Browsing by Subject "Adolescence"

Adolescence is a key point in the life course, and friendships during this time are strong predictors of health and behavioral outcomes. This dissertation seeks to understand the causes and consequences of friendship stability, answering the question: Friendships during adolescence are important, but does it matter how long they last? Chapter Two introduces a new measure of friendship stability and tests possible pathways by which it affects extreme outcomes, threatening oneself or others. The findings indicate that some of these mechanisms partially explain this relationship, but low network instability remains strongly associated with the outcomes.Chapter Three examines the possible causes of friendship dissolution, as adolescents are more likely to dissolve the more unstable their networks. This chapter simultaneously tests individual, dyadic, and structural predictors of dissolution. The findings suggest that ego’s perception of intimacy, as well as the structural and dyadic features of the relationship, are the most prominent predictors of dissolution. Additionally, the results suggest differing relationships between several structural and dyadic features when considering whether friendship is reciprocated. Chapter four examines the relationship between racial peer mixing and mental health. I tested the effect of having cross-race ties on mental health, conditional on individuals being a racial minority in their school population. I also test whether two contextual factors of egos friendships, intimacy, and stability–mediate this relationship. I found that when adolescents are minorities in their schools, cross-race friendships somewhat protect them from emotional distress, and that this relationship is minimally mediated by friendship intimacy.

Adolescence is a critical period for drug addiction in humans. Most lifelong drug addiction is initiated during adolescence and the progression from initial drug use to the expression of addictive behaviors occurs more rapidly during adolescence than in adulthood. The purpose of this work was to examine if the adolescent brain uniquely responds to the addictive stimulant cocaine. This was accomplished by comparing the following measures in adolescent and adult male rats: locomotor responses to cocaine across a range of doses in two acute cocaine binge models, plasma cocaine and brain concentrations, locomotor responses to apomorphine, the relative magnitude of locomotor sensitization induced by a single high dose of cocaine (40 mg/kg), and cocaine-induced c-fos and zif268 expression. We determined that young adolescent (PN 28) rats had greater stereotypy responses to all doses of a repeated dose cocaine binge (15 mg/kg), the highest dose of an escalating dose binge (25 mg/kg), and low dose apomorphine. In addition to showing exaggerated acute locomotor responses to cocaine, young adolescents demonstrated a form of intrabinge sensitization that was absent in adults. Exaggerated adolescent locomotor responses could not be attributed to cocaine metabolism as we did not observe greater cocaine plasma or brain concentrations in adolescents compared to adults. A single high dose of cocaine (40 mg/kg) induced more ambulatory and stereotypy sensitization in young adolescents than adults. Further, the magnitude of the acute locomotor response to cocaine predicted the magnitude of locomotor sensitization in individual adolescents. We also showed that cocaine dose-dependently caused age-specific increases in the expression of the plasticity-associated immediate early genes c-fos and zif268: low dose (10 mg/kg) cocaine caused greater increases in striatal c-fos expression in adolescents whereas high dose (40 mg/kg) cocaine caused greater increases in striatal c-fos and zif268 expression in adults. Both doses of cocaine stimulated bigger increases in cortical zif268 expression in adults compared to adolescents. Finally, we demonstrated that the coordinated expression of striatal c-fos and zif268 develops during adolescence: there was no correlation between striatal c-fos and zif268 expression in individual adolescents but a strong correlation was seen in adults. The results of these experiments demonstrate that adolescents have unique molecular responses to acute cocaine and may help explain how adolescents show unique adaptive changes following continued cocaine use.

Rising demographic diversity and persistent social inequality are two defining features of youths’ social worlds, and schools and neighborhoods are key developmental contexts where this component of contemporary life plays out. This dissertation aimed to better understand the developmental implications of these twin phenomena, focusing specifically on adolescence, a critical period of development characterized by profound neurobiological and social cognitive changes. Across three studies, I asked, (1) how does exposure to different types of diversity and inequality in schools and neighborhoods relate to adolescent mental health and academic engagement? and (2) how do these relations differ across contexts and according to individual socioeconomic and racial-ethnic identity?The first chapter examined the relation between how schools say they value diversity and adolescent belonging, mental health, and academic engagement across racial groups. Results indicate that when schools’ mission statements conveyed explicit support for diversity (versus exhibiting color-evasive ideologies), racial disparities in mental health, educational aspirations, and reading achievement were smaller. However, when there was a mismatch between how schools said they value diversity and how such values were put into practice, schools’ proclaimed support for diversity was negatively associated with mental health, especially among White youth. The second chapter examined how exposure to rising inequality within neighborhoods—vis-à-vis gentrification—may impact educational outcomes. I found small positive associations between living in a gentrifying (versus chronically disinvested) neighborhood and 12th grade cumulative grade point average, intentions to pursue higher education, and one dimension of school quality: exposure to experienced teachers. However, these potential benefits of gentrification were concentrated among youth who were not economically disadvantaged and White youth. Further, for Black youth, the relation between gentrification and postsecondary plans varied according to the degree of racial turnover occurring in gentrifying neighborhoods—Black gentrification was positively associated with intentions to pursue college, but White gentrification was not. The third chapter examined two psychological mechanisms through which living in a gentrifying neighborhood may impact reading and math achievement: educational aspirations and psychological distress. Overall, there was a positive direct association between gentrification and achievement, and limited evidence of mediation. However, the pathways linking gentrification to educational aspirations, psychological distress, and achievement differed across socioeconomic and racial groups in nuanced ways that illuminate the potential costs and benefits of living in a changing neighborhood during adolescence. These three studies contribute to advancing the education, adolescent, and neighborhood literatures by examining understudied aspects of schools and neighborhoods. Findings suggest that the relation between context, identity, and development is more nuanced than is often assumed, with policy implications for how schools and neighborhoods can better address rising demographic diversity and persistent inequality.

