies of differential validity across race/ethnic groups should focus on methods shared by these instruments.
We have focused on race/ethnic differences in lifetime risk because of the counterintuitive finding of lower lifetime risk among disadvantaged groups. However, this finding of lower lifetime risk does not imply that disadvantaged groups suffer a lower overall burden of psychiatric morbidity. Our previous work suggests that the advantage of reduced lifetime risk is offset by the disadvantage of an increased risk for persistence among members of minority groups who become ill (Breslau et al., 2005
). Assessment of the aggregate public health implications of race/ethnic differences in psychiatric morbidity, therefore, will require comparisons that consider multiple aspects of the course of disorders, including persistence as well as severity and disability.