Research Review: Siblings matter:A multi-level meta-analysis on the association between cannabis use among adolescent siblings

Background: Parents' and peers' cannabis use are well-documented predictors of youth cannabis use, however, relatively little is known about the influence of siblings' cannabis use. Hence, this meta-analysis investigated the association between sibling-youth cannabis use (disorder) and explored moderation by sibling type (monozygotic- vs. dizygotic- vs. non-twins), age, age spacing, birth order, gender, and gender constellations (same- vs. mix- gender pairs). When comparison data of parents' and peers' cannabis use (disorder) were also available in the included studies, separate meta-analyses on associations between parent-youth and peer-youth cannabis use (disorder) were additionally conducted. Methods: Studies were selected if they included 11- to 24-year-old participants, and investigated associations between cannabis use (disorder) among those youth and their siblings. These studies were retrieved via a search in seven databases (e.g., PsychINFO). A multi-level meta-analysis using a random effects model was performed on the studies, and heterogeneity analyses and moderator analyses were also conducted. PRISMA guidelines were followed. Results: We retrieved 20 studies (most of which originated from Western cultures) with 127 effect sizes for the main sibling-youth meta-analysis and found a large overall effect-size (r =.423), implying that youth had higher cannabis use rates when their sibling used cannabis, and this association was stronger for monozygotic twins and for same-gender sibling pairs. Finally, a medium effect size existed for the associations between parent-youth cannabis use (r =.300) and a large effect size for peer-youth cannabis use (r =.451). Conclusions: Youth are more likely to use cannabis when their siblings use cannabis. This sibling-youth cannabis use association existed for all sibling constellations, was larger than the association between parent-youth cannabis use, and was similar in magnitude compared to the association between peer-youth cannabis use—suggesting both genetic and environmental influences (e.g., social-learning) between siblings. Hence, it is important not to neglect sibling influences when treating youth cannabis use (disorder).</p

The co-development of friends’ delinquency with adolescents’ delinquency and short-term mindsets:The moderating role of co-offending

The companions in crime hypothesis suggests that co-offending moderates the link between peer delinquency and adolescent delinquency. However, this hypothesis has rarely been investigated longitudinally. Hence, this study investigated the co-development of friends’ delinquency and adolescents’ delinquency, as well as the co-development of friends’ delinquency and short-term mindsets (impulsivity and lack of school future orientation). Whether this co-development is stronger when adolescents engage in co-offending was also investigated. Three data waves with two year lags from an ethnically-diverse adolescent sample (at wave 1: N = 1365; 48.6% female; M(age) = 13.67; age range = 12.33–15.09 years) in Switzerland were used. The results from parallel process latent growth modeling showed that the co-development between friends’ delinquency and adolescents’ delinquency was stronger when adolescents engaged in co-offending. Thus co-offending likely provides direct access to a setting in which adolescents continue to model the delinquency they learned with their peers

The Puzzle of Adolescent Risk Taking : An Experimental-Longitudinal Investigation of Individual, Social and Cultural Influences

Adolescents are known as stereotypical risk-takers, as they engage in disproportionate levels of risk-taking (e.g., binge drinking and delinquency). However, meta-analytic findings based on experimental studies using behavioral risky decision-making tasks revealed that adolescents do not always engage in heightened risk-taking compared to children and adults. Namely, although adolescents took more risks than adults on such tasks, overall adolescents took equal levels of risks as children. Moreover, on tasks that provided the opportunity to avoid risk-taking, adolescents actually avoided taking risks more often than children. Finally, early adolescents engaged in more risk-taking than mid-late adolescents. Such results on age differences in risk-taking on experimental risk-taking tasks are meaningful for understanding real-world risk-taking, as adolescents’ performance on an often employed risk-taking task was shown to predict self-reported adolescent alcohol use, delinquency and risky traffic behavior. As for social predictors of adolescent risk-taking on such experimental risk-taking tasks, mere peer presence did not have a main effect on adolescent’s risk-taking on such tasks, however boys took more risks than girls in the presence of peers, while boys and girls took equal levels of risks when alone. Furthermore, in another experimental study, earlier maturing girls engaged in heightened risk-taking in the presence of peers to a greater extent than earlier maturing boys. Longitudinal results further revealed that friends’ and (older) siblings’ externalizing problems (delinquency and aggression), and mother-adolescent negative relationship quality are significant predictors of adolescent externalizing problems. Additionally, when considering adolescent phase and gender, for early adolescent girls, delinquent peer norms (and not delinquent peer pressure) predicted adolescent delinquency one year later. However, for early adolescent boys, delinquent peer pressure predicted adolescent delinquency one year later, but only when there were higher levels of mother-adolescent negative relationship quality. Moreover, mother-adolescent negative relationship quality also predicted middle-adolescent girls’ delinquency one year later. Although parents’ own externalizing problem behaviors did not longitudinally predict adolescent externalizing problems, experimental findings showed that mere mother and father presence decreased adolescent risk-taking on a risky decision-making task. Interestingly, mere sibling presence also decreased adolescent risk-taking. As for adolescent smoking, deviant peer pressure is also important for increases in smoking from ages 12 to 17, even when significant individual factors such as impulsivity are taken into account. Next, both cultural similarities and differences were demonstrated for links between adolescent risk factors and risk behaviors. For example, intention to use alcohol predicted alcohol use one year later for adolescents both in the Netherlands and on St. Maarten. Also, an interesting cross-national difference was found showing that whereas alcohol use predicted cannabis use one year later in adolescents on St. Maarten, the reverse was true for adolescents in the Netherlands. Finally, no ethnicity differences existed in the link between delinquency and depressive symptoms over three years, however, at two of the three waves, ethnic minority Dutch adolescents reported higher levels of depressive symptoms than ethnic majority Dutch adolescents, and a gender by adolescent phase moderation effect was present. Hence, a plethora of individual, social and cultural factors contribute to adolescent risk-taking

