This study has examined patterns of co-occurring alcohol, drug, and non-substance use disorders in a national sample of Latino adults. Similar to the results of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) (Smith et al, 2006
) our results point toward important differences in patterns and prevalence rates among Latinos compared to other U.S. ethnic groups. Overall lifetime prevalence rates of dual diagnoses are nearly 4 times higher in the U.S. general population than in the Latino population living in the U.S., about 27% vs. 7% for the NCS study (Kessler et al, 1994
) and about 21.6% vs. 7% in the most recent NESARC study (Conway, Compton, Stinson & Grant, 2006
). Most of the difference between the NLAAS data and the other two US epidemiologic studies is accounted for by the far lower rates of dual diagnoses among immigrants and women (Kessler et al., 1994
). Although caution should be exercised in comparing lifetime with 12 month rates of disorder, the NESARC data showed similar results to ours insofar as the Latino groups had significantly lower dual diagnoses rates as compared to non Latino whites of substance use disorders co-occurring with depressive disorders and anxiety disorders (Smith et al, 2006
). These results have important implications for research about patterns of behavioral disorders in the context of immigration and age-sex demographic trends in subsequent U.S. born generations, as illustrated by the findings of sequential increases in substance disorder rates in U.S. born Latinos. US born Latino women appear to benefit from retention of protective cultural norms that partially offset the effects of assimilation. However, the nativity differences send a clear signal that protective factors are weakening in both sexes.
Our findings are consistent with other cross cultural studies that show that despite wide variation in base rates of dual diagnoses, patterns of dual diagnoses reported in this study are fundamentally similar across cultures and ethnic groups (Swendsen et al., 1998
; Swendsen & Merikangas, 2000
; Smith, Stinson, Dawson, Goldstein et al, 2006
). Women had lower substance disorder rates than men, however women were more likely to report a dual diagnoses conditional on having a substance disorder. Men reported lower non-substance disorder prevalence than women yet had higher rates of substance disorders conditional on having a non-substance disorder. Among men the most prevalent form of dual diagnoses involves alcohol disorders, which has important behavioral consequences for the Latino population in terms of increasing arrest and incarceration rates (Vega, 2001
In order to establish a more comprehensive understanding about dual diagnoses among Latinos, information is needed about lifetime patterns of recurrence and severity of disorders, the relative independence of comorbid non–substance disorders as contrasted with substance-induced
non-substance disorders, and the role of sub-syndromal disorders (e.g. depression or anxiety) as these affect the course of personal functioning, social role impairments and recovery (Nunes & Rounsaville, 2006
). There are also cross-cultural issues concerning measurement of DSM criteria, and these issues are inherent in the formatting and presumed conceptual universality and semantic equivalence of case-finding research instruments, including wording and sentence construction used in questions to elicit symptom endorsements (Room, 2006
It is rare for immigrant women with a lifetime mood or anxiety disorders to report a co-occurring drug disorder, occurring in only 1.69% of cases. However, immigrant women reporting a dual diagnosis had a very early onset of non-substance disorders, at a median age of only 11. While dual diagnoses are unusual in immigrant women, they are markers for exceptionally high risk. Elsewhere it was reported that immigrant women, who had entered the U.S. as children, had markedly lower exposure to major and traumatic events and this lowered their risk of drug disorders in their lifetimes (Lloyd & Taylor, 2006
; Turner et al., 2006
). The small proportion of immigrant women who met criteria for substance use disorders were presumably characterized by greater severity than reported by males with similar disorders (Booth et al., 2004
; Swift et al., 2000
; Warner et al., 2004
). In our study we found only one exceptionally high rate of dual diagnoses that occurred in Cuban women, an unexpected finding which may have resulted from random subsample atypicality.
The findings regarding progression sequences between substance and non-substance disorders confirm the report of Merikangas and others that non-substance disorders usually occur before onset of substance disorders (Compton et al., 2000
; De Graaf et al., 1993
; Merikangas et al., 1998
). In this study about 70% of dual diagnoses cases had (temporally) primary onsets of either (or both) a mood or anxiety disorder(s). Notably, the few foreign born women who had a dual diagnoses were distinctive in reporting greater likelihood of substance disorder onset before non-substance disorders.
Contemporary biobehavioral models explain the emergence of dual diagnoses as a product of shared genetic antecedents interacting with environmental factors that result in phenotypes of addictive and non-addictive disorders (Tsuang et al., 2001
). However, there are many unanswered questions about the phenomenology of dual diagnoses and its potential variability as a phenotype among ethnic groups or across societies. At this point we have no biomarkers for either substance or non-substance disorders for objective case identification and we rely on research interview information to identify cases. These methods are adequate for moving ahead with the search for integrated explanations of subgroup characteristics and nativity differences in dual diagnoses based on life course and intergenerational patterns of selection, family aggregation, social adaptation and assimilation, differential exposure to traumatic and persistent life strains, and variations in availability of coping resources (Turner & Lloyd, 2003
). The WHO World Mental Health Consortium (2004)
surveys reported odds ratios (and confidence intervals) for past 12- month drug disorders of 3.8 (C.I. = 3.2–4.5) in the U.S. and 2.5 (C.I. = 1.8–3.3) in Mexico – a nation that contributes the majority of Latino immigrants to the U.S. The comparative odds ratio for mood disorders in the U.S. was 9.6 (C.I. = 8.8–10.4) as contrasted with 4.8 (C.I. = 4.0–5.6) in Mexico. Therefore, most U.S. Latino immigrants are coming from societies with lower substance and non-substance disorder rates and they subsequently resettle in a society with higher normative tolerance for substance use and greater risk for lifetime use. This transition is accompanied by variable exposure levels to the cumulative adversity of migration and resettlement.
Explanatory factors can be organized and sequenced using behavioral genetics frameworks that test family aggregation patterns as building blocks for the investigation of gene - environment interactions. At a preliminary stage this research could estimate the effects of “context dependence” represented by transnational immigration and resettlement (Cooper 2003
; Institute of Medicine, 2006
). This type of research can contribute to identifying trait-related genetic variants in the differentiated populations that comprise the U.S. Latino diaspora (Wang et al., 2008
The contribution of putative intermediary mechanisms for dual diagnoses, such as ADHD, risk taking and impulsivity, could also be tested (Kendler, Myers, & Prescott, 2007
). These intermediary mechanisms may be mediated or moderated by cultural norms (Cherpital & Tam, 2000
) or sex linked biology and social constructions of gender (Kreiger, 2002
). Gender roles and accepted behaviors are rapidly transforming as a consequence of culture change and social adaptation in the U.S., as indicated by higher proportionate increases in Latino women than in men for dual diagnoses.