Background: Nutrition plays an integral role in the development and growth for the adolescent populations. Nutrition education programs promotes healthy dietary behavior changes by increasing the nutritional knowledge of the adolescents as well as positively influencing the attitudes and food preferences. We aim to investigate the association between adolescents’ eating behaviors with their attitudes and food preferences. Methods: The Family Life, Activity, Sun, Health and Eating (FLASHE) dataset, consisting of a sample of 1657 adolescents 12-17 years old is a cross-sectional study assessing diet-related behaviors and factors correlated with those behaviors. We used the public dataset to investigate the association between food preferences and attitudes towards eating behaviors. Our statistical analysis approach consists of multiple correspondence analysis with our exposures (attitudes and food preferences) and separate ordinal logistic regression model. Results: [We found that five variables are positively associated with adolescents’ healthy eating behaviors, which are self-efficacy regarding eating fruits and vegetables on a daily basis (aOR=1.56, 95%CI=1.05-2.31), positive preferences towards water (aOR=2.45, 95%CI=1.60-3.73), fruit (aOR=2.01, 95%CI=1.18-3.40)and vegetables (2.63, 95%CI=1.82-3.79) as well as positive attitudes towards having a healthy diet (aOR=2.18, 95%CI=1.57-3.04). As for unhealthy eating behaviors, we found that positive preferences towards sugary sweetened beverages and soda have the highest estimate with increasing the consumption of unhealthy food products, with adjusted odds ratio of 2.52 (95%CI 1.79-3.55) and 1.93 (95%CI 1.36-2.73). Two other variables have the opposite effect, which are self-efficacy in limiting junk food consumption (aOR=0.71, 95%CI=0.49-1.00) and positive attitudes in having a healthy diet(aOR=0.67, 95%0.47-0.94). Conclusions: [We found that adolescents’ preferences are strong predictors for their eating behaviors. The attitudes and food preferences could influence their eating behaviors by increasing consumption of healthy food products and reducing the consumption of unhealthy food products. The results of our study is consistent with the Theory of Planned Behavior along with multiple research. Education and intervention programs should aim at empowering the young generation to foster positive attitudes and motivation to eat healthily.]

During adolescence, both boys and girls confront a period of heightened risk for dissatisfaction with weight and shape and engagement in unhealthy appearance-related behaviors. For many adolescents, this risk coincides with involvement in a range of romantic partnerships. Although a considerable body of empirical work has investigated same-gender peer influences on weight- and shape-related attitudes and behaviors, very little research has examined the role of romantic partners in this socialization process. Derived from social norms and social rewards theories of influence, this study examined several distinct modes through which romantic partners may influence changes in gender-specific behaviors and attitudes over a 6-month period. Participants included 214 (56% female) male and female adolescents ages 16-17 who reported having a romantic partner (of varying seriousness and relationship length) at Time 1. Results from multiple group (by gender) longitudinal path analyses revealed that both boys and girls experienced weight-related influence from a romantic partner. The seriousness and length of a romantic partner relationship moderated some, but not all, influence effects. Findings suggest that romantic relationships are important contexts for changes in adolescents' appearance-related health. Future research should examine romantic partners as contributors to both health-risk and health-promoting behaviors and attitudes.

This study examined changes in African American adolescents' racial identity content (e.g., connectedness, awareness of racism, and embedded achievement) and academic adjustment (e.g., Academic and disciplinary adjustment, perceptions of school and teachers, and relationship with school peers) between early and late adolescence. Data analyzed were from a subsample of youth (N = 514) who participated in the multi-site Fast Track Project designed to prevent problem behaviors (e.g., disruptive, aggressive, and antisocial behavior). Results from latent growth curve models suggest that connectedness and embedded achievement remain stable across adolescence. However, awareness of racism increases from early to late adolescence and this increase is linked to declining self reported relationships with school peers. These findings also indicate that the relationship between racial identity and academic adjustment is moderated by gender. For girls, awareness of racism predicted negative peer relationships in early adolescence, but not across the study years. For boys, increasing awareness of racism predicted declines in peer relationships across adolescence. The present findings contribute to the understanding of adolescent racial identity content change.