The Puzzle of Adolescent Risk Taking : An Experimental-Longitudinal Investigation of Individual, Social and Cultural Influences

Adolescents are known as stereotypical risk-takers, as they engage in disproportionate levels of risk-taking (e.g., binge drinking and delinquency). However, meta-analytic findings based on experimental studies using behavioral risky decision-making tasks revealed that adolescents do not always engage in heightened risk-taking compared to children and adults. Namely, although adolescents took more risks than adults on such tasks, overall adolescents took equal levels of risks as children. Moreover, on tasks that provided the opportunity to avoid risk-taking, adolescents actually avoided taking risks more often than children. Finally, early adolescents engaged in more risk-taking than mid-late adolescents. Such results on age differences in risk-taking on experimental risk-taking tasks are meaningful for understanding real-world risk-taking, as adolescents’ performance on an often employed risk-taking task was shown to predict self-reported adolescent alcohol use, delinquency and risky traffic behavior. As for social predictors of adolescent risk-taking on such experimental risk-taking tasks, mere peer presence did not have a main effect on adolescent’s risk-taking on such tasks, however boys took more risks than girls in the presence of peers, while boys and girls took equal levels of risks when alone. Furthermore, in another experimental study, earlier maturing girls engaged in heightened risk-taking in the presence of peers to a greater extent than earlier maturing boys. Longitudinal results further revealed that friends’ and (older) siblings’ externalizing problems (delinquency and aggression), and mother-adolescent negative relationship quality are significant predictors of adolescent externalizing problems. Additionally, when considering adolescent phase and gender, for early adolescent girls, delinquent peer norms (and not delinquent peer pressure) predicted adolescent delinquency one year later. However, for early adolescent boys, delinquent peer pressure predicted adolescent delinquency one year later, but only when there were higher levels of mother-adolescent negative relationship quality. Moreover, mother-adolescent negative relationship quality also predicted middle-adolescent girls’ delinquency one year later. Although parents’ own externalizing problem behaviors did not longitudinally predict adolescent externalizing problems, experimental findings showed that mere mother and father presence decreased adolescent risk-taking on a risky decision-making task. Interestingly, mere sibling presence also decreased adolescent risk-taking. As for adolescent smoking, deviant peer pressure is also important for increases in smoking from ages 12 to 17, even when significant individual factors such as impulsivity are taken into account. Next, both cultural similarities and differences were demonstrated for links between adolescent risk factors and risk behaviors. For example, intention to use alcohol predicted alcohol use one year later for adolescents both in the Netherlands and on St. Maarten. Also, an interesting cross-national difference was found showing that whereas alcohol use predicted cannabis use one year later in adolescents on St. Maarten, the reverse was true for adolescents in the Netherlands. Finally, no ethnicity differences existed in the link between delinquency and depressive symptoms over three years, however, at two of the three waves, ethnic minority Dutch adolescents reported higher levels of depressive symptoms than ethnic majority Dutch adolescents, and a gender by adolescent phase moderation effect was present. Hence, a plethora of individual, social and cultural factors contribute to adolescent risk-taking

Theoretical advances in research on the development of risk taking

The special series of articles on adolescent risk taking addresses the discrepancy between laboratory studies (see e.g., the meta-analysis by Defoe, Dubas, Figner, & van Aken, 2015) versus real-world data indicating a peak in risk behavior during adolescence. Such heightened adolescent risk-taking is a topic of strong current scientific interest and of paramount policy- and clinical- relevance. However, the commonly held notion that risk-taking is highest in adolescence (compared to other ages) is currently under scrutiny. Recent accumulating studies on adolescent risk-taking in controlled experimental settings show findings that challenge this conclusion. The Defoe et al.’s (2015) meta-analysis that summarized such studies concluded that adolescents indeed take more risks than adults on experimental risky decision-making tasks, especially when they receive immediate feedback on rewards and losses. However, children and adolescents take similar levels of risks—although adolescents actually engage in fewer risks than children when offered the opportunity to choose a sure option instead of a risky option. Thus, the following pertinent questions arise: compared to whom do adolescents take more risks? Why does this occur? And when is heightened adolescent risk taking more likely to occur? These questions call for a more comprehensive theory-driven approach to studying adolescent risk-taking. The current special issue aimed to respond to these questions. We invited eight researchers who had active programs dedicated to understanding adolescent risk taking to participate in this collection and were pleased that they took up this challenge. In addition, Defoe also contributed by expanding on a model that she and her colleagues only hinted at in the meta-analysis that inspired this issue