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A Study of Interactions: Emerging Issues in the Science of Adolescence - Workshop Summary 2 A Portrait of Adolescence To open the discussion, Robert Blum took note of some unprecedented challenges facing young people at the start of the 21st century: they are the first generation to grow up in a world characterized by instantaneous global communication and the threats of both AIDS and the widespread use of terrorism as a political weapon. They will be the first generation to fully compete in a global economy and the first generation of whom the majority will spend at least part of childhood in a single-parent household. The professionals who work with young people in this fast-changing environment need a clear understanding of the processes of adolescence, yet models for understanding this phase of life are rapidly changing in ways that can significantly influence practice. Recognizing that significant changes are occurring in the social contexts in which adolescents live, workshop participants focused on selected areas in which social influences may interact with biological and behavioral processes that occur during the second decade of life. Thus, it was important that the workshop begin with an overview of critical processes that emerge during adolescence and explore current views of what is going on in the minds and bodies of young people. Presentations by Ron Dahl and Elizabeth Shirtcliff, organized around the theme of new insights on pubertal maturation and adolescence from a developmental framework, provided this grounding.
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A Study of Interactions: Emerging Issues in the Science of Adolescence - Workshop Summary DEVELOPMENTAL CHANGES AND BRAIN MATURATION An understanding of adolescence begins with recognition that different sets of changes occur along separate trajectories during the second decade of life—and that changes in each arena affect developments in others. It is also important to note the significant individual differences in the ways that children experience these changes. Some aspects of puberty, such as the onset of biological changes, begin at younger ages today than a century ago (at around age eight for girls and nine for boys): children grow in stature and begin to develop the physical characteristics of adults earlier; production of the hormones that control sexual development increases and leads to reproductive maturity at younger ages. In many traditional societies, the interval between attaining puberty and taking on adult roles (such as marriage and employment) was typically two to four years. More recently, this interval has stretched to an 8- to 15-year period, creating a prolonged period of dependency, and stretching out the acquisition of the skills and responsibilities of adulthood. Some of the workshop participants indicated that this lengthening of the transition period may be one of the most important sources of change in the adolescent period over the past 100 years. It has also stimulated the development of a new set of studies focused on the population of 18- to 25-year-olds, who are increasingly viewed as encountering a separate stage of development termed “emerging adulthood.” Changes in mood and emotions occur during adolescence as well—as parents frequently observe, teenagers may rather suddenly display such changes as new emotional intensity, increased interest in romance, increases in risk-taking, and changes in sleep patterns. These affective developments may also be linked to the endocrine system, although the mechanisms through which this takes place are less well understood. Cognitive maturation typically occurs less suddenly, Dahl noted, and is independent of sexual development. It correlates more with age and maturity, and new research has been emphasizing that fundamental changes in brain development occur much later than had been recognized—continuing long after puberty is over. Children’s capacities for logic, reasoning, and planning continue to grow throughout adolescence, as do their problem-solving skills and capacity to understand the long-term consequences of their behavior—these capacities are far from fully developed as puberty is reached. The slower pace and more diffuse nature of cognitive development—and the fact that it occurs independently of other developmental changes—
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A Study of Interactions: Emerging Issues in the Science of Adolescence - Workshop Summary are particularly important to the overall picture of adolescent behavior. As data from a number of countries have established, the adolescent period for young people in the developed world has lengthened dramatically over the past 100 years. While the onset of puberty has occurred at ever-younger ages, the time frame for cognitive development and the development of adult skills has remained unchanged. As a consequence, many young people today reach sexual maturity by the time they are 12 or 13, on average, yet cognitive maturity does not come until their early 20s. This increase from what used to be a 2- to 4-year interval to a period of 8 to 15 years has posed significant new challenges to adolescents and the adults and institutions with whom they interact. At the same time, changes in social norms and expectations as well as cultural developments—from music and clothing styles to technology—have dramatically affected the contexts in which young people in the developed world are growing up.1 The lengthening of adolescence interacts with the changing environment of adolescence to “turbocharge” the strong emotions and exacerbate the gap between some young people’s physical abilities and motivations and their ability to process information and regulate their behavior. Dahl referred to this situation as the “tinderbox in the teenage brain,” which can cause difficulties in the presence of certain stressors or the absence of key supports. INTERACTING INFLUENCES Social context and the independent trajectories of sexual, affective, and cognitive development are just some of the many other factors that influence outcomes for young people. Looking at any of them alone would yield an incomplete and potentially misleading picture of adolescence, but the interactions that affect adolescents are even more complex than this list suggests. Dahl emphasized the importance of studying adolescence within a developmental framework, that is, an approach in which the concerns of psychiatry, pediatrics, endocrinology, affective neuroscience, and other fields can be integrated in an understanding of other forces that influence stages of change and developmental outcomes. He focused his presentation 1 The workshop focused primarily on the adolescent experience in the United States. Growing Up Global is an in-depth study that examines the adolescent transitions in the developing world (National Research Council and Institute of Medicine, 2005).
