The proportion of variance explained by genetic variants on GWAS chips ranges from 4 to 13% . It is possible that a significant portion of the heritability can be explained by SNPs not tagged by GWAS chips, including rare variants . For instance, a recent study showed that rare variants explained 1-2% of phenotypic variance and 11-18% of total SNP heritability of substance use phenotypes . Nonetheless, rare variants are often not analyzed when calculating SNP heritability, which can lead to an underestimate of polygenic effects, as well as missing biologically relevant contributions for post-GWAS analyses . Equally important is the need to include other sources of -omics data when interpreting genetic findings, and the need to increase population diversity . Therefore, a multifaceted approach targeting both rare and common variation, including functional data, and assembling much larger datasets for meta-analyses in ethnically diverse populations, is critical for identifying the key genes and pathways important in AUD.Temperament refers to early emerging, “constitutionally based individual differences in reactivity and self-regulation” . Reactivity is conceptualized in terms of affective and motivational responses to stimuli, and captures, for example, the tendency for some children to feel threatened in response to novel stimuli and others to feel intrigued. Self-regulation refers to individual differences in the top-down control of reactive processes, grow trays and goal setting and goal striving behaviors; it reflects the fact that children differ in the ability to control their appetitive impulses, as illustrated in delay of gratification tasks .
One prominent model posits that childhood temperament can be partitioned into three broad dimensions: effortful control, negative affectivity, and surgency . Effortful control reflects an individual’s ability to control their attention and impulses. This domain is conceptually similar to the adult personality dimensions of disinhibition and conscientiousness . Negative affectivity captures an individual’s tendency to experience fear, anger, and other types of psychological distress. It is conceptually similar to the adult dimensions of negative emotionality and neuroticism . Last, surgency refers to an individual’s tendency to experience positive emotions and approach potential rewards. It is conceptually similar to the adult dimensions of positive emotionality , and extraversion . Traits related to effortful control, such as impulsivity, have the strongest and most robust connections with substance use . In contrast, results for negative affectivity are more equivocal. Some studies have found that negative affectivity predicts increased substance use , whereas other studies have not . There are even hints that negative affectivity can predict decreased substance use . Some of the inconsistencies might stem from the varying ways negative affectivity is conceptualized and measured . For instance, fear, anger, and hostility are all components of negative affectivity, but fear might protect against early substance use, whereas anger and hostility might increase risk . A related but somewhat more complex dispositional characteristic – aggressiveness – has also been linked to substance use . Aggressiveness can be thought of as an emergent behavioral tendency related to low levels of effortful control and high levels of surgency and negative affectivity . Although some have posited reciprocal relations between aggressiveness and substance use, White and colleagues found support for a unidirectional relationship whereby aggressiveness was related to subsequent substance use, but not vice versa.
Therefore, aggressiveness might be an especially important dispositional predictor of early substance use. One concern with the current literature on temperament and substance use is that many of the existing studies lack ethnic diversity. Stautz and Cooper noted that the majority of studies reviewed in their meta-analysis consisted of predominantly Caucasian samples. Although ethnicity moderated the relationship between impulsivity and substance use, the authors concluded that there was not enough ethnic variation to draw firm conclusions . Although Stautz and Cooper focused exclusively on alcohol use, their findings highlight the need to evaluate the relation between temperament and substance use in diverse populations. The current study helps address this gap by evaluating connections between temperament and substance use in a sample of Mexicanorigin adolescents. Substance use is a multiply determined outcome that is influenced by contextual, as well as dispositional, factors. A large literature suggests that family dynamics contribute to adolescent substance use, and that such processes may moderate the effects of dispositional variables . One family factor consistently related to substance use is parental monitoring , or, “parenting behaviors involving attention to and tracking of the child’s whereabouts, activities, and adaptations” . Monitoring is considered a protective factor against substance use, and studies confirm that increased parental monitoring predicts less use, even in high-risk and diverse samples. Despite the well-documented association between parental monitoring and adolescent substance use, the actual direction of the effect between these variables is controversial. Although it is typically assumed that parental monitoring reduces problem behaviors in adolescence, monitoring may also reflect the outcome of a reactive process whereby parents increase or decrease monitoring efforts in response to adolescent behaviors . Indeed, parents sometimes decrease their monitoring efforts when their adolescents engage in delinquency . Moreover, parental monitoring may serve a protective role only for youth who have dispositional tendencies toward substance use. That is, monitoring might decrease risk for youth who have temperamental traits associated with substance use , but be less relevant for adolescents who do not have such characteristics.