This dissertation investigates racial differences in individual stress processes and health as well as the ways social networks characteristics mediate these relationships. I explore (1) the stress trajectories of victims and non-victims from adolescence to adulthood across racial groups, (2) how particular network configurations determine the probability of adolescents experiencing victimization, and finally, (3) the ways racial homophily and social cohesion together, determine depressive symptoms. I conduct three studies all using relevant demographic, mental, and physical health data from the National Longitudinal Study of Adolescent to Adult Health. In my first study I find that black respondents have a unique relationship with the stress incurred from victimization, such that black victims and non-victims have virtually equal allostatic loads. In my second study I find that delinquency and integration shape the probability of victimization for adolescents, net of several common correlates of delinquency. Finally, results from my third chapter show that racial homophily mediates the well establish relationship between social cohesion and depression. These findings contribute to the sociology of race and ethnicity, network sociology, and to medical sociological inquires concerned with the vulnerable period of adolescence. Together, these three chapters show that race and networks govern opportunities that individuals have to form positive social relationships and the resulting health consequences of both successful and unsuccessful navigation of one’s social environment.

The current project is the first study to investigate the competence of academically gifted youth across multiple dimensions of the peer system. To date, there is no comprehensive examination of the social functioning of gifted youth, severely limiting what is known about the overall social world of gifted youth and the extent to which the subset of gifted youth with peer problems experience the same adjustment difficulties related to negative peer interactions. By examining how aspects of sociometric status, friendship and social network centrality relate to a myriad of outcome variables, the current study permits a comprehensive investigation of the risk profile associated with problematic peer relations among gifted youth within the adjustment domains (behavioral, academic and psychological functioning). Participants included 327 adolescents, 149 identified as gifted, who were initially assessed in the 7th grade and were then reassessed 2 years later.

Consistent with prior research, findings from the current student provided evidence that academic giftedness was generally associated with more positive peer relations as well as more positive functioning across behavioral, academic and adjustment domains when compared to non-gifted adolescents. However, findings from the current study did not find evidence suggesting that gifted youth experience significantly less peer problems than their non-gifted peers. As such, the current study substantiates predictions that there are indeed subgroups of gifted youth who experience peer problems and they were found to be similarly at risk as non-gifted adolescents with peer problems regarding negative behavioral, academic and psychological adjustment. However, the most alarming finding revealed that the negative effects of being rejected were more pronounced for gifted students, who were the most victimized students in the entire sample, even more than non-gifted peers who were rejected. Findings from the current study highlight the complexity of the social world of gifted adolescents and underscore the importance for future research to continue examining the social difficulties of gifted youth. Limitations and implications of these results are discussed.

Human social life requires navigating complex patterns of relationships that create underlying structures of social integration. In adolescence, teens manage close friendships while simultaneously evaluating their social position in broader peer groups and the larger school peer context. Social structures in each dimension of the peer network can relate to symptoms of mental distress, including depressive symptoms and self-harm, both critical health risks in this life course stage. Moreover, any association between network structure and mental health likely depends on contextual features that shape social relations and health, such as gender and friends’ mental health. In this dissertation, I examine distinct dimensions of social integration and contextual features of networks to clarify when social integration among peers relates to better and worse mental health for teens. Using survey data from PROSPER, I test the association of network position with depressive symptoms and self-harm by gender and friends’ mental distress.

In Chapter 2, I disentangle local and global social integration among peers by gender and friends’ depression to clarify how adolescent network integration relates to depressive symptoms. Analyses indicate global integration is protective for both boys and girls. Friends’ depression is largely irrelevant for boys. For girls with depressive friends, increased global integration predicts increased depressive symptoms, while greater local integration buffers associations between friends’ depression and girls’ own depressive symptoms. Results indicate the importance of considering distinct types of social integration by gender for depressive symptoms in adolescence.

Chapter 3 examines peer networks and self-harm, or intentional injury to one’s own body. I find that self-harm is largely unrelated to social position for boys, with only a small association between self-harm and being in the core of a peer group. For girls, however, greater integration among close friends and the overall peer network is associated with lower self-harm, unless friends are harming, then greater integration predicts higher self-harm. These results indicate that structures of cohesive close friendships and status among peers reduce self-harm risks for girls only in contexts where integration does not reinforce behaviors of harming peers.

