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Introduction 

Introduction

Author(s):

Dwight L. Evans

and Martin E.P. Seligman

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date: 26 June 2017

At least one in five youth suffers from a current developmental, emotional, or behavioral problem (Burns et al., 1995; Institute of Medicine, 1989; Irwin, Burg, & Cart, 2002; U.S. Department of Health and Human Services, 1999; Zill & Schoenborn, 1990). The prevention and treatment of such difficulties in adolescence is one of the major public health problems facing the United States. To help adolescents achieve their full potential both as youths and as adults, it is important that we focus resources on this issue now. Helping adolescents reach their potential involves the identification, treatment, and prevention of mental disorders that interfere with the adolescent's development into a successful adult. However, getting rid of the disorder is not enough. We need also to instill positive values and behaviors that enable formerly troubled young people to flourish, contribute to society, and be happy and healthy.

Our goal with this book is to provide a comprehensive evaluation of what we know, and what we don't know, about adolescent mental health to create a road map for further scientific study and point the way toward needed changes in social policy. Our hope is that the current volume can advance the field through a state-of-the-art summary of empirical research on adolescent mental health, positive youth development, and the treatment and prevention of mental disorders in this age group.

In this introductory chapter, we set the context for our evaluation of adolescent mental health. We first address the question, “why focus on adolescence?” Following this, we provide an introduction to the specific mental disorders that are the main focus of this book and define some of the terms used throughout the book. We next give an overview of some of these special characteristics of the adolescent period so as to give the reader an understanding of the importance of this period of life to mental health. This includes a brief introduction to brain development during adolescence and an overview of genetic and environmental processes that are important at this stage of life. We then orient the reader to the history and structure of this volume and provide the rationale for the set of concluding chapters.

WHY FOCUS ON ADOLESCENCE?

Adolescence, which we define here broadly as ages 10 to 22, is a unique and distinct period in the development of human beings. The unique aspects of this developmental period have enormous implications not only for mental health and disorder among young people but for adults as well. Adolescence is a critical period of development characterized by significant changes in brain development, endocrinology, emotions, cognition, behavior, and interpersonal relationships. This period of life is a transitional period of development that is foundational but also noticeably malleable and plastic from a neurobiological, behavioral, and psychosocial perspective.

From a mental health perspective, adolescence is important because most of the major mental disorders begin not in childhood but during adolescence. After onset in adolescence, many chronic mental disorders carry over into adulthood, leading to ongoing significant mental health impairment during the adult years. This later influence of adolescence applies to not only the major mental disorders but also a range of health habits that influence adult behavior and may influence medical diseases in adulthood. Specifically, adolescent development and behaviors set the stage for adult behavior in terms of use of substances (both legal and illegal) and dietary habits and can have an impact on the development and outcome of medical illnesses, such as cardiovascular disease, diabetes, obesity, osteoporosis, and HIV/AIDS.

The past two decades of research have revealed that many mental disorders are relatively common in adolescence. Details of epidemiological studies of mental disorders in adolescents are presented in each of the disorder-focused chapters in this volume. Some of the more striking examples are the following:

  • The lifetime prevalence rate of major depressive disorder in adolescence is estimated to be about 15%, but 20% to 30% of adolescents report clinically significant levels of depressive symptoms (Chapter 1).

  • Over half of young people have used an illicit drug by the time they graduate from high school (Chapter 17).

  • The 12-month prevalence estimates for anxiety disorders in adolescents range from 9% to 21% (Chapter 9).

  • Suicide is the third leading cause of death among youth (Chapter 21).