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A Study of Interactions: Emerging Issues in the Science of Adolescence - Workshop Summary on neurobehavioral changes—reward seeking, sensory stimuli, and the development of emotion regulation—to highlight how interactions among different phenomena can amplify individual differences among young people and also to demonstrate the value of transdisciplinary research for benefiting both clinical work and social policy. Dahl described early adolescence as a period of brain development that creates unique vulnerabilities and opportunities, and one in which achieving a successful balance is challenging. During puberty, pubertal-related hormones directly influence physical drives (such as appetite and sleep), motivations, and emotions, whereas cognitive and regulatory controls over behavior are established in a more gradual and indirect manner. The increasing gap between these two processes creates a time of increased vulnerability and risk as well as opportunities to develop particular strengths and positive behaviors. Strategies that strengthen social support, or “scaffolding,” especially during vulnerable intervals, are thus critical means of supporting youth, particularly those who are growing up in high-risk environments. What is especially important during this time is enhancing the adolescent’s ability to control and regulate emotions in navigating unfamiliar social situations, a skill that is related to self-control. The lack of these skills is related to impulsivity, reckless behavior, and problems in resolving complex emotional situations. Recent research also suggests that puberty is a time of significant malleability in the neural systems that underpin behavior, emotions, and decision-making. The affective changes—ranging from increased sexual interest and emotional intensity to risk-taking and sensation seeking—that adults observe are the manifestations of this malleability. Emerging neuroscience studies on the brain structure, hormonal processes, and neural signals that influence behavior control, Dahl explained, offer important implications for understanding adolescent behavior. Complex pathways emerge within the adolescent brain for evaluating situations, reacting to them emotionally, and assessing possible reactions. The strength and speed of the neural connections that govern these functions are shaped by genetic traits, by experience, by social context, and by learned emotions. For adolescents, these pathways are developing. This biological process, combined with incomplete cognitive development and the challenges presented by the environment in which a child lives, make adolescents particularly vulnerable to emotional and behavioral difficulties (e.g., depression, social anxiety), regulation of appetite and reward motivation (e.g., sub-
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A Study of Interactions: Emerging Issues in the Science of Adolescence - Workshop Summary stance abuse, eating disorders), and impulsivity (e.g., antisocial behavior, excessive risk taking).2 Furthermore, these neurological developments take place in a context, and they are influenced not only by the social environments that surround young people but also by their own choices and preferences as well as the consequences of their decisions. Genetics dictates some aspects of temperament and may predispose individuals to physical and mental characteristics that affect their daily lives. Attitudes and actions are in turn shaped by these circumstances, which are then complicated by the developmental process of adolescence and by the social context. These dynamic models of person-environment interactions are gaining increasing attention, Dahl suggested, as researchers realize that adolescents become active agents in shaping their own social settings and experiences. They select certain types of settings and context as a means of regulating their own behavior, arousal, motivation, and emotions. At the same time, certain contexts (especially those that involve electronic media) deliberately recruit teens through the enhancement or manipulation of selected sensory and emotional triggers. Broader awareness of these triggers in the social environments of youth can help intensify protective factors, discourage vulnerabilities and influences that lead to negative trajectories, and enhance their potential for self-regulation. Thus, to look at a concrete example, a girl may put on weight as puberty begins. A genetically based vulnerability to depression, combined with the negative attitudes of a peer group that prizes thinness, may intensify her reaction to a small weight gain. Cognitive immaturity makes it difficult for her to put the situation in perspective. Mood swings (possibly hormone related) and social anxiety intensify her reactions, and she may develop an eating disorder. The presence of the eating disorder may affect both her health—even hormone levels—and her relationships with her parents and peers, which in turn affect her ability to handle further challenges, and so on. The issue of teenagers’ sleep needs, described in Box 2-1, provides another example of the influence of interactions among many factors, yet all too often little attention is paid to these underlying interactions in studies of the treatment and prevention of health disorders, such as obesity and many others in adolescent populations. 2 Some researchers dispute the view of adolescence as a time of impulsivity and invulnerability (see work by Millstein et al., 1999, and Millstein and Halpern-Felsher, 2002).
