Reciprocal relations between internalizing symptoms and frequency of alcohol use: Findings from a longitudinal study of Mexican-origin youth.

Adolescence is a dynamic stage of development during which individuals transition into more challenging academic contexts, navigate increasingly complex peer and romantic relationships, and take on adult responsibilities, all while experiencing significant neuro-hormonal changes associated with puberty. These changes put adolescents at risk for myriad emotional and behavioral problems, known to markedly escalate during adolescence. Underage alcohol use, in particular, is increasingly common during adolescence (Johnston et al., 2014a), and contributes to risky sexual behavior, delinquency, school drop-out, and substance use disorders (Brown et al., 2009; Newcomb & Bentler, 1988; Trim et al., 2007). Alcohol use is also highly comorbid with anxiety and depressive disorders (NIDA, 2010). Two theoretical models have been advanced to account for this comorbidity. The self-medication model posits that individuals with pre-existing internalizing symptoms use alcohol to cope with their emotional distress and soothe its physiological concomitants (Trim et al., 2007; Wolitzky-Taylor et al., 2012). Support for the prospective effect of internalizing symptoms on alcohol use has been mixed (Fergusson et al., 2009; Hallfors et al., 2005; Lansford et al., 2008; Maslowsky et al., 2014; Wolitzky-Taylor et al., 2012). The alcohol-induced disruption model posits that alcohol use leads to internalizing symptoms by: (a) impeding the development of effective coping and self-regulatory skills; (b) inducing neurotoxic effects that impair cognitive functioning, which creates school-related stress; and (c) alcohol use dysregulates reward mechanisms in the brain, causing adolescents to focus on acquiring alcohol rather than engaging in more adaptive activities that reduce risk for depression and anxiety (Brook et al., 2002; King et al., 2004; Trim et al., 2007). Few studies have tested these mediation pathways, and even the prospective effect of alcohol use on internalizing problems in adolescence is not well established, especially in non-clinical samples (Frojd et al., 2011; Mason et al., 2008). The present research examined cross-lagged relations between frequency of alcohol use and internalizing symptoms, using data from a longitudinal study of 674 Mexican-origin youth (50% female) assessed at ages 14 and 16. The study extends previous research in several ways. First, whereas most prior studies examined concurrent associations between alcohol use and internalizing symptoms, we used longitudinal data to examine reciprocal prospective relations and thus establish the temporal order of the effects. Second, our measure of internalizing problems assesses symptoms unique to anxiety and depression, as well as symptoms common to the disorders, allowing us to elucidate which specific aspects of anxiety and depression are more or less relevant to alcohol use. This is important because the effects of depression on alcohol use appear to be more robust than the effects of anxiety (Hallfors et al., 2005; Hussong & Chassin, 1994; Kaplow et al., 2010), but is difficult to draw conclusions from this literature because many measures of depression include some anxiety content and many measures of anxiety include some depressive content. Third, whereas many prior studies have used clinical samples, our community-based sample allows for more generalizable inferences about how alcohol use and anxiety/depression are associated during normative adolescent development. Finally, we focused on a specific ethnic minority group, Mexican-origin individuals, that remains understudied in the context of alcohol involvement and internalizing problems, despite their growing representation in the population (U.S. Census, 2014), their early onset of alcohol use (Johnston et al., 2014b), and their increased vulnerability to psychiatric and substance use disorders the longer they are exposed to American society (Vega et al., 1998; 2000). Although the developmental pathways characterizing Mexican-origin and European-origin youth sometimes differ, in the present context we expected to find the same pattern of results observed in prior research. This expectation is based on the fact that the mediating mechanisms posited by the self-medication and alcohol-induced disruption models reflect basic processes that are unlikely to be culture specific; youth from all ethnic groups are likely to derive some self-medicating benefit from alcohol use and, similarly, alcohol use is likely to lead to impaired self-regulatory skills, neurotoxic effects on brain development, and dysregulated reward processes. Thus, we predicted that alcohol use and internalizing symptoms would be reciprocally related over time, such that alcohol use at age 14 would contribute to subsequent increases in anxiety/depressive symptoms from age 14 to 16, and anxiety and depressive symptoms at age 14 would contribute to subsequent increases in alcohol use from age 14 to 16. Establishing the generalizability of these reciprocal associations to Mexican-origin youth has important implications. Theoretically, it would suggest that the developmental pathways linking these factors are not culture-specific but rather reflect more basic processes. Practically, it would suggest that intervention programs targeting these pathways (e.g., trying to reduce alcohol use by reducing internalizing problems or improving coping skills) are likely to be effective with Mexican-origin youth. In contrast, if our results differ from prior research, this would highlight the possibility of culture-specific developmental pathways, and suggest that factors unique to Mexican-origin youth exacerbate or diminish the link between internalizing symptoms and alcohol use. For example, the hypothesized pathways may be weaker for first-generation (vs. more acculturated) immigrants, given that first-generation youth are less likely to turn to substance use despite experiencing heightened levels of stress relative to latter generation youth (Garcia-Coll & Marks, 2011). To evaluate this possibility, we tested whether generational status moderates the association between internalizing symptoms and alcohol use. Finally, because the association between internalizing symptoms and alcohol use can be influenced by co-occurring externalizing symptoms (Colder et al., 2013), we also examined the effects of internalizing symptoms after controlling for a measure of externalizing problems.