What is especially alarming is that the prevalence of some of these disorders has been on the rise over each successive generation. Certain changes over time in the nature of adolescence, and the environments that adolescents find themselves in, may be responsible for these observed increases in the prevalence of psychopathology in adolescence. A major factor is that adolescence itself is now more extended. Puberty has been occurring progressively earlier, particularly in developed countries such as the United States (Parent et al., 2003). At the other end, full-time work and marriage now occur later in life. Thus, if adolescence is defined in terms of the onset of puberty, the total time spent in adolescence is now longer than in the past, and if its upper end is defined as the end of formal schooling, the total time is now much longer. Access to and availability of potentially harmful environments and substances have increased. For example, many types of abusable drugs can now be ordered through the mail via the Internet (For man, 2003; National Drug Intelligence Center, 2002). Compounding the potentially negative consequences of harmful environments is the increasing behavioral independence of adolescents in association with less parental or even adult influence.

There are many unanswered questions about the ways in which the interplay between biology and environment lead to the alarming numbers of adolescents we now see afflicted with mental illness and why this seems to have worsened in recent years. However, what is clear is the need to make adolescent mental health a major public health priority. A decade ago, early childhood moved into the spotlight and became a major health priority, but from the point of view of mental health, adolescence may be the more critical transitional period given its neurobiological and behavioral plasticity. It is, moreover, likely the optimal time for prevention and treatment of psychopathology, and for the promotion of mental health and positive emotional and behavioral functioning. By increasing our knowledge of the causes, treatment, and prevention of mental disorders that begin in adolescence, we will help reduce the suffering and impairments associated with these disorders and reduce overall health care utilization. Furthermore, progress in adolescent mental health could prevent mental disorders in adulthood that have onset in adolescence and modify the prevalence or course of medical illnesses in adulthood that are related in part to adolescent behaviors or mental disorders.

WHY THESE DISORDERS?

For the current volume, we have chosen to concentrate on mood disorders, anxiety disorders, eating disorders, suicide, substance use disorders, and schizophrenia. These disorders represent the major mental disorders or public health issues among adolescents, with the exception that conduct disorder and attention-deficit hyperactivity disorder, two important disorders of adolescence, are not represented in the current volume. This decision was made because these disorders have clearer roots in childhood and they were extensively covered in the parallel book, A Guide to Treatments That Work (Nathan & Gorman, 2002), which focused primarily on adults.

Mood Disorders

Although for many years depression was considered a problem that afflicted only adults, in the last 30 years there has been increasing recognition that this disorder can and does occur in children, particularly in adolescents. Fifty years ago, its mean age of onset was near 30, but now it is closer to 15. As mentioned previously and reviewed in the chapters on mood disorders, major depressive disorder is now seen as not uncommon in adolescents. When it occurs, it often has a severe impact on school performance and interpersonal relationships of afflicted youth. Since depression is a recurring disorder, its onset in puberty predicts an increase in the incidence of major depressive disorder. This constellation of facts about depression suggests that the adolescent years are key to understanding the etiology and course of depressive disorders.

Although bipolar disorder occurs at a markedly lower prevalence than that of major depressive disorder, it often has an onset during adolescence and can progress into an extremely disabling condition during adulthood. Moreover, bipolar disorder is associated with high rates of suicide in adolescence. Identification and treatment of major depression and bipolar disorder in adolescence may be the key to preventing the insidious progression of these illnesses and thereby reducing the burden of the illness on the individual and society.

Anxiety Disorders

Each of the specific anxiety disorders (generalized anxiety disorder; panic disorder; agoraphobia; obsessive-compulsive disorder; posttraumatic stress disorder; simple phobia; social anxiety disorder; separation anxiety disorder) seen in youth occurs with relatively low prevalence, but combined together these disorders are relatively common. As described in chapters on anxiety disorders, some disorders (separation anxiety and phobic disorders) are more common in early childhood and then become less common by adolescence, whereas other disorders (panic disorder and agoraphobia) show the opposite developmental profile, increasing in adolescence. These changes suggest that something especially relevant to the nature and course of anxiety disorders is happening during the adolescent years and may provide clues to the etiology and prevention of these disorders.