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A Study of Interactions: Emerging Issues in the Science of Adolescence - Workshop Summary Box 2-1 Teenagers and Sleep Parents often complain about teenagers who want to sleep until noon. Recent efforts to persuade school officials to adjust high school start times to accommodate teenagers’ sleep patterns attest to growing recognition that their circadian rhythms are different from those of adults and younger children. Two changes in sleep patterns have been specifically linked to puberty. First, because of rapid growth and development, teenagers need more sleep overall and show both daytime sleepiness and a need to catch up on sleep on weekends. At the same time, their circadian rhythm shifts slightly toward staying up later at night and sleeping later in the morning. Ron Dahl used the sleep issue in the workshop discussions to illustrate his broader point about interactions. Teenagers’ sleep needs have become a problem in part because stimulating activities—television, music, computer games, phone and email conversations with friends—are available to them in the late evening, which exacerbates what would otherwise be a mild tendency to be wakeful. The shortage of sleep that results affects adolescents’ functioning, sometimes in drastic ways. Significant impairment of cognitive function, emotions that lurch out of control—these effects of sleep deprivation can lead to significant stress on their own, which can in turn exacerbate problems with sleeping. As Dahl put it, “you can’t study sleep without going across disciplines.” Sleep deprivation can be a tipping point that pushes a struggling child over the edge into dysfunction, and it is influenced by sociocultural and social factors, parenting, and policy (school start times), as well as the neural, cognitive, and hormonal activity of adolescence. The interrelationships among the factors that influence this hypothetical girl’s development are complex, and they illustrate how easy it is for the balance to tip in the direction of dysfunction for a given child. Dahl emphasized, however, that in this dynamic person-environment interaction, the presence, support, and interventions of caring adults can make a major difference in the outcome for a child. While some have argued in the past that peer influence begins to supersede the influence of parents and other adults during adolescence (Harris, 1998), this is far from definitely proven. Parents may exert influence in different ways as their children age, and the effect is still profound.
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A Study of Interactions: Emerging Issues in the Science of Adolescence - Workshop Summary HORMONES—EVEN MORE COMPLICATED THAN YOU THOUGHT While many neuroscience studies focus on biological changes associated with brain development, others are reexamining assumptions about the hormones that are “raging” during adolescence. These newer studies offer another perspective on interactions among and nested relationships within neurobehavioral models and social context models that influence the affective developments of adolescence. Elizabeth Shirtcliff offered some thoughts about the neuroendocrine contributions to pubertal development and the current state of research in this area (Shirtcliff, 2005). Shirtcliff pointed out that hormones are important biological markers for endocrine mechanisms that influence normal developmental processes as well as regulatory disorders. Hormones identify areas of vulnerability or a biological predisposition that may be subject to change in certain settings or after certain interventions. She explained that hormones function differently in adolescents than in adults, noting that the links between hormone levels and behavior are not as direct as was once thought. Levels of many of the hormones that are thought to “rage” in adolescence are actually higher in adulthood than in adolescence. Moreover, hormones cycle rapidly, and their cycles rarely correspond directly to cyclic changes in mood or other behaviors. One important recent finding, Shirtcliff observed, is that certain hormones are very active early in a child’s life, even in utero and during the first two years of life. During early childhood a large inhibitory control, or brake, emerges in the endocrine system that is not lifted until the onset of puberty. This overarching hypothesis is known as the organizational activational hypothesis. The basic underlying idea is that the reawakening of certain hormonal impulses following a long period of dormancy can increase the potential for disequilibrium which in turn has large and long-term effects on behavior. This is because the cyclic hormonal systems and the feedback loops between the brain and other regions of the body are just getting established. Shirtcliff discussed three sub-hypotheses of the organizational activational hypothesis that each focus on different processes. Proponents of the adjustment model, for example, suggest that adolescents are more sensitive to very small hormonal fluctuations because their bodies are in the process of adjusting to the reactivation of a number of hormones. The same hormones may have very different effects in adults, perhaps in part because the shifts in level during adolescence are more abrupt and irregular.
