A sample item includes “In the last 12 months, have you driven a snowmobile, motor boat, Sea-doo, or all-terrain vehicle within an hour of drinking 1 or more drinks of alcohol?” Responses to this item include “Did not drive a snowmobile, motor boat, Sea-doo, or ATV in the last 12 month; Yes; No.” Participants answered 131 questions from this measure approved by the University IRB prior to completing questions from the DUSI-R. Items from the DUSI-R asked participants to indicate their frequency and behaviors, as well as their peer’s behaviors, pertaining to substance use. Sample items include “In the past year, did you drink large quantities of alcohol when you went to parties?”; “In the past year, did any of your friends regularly use alcohol or drugs?” Participants responded by indicating “yes” or “no” to all items. Participants responded to 142 IRB approved items from the questionnaire.These questions were interspersed with the OSDUHS and DUSI-R .Data were analyzed using SPSS 23.0. Adolescents reported their lifetime, past year, and regular usage of tobacco, alcohol, cannabis, pain killers , spice, heroin, Attention-Deficit/Hyperactivity Disorder medication , cocaine, methamphetamine , psilocybin, methylenedioxy-methamphetamine , and Lysergic acid diethylamide . Due to potential individual variation within our sample size, we grouped drugs into categories based on reported usage and perceived consequences among this age group as follows: Group I ; Group II ; Group III ; Group IV . We also categorized time points of usage by lifetime use, use in the past 12 months, and using frequently, as listed in the OSDUHS questionnaire . Using “frequently” was measured as 11-15 times a day for tobacco, 2-3 times a month for alcohol,vertical farming equipment and 6-9 times a year for all other substances. Endorsement of use was weighted based on the Group, whereby Group I drugs were assigned a weight of 1, Group II, a weight of 2, etc.
Each endorsement of a drug in the group was multiplied by the weight and added to the totals of the other Groups to create a Drug Use composite score. Additionally, we created composite scores based on time points by adding the scores generated from the grouped drugs across each respective time point. The goal of this study was to determine whether adolescent neural responses to social violations of expectations were associated with substance use behaviors. Our results indicate that adolescents who demonstrated increased ventral striatal response when expectations were violated used more Group I substances compared to adolescents who demonstrated a decreased VS response when expectations were violated. Older adolescents used more illicit substances, and used substances more frequently than younger adolescents. Most adolescents endorsed using Group I substances compared to other substances. Adolescents who had greater Rejection Sensitivity Questionnaire scores used substances with greater consequences. Ventral striatal activation to violations was greatest in adolescents who endorsed using the most Group I substances compared to adolescents who endorsed using the fewest Group I substances. Researchers have proposed that individuals who use substances may require greater prediction errors to elicit the level of reward exhibited in individuals who use fewer substances by comparison . Additionally, previous research has supported this difference, whereby adolescents who demonstrate a greater ventral striatal response to non-social violations of expectations were more likely to engage in risky behaviors . Perhaps, then, it is unsurprising that adolescents who demonstrate increased ventral striatum response when social expectations were met reported engagement in fewer risky activities by comparison—as these adolescents may require a diminished PE to elicit a dopaminergic or rewarding response. Self-reported happiness to violations of expectations from Study 1 mirrored the aforementioned neural responses; such that participants who reported using a minimum amount of Group I substances were less happy upon experiencing a violation of expectations compared to when expectations were met.
While this effect is not statistically significant, it does suggest that the ventral striatum activation from Study 1 is reflective of a reward prediction error, as adolescents’ self-reported responses were in accordance with their ventral striatum response to violations. Separating the data in this way allowed us to account for individual variation that may have otherwise been lost in analyses, and elucidates important differences in ventral striatal activation with respect to reported substance use. The current study’s novel contribution to the literature is in showing that ventral striatum activation to social feedback is associated with real-world behaviors. We hypothesized that adolescents who demonstrated increased ventral striatal recruitment to positive social violations of expectations would use more types of substances more frequently than adolescents who demonstrated decreased recruitment by comparison. We did not find this association to be significant in our analyses. Instead, we found that for socialtrials, adolescents who recruited the ventral striatum used Group I substances more frequently, and adolescents who recruited the VS when their social expectations were met used fewer Group I substances in the past 12 months and in their lifetime. While we expected an association between ventral striatal response to positive social violations of expectations to predict behavior, as previously mentioned in Chapter 2, it’s likely adolescents were happier/more rewarded when their social expectations were met. Thus, it is unsurprising that a neural region implicated in reward demonstrates greatest response to reinforcing social feedback, which in turn is most associated with real-world social behaviors in adolescents. We suggest that in line with the results on self-reported happiness, adolescents who recruit the ventral striatum when their social expectations are met would be more inclined to act in a way that supports meeting their peers’ expectations—such as avoiding engaging in risky substance use behaviors. Because many adolescents nationwide and in our sample endorse using Group I substances , it is then likely that adolescents who recruited the ventral striatum for social trials were attuned to social norms, and were more likely to engage in social behaviors that were greatly endorsed by their peers.