Eating Disorders

The two major eating disorders, anorexia nervosa and bulimia nervosa, typically have their onset around the beginning of puberty. Aspects of adolescence provide a fertile context for the development of eating disorders during these years. As discussed in the chapters on eating disorders, there is a marked increase in energy requirements required to support normal growth and development, with caloric requirements for girls increasing by almost 50% and for boys, by 80%. Moreover, dieting related to self-perceived weight status is now extremely common among adolescents, with two of every three female high school students trying actively to lose weight. Both of these eating disorders are of concern from a public health point of view. The mortality rate among individuals with anorexia nervosa is particularly a concern. For bulimia nervosa, only about half of those with the disorder can be expected to recover, with the rest displaying an ongoing significant impact on physical and psychosocial functioning.

Suicide

Suicide among young people has become an increasing concern over the past several decades. Although there has been a decrease in suicides among youth recently, the suicide rate among youth is now over double what it was 50 years ago. Possible reasons for this increase, as discussed in the chapters on youth suicide, include higher rates of depression and substance use, lower family cohesion, and higher availability of firearms (which are used in about 60% of suicides). It may also be that increased awareness of suicide and documentation of suicides has contributed to an increase in recorded suicides over time. Although actual suicides are rare—about 8 per 100,000 among 15-to 19-year-olds—an alarming number of adolescents attempt suicide. Among U.S. high school students, almost 9% will have attempted a suicide in the past year. Despite the widely acknowledged importance of increased attention to the problem of youth suicide, the scientific evaluation of suicide prevention programs and risk factors associated with suicide is in its infancy. This area remains a high priority for the health of our nation.

Substance Use Disorders

Substance use is a ubiquitous problem among adolescents. Heroin, marijuana, cocaine, ec-stasy, methamphetamine, inhalants, as well as new so-called club drugs such as gamma-hydroxybutyrate, flunitrazepam, and ketamine, are all used and abused by youths. As detailed in the chapters on substance use disorders, educational and preventive programs have had some success, with use of substances among adolescents decreasing slightly in recent years. Unfortunately, there is historical evidence to suggest that as soon as one birth cohort of adolescents shows reduced drug use after learning about the dangers and consequences of a particular drug through either education or personal experience, the next cohort of children enters adolescence without such knowledge and is prone to experience the dangers of a particular drug on their own. Moreover, new drugs continue to appear, such as the newer club drugs, for which there are few scientific studies of the short-or long-term effects and little accumulated street knowledge of the consequences of use. The advent of these new drugs further contributes to the ongoing high levels of substance use among adolescents.

The largest substance use problem among adolescents is not illicit drugs but alcohol. Surveys have documented that 0.4% to 9.6% of adolescents meet diagnostic criteria for alcohol abuse, and another 0.6% to 4.3% meet criteria for dependence (Chapter 17). The behavioral and psychosocial effects of alcohol and drug abuse and dependence are alarming, with school performance and social functioning deteriorating significantly. Addiction to illicit drugs such as heroin and cocaine can lead to a variety of illegal activities, including dealing, prostitution, and robbery as ways to pay for a drug habit. Excessive drinking among adolescents has been linked to high-risk sexual behaviors, date rape, assaults, homicides, and suicides.

Of equal or greater concern are the long-term effects of substance use on the developing brain of adolescents. While the general public largely still views addiction as a moral or character problem, the scientific community increasingly has moved toward a disease model of addiction, with particular focus on the brain. Evidence for genetic vulnerability to addiction and the neuronal basis for many of the clinical features of substance dependence, including craving, tolerance, and withdrawal, have raised questions about the lasting effects of chronic drug use. In addition, as reviewed in the next section in this chapter, the adolescent brain is developing. There is a key neural vulnerability during the adolescent period: although the brain's reward system is fully developed in adolescents, other areas of the brain involved in decision making and judgment are not yet fully developed (see Chapter 17). Thus, the adolescent brain is ripe for experiencing the rewarding effects of drugs but without the decision-making capacity and judgment that would allow weighing the consequences of drug use.