Overall, this work demonstrates that distinct dimensions of social integration in peer social networks relate to depressive symptoms and self-harm in adolescence. However, these levels of structural integration should be considered in connection with features that shape the meaning of network structure. Further research is needed to define mechanisms linking integration to mental health, particularly self-harm, and to examine the consequences of this interplay between adolescent social integration and mental distress for health in subsequent life course stages.

Adolescence is the period of transition between childhood and adulthood, and is characterized across mammalian species by changes in behavior that include increases in risk taking, novelty/sensation seeking, and social behavior. Immaturity of the central serotonergic system during adolescence could contribute to risk taking behavior by resulting in lower avoidance of aversive stimuli in adolescents than adults. The purpose of this dissertation was to investigate whether immature serotonergic function could contribute to adolescent risk taking. We studied pre- and postsynaptic serotonergic function and circuit-level mechanisms relevant to risk taking behavior using behavioral and neurochemical approaches.

Serotonergic modulation of behavior was assessed in adult (67-74 day old) and adolescent (28-34 day old) male rats in the novelty induced hypophagia (NIH), elevated plus maze, (EPM), and light/dark (LD) tests for anxiety-like behavior. Serotonin depletion with the synthesis inhibitor p-chlorophenylalanine (PCPA) produced anxiolytic effects only in adult rats in the NIH test and in both age groups in the EPM. These data showed that some serotonin-mediated behavioral inhibition is present during adolescence. However, adolescent rats were less sensitive than adults to the anxiogenic effects of the serotonin releasing drugs fenfluramine and methylenedioxymethamphetamine (MDMA) and the serotonin uptake inhibitor fluoxetine in the LD test, suggesting that serotonin is not as effective at inhibiting behavior in adolescents as it is in adults.

Microdialysis conducted in medial prefrontal cortex (mPFC) showed that adolescent rats exhibited lower increases in extracellular serotonin after treatment with the releasing drug fenfluramine, but not the uptake inhibitor fluoxetine. Further investigation of presynaptic serotonin function in adults and adolescents revealed that adolescent rats have lower tissue serotonin content than adults in several forebrain regions, but similar rates of serotonin synthesis, density of serotonin transporter (SERT)-immunoreactive innervation, and SERT radioligand binding. These data suggest that adolescents may have a lower increase in extracellular serotonin than adults after a releasing drug, but not an uptake inhibitor, due to lower tissue serotonin stores. Lower serotonin stores may limit the ability of a releasing drug to increase extracellular serotonin, but are unlikely to affect response to an uptake inhibitor. These findings also indicate that extracellular serotonin does not completely account for lower serotonin-mediated behavioral inhibition in adolescents.

Since presynaptic serotonin function did not explain age differences in the anxiogenic effects of indirect serotonin agonists, we investigated postsynaptic serotonin signaling by testing the behavioral effects of serotonin receptor agonists in the LD test. Adolescent rats were less sensitive than adults to the anxiogenic effects of the 5-HT_1A agonist 8-hydroxy-2-(dipropylamino)tetralin (8-OH DPAT) in the LD test, but not to the 5-HT₂ agonist meta-chlorophenylpiperazine (mCPP). No age differences were observed in 3H-8-OH DPAT binding in prefrontal cortex, amygdala, or hippocampus between adolescents and adults, and infusion of 8-OH DPAT into mPFC (prelimbic cortex), ventral hippocampus, or basolateral amygdala was unable to replicate the systemic effects of 8-OH DPAT. These data suggest that lower adolescent sensitivity to the anxiogenic effects of 8-OH DPAT is not due to age differences in receptor expression, and show that 5-HT_1A stimulation in mPFC, ventral hippocampus, and basolateral amygdala alone is not sufficient to mimic the effects of systemic 8-OH DPAT.

We tested the circuit-level effects of fluoxetine and 8-OH DPAT, since stimulating 5-HT_1A receptors in single brain regions failed to reproduce age differences in systemic 8-OH DPAT administration. Both drugs activated regions of the amygdala more in adults than adolescents, and 8-OH DPAT also produced greater prefrontal cortical activation in adults. Fluoxetine produced greater expression of the immediate early gene c-Fos in regions of the extended amygdala in adult rats, and 8-OH DPAT produced greater activation of the lateral orbital cortex and central amygdala in adult rats. Lower activation of cortical and amygdala brain regions could underlie the lower behavioral effects of these drugs in adolescents, as these brain regions are important in mediating behavioral inhibition and anxiety-like behavior. These data are also consistent with human studies showing immature cortical and amygdala function during adolescence.

This dissertation shows that adolescents are less sensitive than adults to serotonin mediated behavioral inhibition, and that this may be due to immature activation of neural circuits modulated by the 5-HT_1A receptor between the prefrontal cortex and amygdala. This immature serotonin mediated behavioral inhibition could contribute to adolescent risk taking, drug abuse, and increased risk for suicidality during SSRI therapy for depression and mood disorders.