Consistent with national and regional reports on adolescent drug use ,4×4 grow tray we found that older adolescents in our sample used more substances more frequently than younger adolescents. Research has indicated that older adolescents have greater access to more substances than younger adolescents and are eager to model their older peers’ behavior . We also found that adolescents who reported feeling more sensitive to rejection used more Group IV substances . This is in accordance with literature suggesting adolescents who are more sensitive to rejection take more dangerous risks—including using dangerous substances and engaging in health-compromising activities with their peers . We propose these teenagers engage in such activities because they are concerned about being rejected by their peers if they choose not to. It is likely that factors that contribute to rejection sensitivity may be better predictors of this type of substance use. We suggest adolescents who are not sensitive to rejection do not feel the same pressure to make such risky decisions with such serious consequences—and for them, the potential consequences outweigh the potential rewards of engaging in those behaviors. While our study has notable strengths, we acknowledge its weaknesses—namely, our sample size. Admittedly, our sample is not large enough to generalize to a greater population of adolescents to suggest novel information about adolescent substance use. Instead, we relied upon existing published reports, and found substance use endorsement within our sample was relatively comparable to the national population. We found age was associated with self-reported substance use, and suggest it may function as a moderator between ventral striatal activation and self-reported substance use, as older adolescents have greater access to substances and likely have older friends who use substances . Additionally, we note that it would have been beneficial to collect substance use information at the first time point when they received a scan to 1) draw a more direct correlation to task behavior; and 2) determine how substance use behavior changes over the course of two years in adolescence. Future studies should consider data collection in this way to increase internal validity and shed light on differences in adolescent behavior over time. Our study makes a novel contribution to the prediction error literature in that it differentiates adolescent ventral striatum response to social expectations with their real-world behaviors. These differences suggest future research should consider whether neural responses to social violations of expectations could be predictive of behaviors in adolescence. We propose that adolescents who use socially acceptable substances recruit the ventral striatum and are happier in response to experiencing a violation of expectations, as they require a large violation of their expectation to achieve a rewarding sensation and are attuned to and prefer to learn new social information. We conclude that adolescents who feel rewarded when they receive new social information about their friendship are socially more likely to act in ways to reinforce a rewarding sensation when they are with their friends, including engaging in socially acceptable substance use.Adolescents are often faced with complex social decisions. Deciding how to behave in “the heat of the moment” can be challenging for an adolescent—in part because cognitively, they are capable of making an informed and rational decision, but also their decisions tend to be emotional in nature, which can override rational thought . This is supported by neurobiological research on adolescents, which suggests the limbic system is more responsive during adolescence, while the prefrontal cortex is less so by comparison .
Additionally, researchers have considered adolescence as a sensitive period for socioemotional development , where compared to other age groups , and other people teenagers are more attuned to peer feedback. Considering the developmental changes evinced in neurobiological processes, psychological processes, and social salience during adolescence, it is no wonder making well-informed decisions in an emotional context can be particularly challenging. Behavioral research has indicated that compared to other age groups and compared to when they are alone, adolescents make riskier decisions when they are in the presence of their peers . They also report being more susceptible to peer influence compared to other age groups . A neurobiological study assessing peer influence found that not only do adolescents take more risks compared to young adults or adults, they also recruit regions implicated in reward—including the ventral striatum more than young adults or adults . While these studies and others have assessed adolescent response to peer influence in a laboratory setting , very few have manipulated peer influence to assess real-world behaviors. In their study, Allen and colleagues presented adolescents with a hypothetical scenario and asked them to decide on their own whom to save from a planet before meeting with others to decide collectively. They found that after meeting with other peers, adolescents changed their original choices to be more aligned with the group’s decision. While some adolescents make decisions reflective of a hyperactive reward system coupled with a diminished cognitive control system , most adolescents report engaging in moderate amounts of risky behaviors , suggesting that adolescents are capable of making safer, albeit risky decisions in emotional contexts. However, individual differences may lead adolescents to partake in some risky behaviors but not others , and some peers may be more influential than others . Notably, not all forms of peer influence are implicit or subtle—some are more explicit and are typically considered “peer pressure” . Adolescents reporting on their own susceptibility to peer influence indicate that they are not often coerced, but instead go along with their peers in an effort to be accepted or more liked by them . Additionally, these adolescents are also more likely to partake in risky social activities when a best friend or a higher status/more popular peer is partaking . Taken together, it is likely that adolescents recognize the risk in using substances, but find the risk is outweighed by the reward of peer acceptance.To our knowledge, studies on peer influence in adolescents have primarily focused on the effect of the presence of a same-sex peer, though notably, adolescents are eager to impress members of the opposite sex . Because adolescence marks a time of sexual maturation and increased desire to find a romantic other , we were interested in understanding whether an opposite-sex peer would influence adolescent self-report. The first goal of this study was to attempt to experimentally manipulate peer influence in an adolescent sample to determine whether adolescent self-reported susceptibility to peer influence was associated with experimentally manipulated peer influence.