Schizophrenia

Finally, although schizophrenia is often viewed as an adult disorder, it was included in this volume because its onset is often in adolescence. The outcome of schizophrenia is often devastating, with long-term chronic impairment lasting from adolescence or early adulthood throughout life. Basic research with neuroimaging and other techniques have begun to map out the relationship between brain development and the occurrence of schizophrenia in both children and adolescents. Thus, a focus on schizophrenia in adolescence can provide hope for a better understanding of the disorder, and early interventions at this stage of life can potentially lessen, if not prevent, some of the devastating effects of the disorder as it continues into adulthood.

WHAT IS ADOLESCENCE?

Adolescence is a distinct developmental period characterized by significant changes in hormones, brain and physical development, emotions, cognition, behavior, and interpersonal relationships. It has been defined as beginning with the onset of sexual maturation (puberty) and ending with the achievement of adult roles and responsibilities (Dahl, 2004). As mentioned previously, in terms of chronological age, the range for adolescence is broadly inclusive, roughly 10 to 22 years of age. For a number of reasons, this range is only a guide. First, there are wide individual differences in development. The onset of puberty, along with its associated hormonal and physical changes, occurs significantly earlier for some youth than for others. A second reason is that different facets of adolescent development are on a different time course. While hormonal changes occur at the beginning of adolescence, certain executive functions of the brain are not completely developed until the early 20s. Moreover, different developmental trajectories have been found for different cognitive and emotional processes (Rosso, Young, Femia & Yurgelun-Todd, 2004). A third reason for the difficulty in specifying an exact age range is evidence showing that, particularly in developed countries such as the United States, the onset of puberty is at an earlier average age than seen previously (Parent et al., 2003). At the other end, cultural changes, such as expanding enroll-ment in postgraduate education, have kept young people from assuming adult roles until well into their late 20s. Thus the typical age range of adolescence has been redefined over time, and there are differences in age range between cultures and countries. Regardless of the specific age range of adolescence, the nature of changes in the adolescent brain over time are crucial for understanding why this period of development is particularly important for mental health.

The Developing Brain

The brain undergoes changes throughout life, with intervals of modest change punctuated by periods of more rapid transformation (Spear, 2000). Periods of more dramatic change include not only prenatal and early postnatal eras but also adolescence (Spear, 2000). There are a number of specific changes in the brain during the adolescent years. These include synaptic changes, myelination (extensive maturation of myelin), changes in the relative volume and level of activity in different brain regions, and hormonal interactions with brain structures. Technological advances, particularly the development of functional magnetic brain imaging techniques, have contributed substantially to the recent increase in knowledge about these brain changes.

The primary synaptic change seen during adolescence is, counterintuitively, a major reduction in the number of synapses. Rakic, Bourgeois, and Goldman-Rakic (1994) estimate that up to 30,000 cortical synapses are lost every second during portions of the pubertal period in nonhuman primates, resulting in a decline of nearly 50% in the average number of synaptic contacts per neuron, compared with the number prior to puberty. There is a similar loss of synapses in the human brain between 7 and 16 years of age (Huttenlocher, 1979), but the scarcity of human postmortem tissue makes it difficult to provide a more detailed description of this phenomenon. Although the implications of the massive pruning remain speculative, it is likely that it reflects active restructuring of connections and the sculpting of more mature patterns, with a corresponding pruning of connections with very little activity. And we know, for example, that some forms of mental retardation are associated with unusually high density of synapses (Goldman-Rakic, Isseroff, Schwartz, & Bugbee, 1983).

The elimination of large amounts of synapses, which are presumed to be excitatory, accompanied by a reduction in brain energy utilization, transforms the adolescent brain into one that is more efficient and less energy consuming (Chugani, 1996; Rakic et al., 1994). These changes may permit more selective reactions to stimuli that in younger children activate broader cortical regions (Casey, Giedd, & Thomas, 2000).