The current study will contribute to the existing literature by testing both additive and interactive effects of temperament and parental monitoring.Temperament—Adolescent temperament was assessed using the 64-item Early Adolescent Temperament Questionnaire – Revised . The EATQ-R scales assess three broad dimensions of temperament – effortful control, negative affectivity, and surgency . Effortful control was measured using 16 items that reflect activation control and inhibitory control . Negative affectivity was measured using 13 items pertaining to fear , and frustration . Surgency was measured using 6 items that assessed the amount of pleasure one derives from novel and “high intensity” experiences. The EATQ-R also contains scales assessing depressive mood and aggression. The depressive mood scale contains six items related to sadness and the loss of enjoyment in activities,drying marijuana and the aggression scale contains six items related to hostile actions and hostile reactivity. Temperament scores were obtained from both the adolescents , and their mothers . Ratings were made on a scale ranging from 1 “not at all true of you/your child” to 4 “very true of you/your child”. Sample items include, “It is easy for you/your child to really concentrate on homework problems”, “When you/ your child is angry, you/your child throw or break things”, and “You/your child feel shy with kids of the opposite sex”. Table 1 provides basic descriptive information for the EATQ-R scales, including alpha reliabilities and mother-child agreement correlations. All alphas were acceptable except for the surgency scale in the 5th grade; therefore, correlations based on this scale are likely to be attenuated by measurement error and should be interpreted with caution. Mother and adolescent temperament ratings were averaged together to form a composite score for each dimension. Although the mother-child agreement correlations were small to moderate , the same patterns of results emerged no matter whose ratings were used. Parental monitoring—Parental monitoring was measured using a 14-item scale adapted from Small and Kerns . This scale assesses the degree to which parents are aware of their youth’s behavior and various life circumstances using a response scale ranging from 1 “Almost never or never” to 4 “Almost always or always”. Adolescents completed the scale once in reference to their mother, and once in reference to their father. Sample items include, “Your Father/Mother knew how you spent your money”, “When you went out, your Mother/Father asked you where you were going”, and “Your Mother/Father knew what you were doing after school”.
Monitoring scores were computed by summing up responses to the individual items. Adolescent reported maternal and paternal monitoring were correlated , so scores were averaged to create one composite “Parental Monitoring” score. Mother and Father reported monitoring scores were kept separate. Substance use intentions: This 9-item scale, adapted from Gibbons et al. , assesses willingness to use particular substances, as well as plans to use those substances in the next year. Three items were dedicated to alcohol use, three to cigarette use, and three to “illegal drug” use. Participants responded on either a three or four point scale ranging from 1 “Do not plan to/Definitely will not/Not at all willing” to either 3 “Very willing”, or 4 “Do plan to/ Definitely will.” Sample items include, “How likely is it that you will drink alcohol in the next year”, and “Do you plan to smoke cigarettes in the next year?” Scores for this measure were computed by summing up the individual items. Substance use expectancies: This 18-item scale assesses positive expectations regarding the use of alcohol, cigarettes, and other drugs. The scale was developed by Rand Conger for use in the Family Transitions Project. Participants responded to a variety of “pro-drug” statements on a scale ranging from 1 “Strongly Disagree” to 5 “Strongly Agree”. Sample items include, “Drinking alcohol helps people relax”, and “Smoking marijuana makes life more exciting”. A total positive expectancies composite was created by aggregating across the items. Substance use: This 9-item scale, adapted from Elliott, Huizinga, and Ageton , measures lifetime use of a wide range of substances. Participants responded “yes” or “no” to questions such as, “Have you ever used or tried cigarettes?”, and “Have you ever used or tried beer – more than just a few sips?” “Yes” responses were coded as 1s, and “no” responses were coded as 0s. Responses across the scale were summed up to generate a total use variety score. Means, standard deviations, and reliability information are presented in Table 2 for parental monitoring, substance use intentions, substance use expectancies, and substance use. Prospective correlations are reported in Table 3. Aggression assessed in fifth grade was associated with future substance intentions and expectancies, as well as reports of actual use. Effortful Control was negatively correlated with future substance use variables, but the effect sizes were roughly half that of the correlations involving Aggression. Depressive mood was related to intentions and actual use, but not expectancies. Child reports of parental monitoring were related to substance use variables more consistently than parental reports. Overall, there were consistent prospective zero-order correlations supporting an association between certain individual differences and early substance use. Regression analyses were used to control for fifth grade levels of the respective substance use variables when predicting the ninth grade variables . As seen in Table 3, although controlling for the baseline substance use variables reduced effect size estimates, all relevant predictors remained statistically significant.1 We should note that endorsements of the substance use variables in fifth grade were quite low , and floor effects may have attenuated the predictive power of the fifth grade assessments. However, these distributions might simply reflect the reality of low substance use at relatively young ages . The prospective associations were supplemented with concurrent analyses using temperamental variables, parental monitoring variables, and substance use variables measured in ninth grade . The correlations tended to increase in magnitude, but the pattern was generally consistent with the prospective correlations. Aggressive temperament and child reports of monitoring were the strongest correlates of substance use intentions, expectancies, and actual use. Effortful Control was also consistently linked with these outcomes. We found support for the idea that certain temperamental traits are related to substance use, and some evidence that parental monitoring is associated with substance use. We also tested whether temperament interacted with parental monitoring to predict substance use variables. We focused on child reports of monitoring for these analyses because parental reports of monitoring were not generally associated with substance use outcomes .Prior to analysis, the three substance use variables were log transformed to address concerns about skewness . All predictors were grand mean centered, and interaction variables were computed as the product of the two centered variables. When the interaction term was significant in a regression model, a set of simple slopes analysis was performed for “high” and “low” levels of a given dimension of temperament. We first considered prospective relations, using temperament and monitoring assessed in 5th grade to predict substance use variables in 9th grade. Selected results are presented in Table 4.