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A Study of Interactions: Emerging Issues in the Science of Adolescence - Workshop Summary The biosocial model, by contrast, focuses on interactions between hormone levels and social context—and is supported by data showing that high-quality relationships with parents seem to protect teens from the potentially damaging effects of extra high or low levels of testosterone. In a third view, the mediation model, hormones play a secondary role in influencing behavior. Body changes for which hormones are responsible, such as the development of secondary sex characteristics, are actually the prime influences on behavior. Thus, for example, the body changes of puberty can occur rapidly or can make a child feel out of sync with his or her peers for a variety of reasons—and it may be these effects that influence body image, social relationships, mood, and other areas that fluctuate during these years. Shirtcliff highlighted interactions among biological and social factors that influence adolescent behavior. She noted that not only can individual hormone function predispose a child to a particular disorder, but also that evidence increasingly suggests that social context can affect the way hormonal effects are expressed. Certain interventions focused on settings and social processes, such as those that increase social support or decrease levels of stress in an individual’s environment, may actually affect hormone function or the expression of certain hormonal influences. For example, high levels of testosterone might contribute to leadership or social dominance in one context or to deviance and risk-taking behavior in another. The presence or absence of parental support or other caring adults may be an important contextual variable that can influence these types of outcomes through the regulation of impulsivity, self-control, and navigation of complex emotional signals. Shirtcliff emphasized that the brain serves as the hub of interactions among the endocrine system, the body’s neurocircuitry, social context, and behavior—and that findings from a variety of disciplines are necessary to understand the pathways and implications of these interactions. Some specific, intriguing questions about these interactions remain unanswered. Shirtcliff noted, for example, that the influence of the neuroendocrine system on parent-child conflict, mood swings, drug use, and other problems has not been well examined. She also pointed out that much existing research fails to take into account potential gender or ethnic differences, and that significant differences in terms of timing and many other factors may have important implications for understanding the way hormones influence adolescent behavior. In short, the interactions of neuroen-
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A Study of Interactions: Emerging Issues in the Science of Adolescence - Workshop Summary docrinology, biological processes, and social settings are arenas in which transdisciplinary research is clearly needed. CHANGING CONCEPTUAL MODELS Blum observed that the last major synthesis of research on adolescent health and development was prepared by the Office of Technology Assessment in 1991 (U.S. Congress, Office of Technology Assessment, 1991). Since that time, significant shifts in thinking about adolescence have occurred that can affect the expectations of parents and the other adults who work with teenagers. He noted, for example that as recently as 1990, gender-specific behaviors were largely attributed to social learning. Today, research advances have shown that the neuroendocrine system affects gender variations, and that these differences have significant effects on information processing, learning, and behavior. Blum also observed that researchers in 1990 believed that parental influences diminished as peer influences increased during adolescence. Today, there is agreement that parents remain as critical during adolescence as they were in childhood, even as peer influences increase. For example, such studies as the longitudinal Adolescent Health survey have demonstrated that the presence or absence of maternal support during early stages of adolescence can influence the timing of first sexual encounters as well as the number of partners for young girls (Centers for Disease Control and Prevention, 2003). Over the same time period, those who study adolescence have generally moved from a conceptualization of adolescence grounded in the stages of life described by 20th century scholars, such as Piaget and Erickson, to an ecological model in which contextual factors and social settings are viewed as major sources of influence on developmental processes in a young person’s life. As a result, increasing attention is focusing on the ways in which social and cultural factors in the environment of today’s youth exacerbate or soften sources of stress and disruption that influence biological, behavioral, and developmental processes. Another significant conceptual shift has been from a risk or deficit model—a focus on all that can go wrong with teenagers—to what is called a positive youth development model. Such a model—particularly relevant to the design of programs for young people—incorporates protective factors and emphasizes ways of tapping young people’s passionate enthusiasms, energy, and potential in positive ways (National Research Council and Institute of Medicine, 2002). While the positive youth development
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A Study of Interactions: Emerging Issues in the Science of Adolescence - Workshop Summary model, discussed in greater detail below, has had an important influence, many youth programs and policies remain focused on adolescence as a time of high risk. Several presenters offered perspectives on the most prevalent dysfunctional behaviors while also expressing frustration with the persistent compartmentalization of research communities, which inhibits their ability to address underlying processes that cut across many of these problem areas.
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