Myelination is another brain process that occurs during adolescence. The speed of neural transmission is greatly increased during myelination as a result of the glial cell membranes wrapping around axons. Although certain areas of the brain, such as the visual cortex, show maturation of myelin during childhood, myelination continues for the long-distance neural connections in the frontal, parietal, and temporal areas throughout adolescence (Luna & Sweeney, 2004). It is hypothesized that the myelination seen during adolescence further contributes to the development of executive functions of the brain, including faster information processing, by facilitating the integration of distributed brain areas and enhancing local connections (Luna & Sweeney, 2004).

Adolescence is also marked by changes in the relative volume and level of activity in different brain regions. For example, there is an increase in cortical white matter density (due to myelination) and a corresponding decrease in gray matter, especially in frontal and prefrontal regions (Giedd et al., 1999; Sowell et al., 1999a, 1999b). The overall result of these varied changes is a net decrease in volume of the prefrontal cortex (Sowell et al., 1999b; van Eden, Kros, & Uylings, 1990). In the hippocampus and the amygdala, however, gray-matter volumes continue to increase during late childhood and adolescence (Giedd, Castellanos, Rajapakse, Vaituzis, & Rapoport, 1997; Yurgelun-Todd, Killgore, & Cintron, 2003). While frontal white-matter volume peaks at about 11 years of age in girls and 12 years of age in boys, temporal gray matter volume peaks at about 16.7 years in girls and 16.2 years in boys (Giedd, 2004). In contrast, the dorsal lateral prefrontal cortex, which controls impulses, doesn't reach adult size until the early 20's (Giedd, 2004). Consistent with these changes in brain structure is the finding that by the end of adolescence there is improvement in prefrontal executive functions, including response inhibition and organizational and planning skills (Fuster, 1989).

There are also developmental shifts in patterns of innervation, including the circuits involved in the recognition and expression of fear, anxiety, and other emotions (Charney & Deutsch, 1996). The responsiveness of the cortical GABA–benzodiazepine receptor complex to challenge increases as animals approach puberty (Kellogg, 1998), and there are maturational changes in the hippocampus in humans and in animals (Benes, 1989; Wolfer & Lipp, 1995), especially increases in GABA transmission (Nurse & Lacaille, 1999). Further, pubescent animals show lower utilization rates of serotonin in the nucleus accumbens than do younger or older animals (Teicher & Andersen, 1999).

Developmental increases in amygdala–prefrontal cortex connectivity are seen during adolescence, in work conducted in laboratory animals (Cunningham, Bhattacharyya, & Benes, 2002). There are also alterations in amygdala activation (Terasawa & Timiras, 1968) and in the processing of emotional and stressful stimuli. Lesions of the amygdala have opposite effects on fearfulness to social stimuli according to whether those lesions are in infant or adult monkeys (Prather et al., 2001). Although levels of negative affect and anxiety have been correlated with amygdala activity in adults (Davidson, Abercrombie, Nitschke, & Putnam, 1999), recent studies using functional magnetic resonance imaging (fMRI) to examine amygdala activation in response to emotionally expressive faces in younger individuals have yielded a varying mosaic of evidence (Killgore, Oki, & Yurgelun-Todd, 2001; Pine et al., 2001).

Maturational changes in the cerebellum and in the circuitry connecting the cerebellum to the prefrontal cortex continue throughout adolescence. Lesions of the adult cerebellum disrupt the regulation of emotion and interfere with performance of tasks requiring executive functions (Schmahmann & Sherman, 1998), although this is less apparent in those younger than 16 years of age (Levisohn, Cronin-Golomb, & Schmahmann, 2000).

These brain changes related to the circuitry that involves emotions interact with hormonal changes during this period, leading to parallel emotional and behavioral changes during adolescence. Early adolescence is characterized by a lack of emotional regulation, but by the end of adolescence there is substantially greater emotional stability and control over behavior, particularly impulsive behavior.

There are several other changes in the human brain that, while not unique to adolescence, occur from birth through adulthood. One of these is postnatal neurogenesis (development of new neurons). This ongoing development of new neural cells is now known to occur in several brain areas, including the hippocampus, the olfactory bulb, the cingulate gyrus, and regions of the parietal cortex (Nelson, 2004). Neurotransmitter systems in the brain, which are key to current biological perspectives on many mental disorders, also do not reach full maturity until adulthood (White & Nelson, 2004).

Hormonal Changes in Adolescence

Puberty results from increased activation of the hypothalamic–pituitary–gonadal (HPG) axis, which in turn results in a rise in secretion of sex hormones (steroids) by the gonads in response to gonadotropin secretion from the anterior pituitary. Rising sex steroid concentrations are associated with other changes, including increased growth hormone secretion.

There is also more activity in the hypothalamic–pituitary–adrenal (HPA) axis during adolescence. This neural system governs the release of several hormones and is activated in response to stress. Cortisol is among the hormones secreted by the HPA axis, and researchers can measure it in body fluids to index the biological response to stress. Beginning around age 12, there is an age-related increase in baseline cortisol levels in normal children (Walker, Walder, & Reynolds, 2001).

The significance of postpubertal hormonal changes has been brought into clearer focus as researchers have elucidated the role of steroid hormones in neuronal activity and morphology (Dorn & Chrousos, 1997; Rupprecht & Holsboer, 1999). Neurons contain receptors for adrenal and gonadal hormones. When activated, these receptors modify cellular function and influence neurotransmitter function. Short-term effects of steroid hormones on cellular function are believed to be mediated by membrane receptors. Longer-term effects (genomic effects) can result from the activation of intraneuronal or nuclear receptors. These receptors can influence gene expression. Brain changes that occur during normal adolescence may be regulated by hormonal effects on the expression of genes that govern brain maturation.

Gonadal and adrenal hormone levels are linked with behavior in adolescents. In general, both elevated and very low levels are associated with greater adjustment problems. For example, higher levels of adrenal hormones (androstenedione) are associated with adjustment problems in both boys and girls (Nottelmann et al., 1987). Children with an earlier onset of puberty have significantly higher concentrations of adrenal androgens, estradiol, thyrotropin, and cortisol. They also manifest more psychological disorders (primarily anxiety disorders), self-reported depression, and parent-reported behavior problems (Dorn, Hitt, & Rotenstein, 1999). The more pronounced relationship between testosterone and aggressive behavior in adolescents who have more conflicts with their parents demonstrates the complex interactions between hormonal and environmental factors (Booth, Johnson, Granger, Crouter, & McHale, 2003).

It is conceivable that hormones partially exert their effects on behavior by triggering the expression of genes linked with vulnerability for behavioral disorders. Consistent with this assumption, the heritability estimates for antisocial behavior (Jacobson, Prescott, & Kendler, 2002) and depression (Silberg et al., 1999) increase during adolescence. Further, the relationship between cortisol and behavior may be more pronounced in youth with genetic vulnerabilities. For example, increased cortisol is more strongly associated with behavior problems in boys and girls with a mutation on the long arm of the X chromosome (fragile X syndrome) than in their unaffected siblings (Hessl et al., 2002).

Genetics

Genetics plays a significant role in our understanding of adolescent mental health. Historically, diathesis–stress models of mental illness suggested that a constitutional vulnerability interacting with environmental stress led to the development of mental disorders. Research in recent years, however, has shown that more complex models are needed to understand many disorders. Genes are turned on and turned off throughout one's lifetime, and multiple genes are likely involved in many mental disorders.

Many of the mental disorders prevalent in adolescents are the subject of promising, ongoing genetic research. Schizophrenia is one example. Several candidate genes have been identified that influence the development of the brain, including processes that have been linked to schizophrenia such as the excitability of glutamate neurons, hippocampal function, and regulation of dopamine neurons by the cortex. The authors of Chapter 5 on schizophrenia speculates that disruptions in these processes during adolescence may be particularly problematic because of the dramatic changes in cortical development that occur during this period.

Another example of the role of genetics is recent research on the relationship between a genetic variable, polymorphism of the serotonin transporter gene, and the development of depression after exposure to child abuse (Caspi et al., 2003). Individuals with a certain polymorphism of the serotonin transporter gene were found to be immune to the depressogenic affects of child abuse, whereas those with a different form of the polymorphism were highly likely to develop depression after child abuse (Caspi et al., 2003).

The Environmental Context of Adolescence

In the developing adolescent, the environmental context provides an influence that interacts (positively or negatively) with that child's biology to produce behavior. Families, schools, peers, youth sports and after-school activities, and community and religious organizations are the main social contexts in which adolescents spend time and model interactions with adults and peers, and these contexts provide the general framework for adolescents to develop their own outlook on life. As youth move from childhood to adolescence, there is an increase in time spent with peers and a corresponding decrease in time spent with their family. Typically, there is also a natural tendency for conflicts with authority figures, including parents, to increase. These conflicts allow adolescents to find their own path in life and to begin to acquire the skills needed to succeed as an independent adult. As mentioned previously, the successful acquisition and application of skills to live independently mark the definition of the transition from adolescence to adulthood. There are also cultural differences in the nature and timing of the acquisition of these adult living skills during adolescence. Thus, environmental and cultural factors are inherently interwoven into the fabric of adolescence.

Each of the major external environmental contexts to which adolescents are exposed can have positive or negative influences on their mental health. Parents, friends, coaches, and teachers provide social support to adolescents that can bolster them during difficult times and help them develop in positive ways by serving as role models. But if these people are abusive, rejecting, or overly controlling toward a youth who is emotionally attached to them, the youth can suffer detrimental effects. Abuse, which is all too often physical and/or sexual abuse from adults, and trauma are also clearly risk factors for the development of mental disorders, such as posttraumatic stress disorder and major depression. Unfortunately, trauma and abuse are not uncommon in some settings. For example, a study of African-American male youth living in low-income housing in Alabama found that over three-fourths of the youth had been victims of violence. An even larger proportion (87%) reported witnessing at least one violent act (Fitzpatrick, 1997). Finally, a measurable impact of parental mental health, particularly parental depression, on child and adolescent mental health is beginning to be uncovered (see Chapter 1).

Although parental behavior or mental health has an impact on that of the child or adolescent, a case can be made that, beyond the extreme situation of abuse or neglect, parents are not the major influence on adolescents; instead, socialization that occurs in peer groups outside the home may be the more potent influence. Harris (1995) describes a number of influential processes that occur in peer groups. Adolescents who are part of a peer group are subject to “in-group” favoritism and “out-group” hostility. Peer groups also elicit within-group jockeying for status. Moreover, peer groups encourage adolescents to form close dyadic relationships, including the development of love relationships. Disruptions in these processes are part of the emotional turmoil of adolescence.

Peer groups, along with the media, also expose adolescents to popular culture, which can impact adolescent beliefs, values, and sexual behavior. One important example of this is described in Chapter 17: particularly during the 1960s to 1980s, popular culture affected the degree and nature of adolescent substance abuse.

Within each of the parts on mental disorders in adolescents, the role of environmental contexts as contributing factors or triggers in the development of such disorders is discussed. The positive influence of such environmental contexts is highlighted in Chapter 26 on positive youth development. These environmental contexts are important to understand, not only because of their etiologic or protective factors in regard to mental health, but also because they are the settings and vehicles for interventions among youth, as we discuss below.

Intervention in Adolescence

With all of the changes occurring during adolescence and the associated neurobehavioral vulnerabilities and resiliences, it is clear that this phase of life is an ideal time to target with interventions aimed at improving young people's lives. This is true for both the treatment of adolescent disorders and the prevention of both adolescent-onset and adult-onset disorders.

For many mental disorders, it is increasingly clear that the earlier the intervention, the better. For example, disorders such as schizophrenia and bipolar disorder have a progressive course, with onset in adolescence or early adulthood, followed by the potential for further deterioration with the occurrence of each subsequent episode of illness. Therefore, rather than waiting for an individual to meet all diagnostic criteria from the Diagnostic and Statistical Manual for Mental Disorders (DSM) for a psychiatric disorder, it may be far better to identify and treat individuals who have risk factors or display some of the early signs of the illness. In the case of schizophrenia, such early-intervention programs have shown promise in reducing the annual incidence of first-episode psychosis (see Chapter 6; Falloon, Kydd, Coverdale & Laidlaw, 1996).

These early-intervention efforts and the targeting of high-risk and other nondisordered populations speak to the importance of interventions that have a preventive perspective. Although treatment of actual disorders in adolescence will remain an essential aspect of adolescent mental health research and practice, prevention may be the key to diminishing the burden of adolescent and adult disorders on society. Accordingly, the current volume has a major focus on prevention. There are many forms of prevention, therefore, a brief history of the concept and definitions of relevant terms are presented here.

Early Public Health Prevention Classification System

Different types of disease prevention efforts were first defined from a public health point of view in 1957 by the Commission on Chronic Illness (Commission on Chronic Illness, 1957). Three types of preventive interventions were identified: primary, secondary, and tertiary.

Primary prevention was defined as the reduction of the incidence of a disease or disorder through the prevention of the occurrence of new cases of a disease or disorder before they occur (Commission on Chronic Illness, 1957). This definition was expanded to include interventions designed to promote general optimum health by the specific protection of persons against disease agents or the establishment of barriers against agents in the environment (Leavell & Clark, 1965). Widespread vaccination is an example of primary prevention.

Secondary prevention was defined as the reduction in the prevalence in the general population of recurrences or exacerbations of a disease or disorder that already has been diagnosed (Commission on Chronic Illness, 1957). This includes early detection and intervention to reverse, halt, or at least retard the progress of a condition (Rieger, 1990). An example of secondary prevention is the use of antihypertensive medications among those with high blood pressure to reduce the risk of cardiovascular complications such as stroke.

In contrast to primary and secondary prevention, tertiary prevention efforts do not seek to reduce the prevalence of a disease or disorder. Tertiary prevention is only concerned with the reduction of the disability associated with an existing disease or disorder (Commission on Chronic Illness, 1957). For those with allergies, removal from exposure to the allergen would be a tertiary prevention approach.

Although these prevention terms were widely used in various public health domains, there are clear problems in attempting to apply this classification system for prevention efforts to the mental health field. The system requires an appreciation of the linkage between a disease or a disorder and the cause of that disorder at different stages of development (Haggerty & Mrazek, 1994). For example, the primary prevention of adolescent depression requires knowledge of the causal factors related to depression and their operational relationships. Secondary and tertiary prevention require a similar knowledge base. In practice, however, prevention interventions are often applied without this level of knowledge. As a practical matter, many preventive interventions have been based on indirect associations or statistical relationships with an outcome that is desirable to prevent. The strength or lack of strength of these associations has often diminished the effectiveness of these efforts. As more has been learned about etiology, it has become clear that physical and mental health events and outcomes cannot be explained by simple causal relationships. Rather, they are the result of the complex interplay of biological, social, environmental, and intrapersonal risk and protective factors. Thus, the original definitions of prevention break down when applied to adolescent mental health.

Gordon's Definitions of Prevention

An alternative to the Commission on Chronic Illness (1957) definitions of prevention was proposed by Robert Gordon. This new system was based on the “empirical relationships found in practically oriented disease prevention and health promotion programs” (Gordon, 1983). These included programs designed for universal, selective, and indicated prevention.

The definition of universal prevention included all interventions targeted to the general public or to an entire population group not selected on the basis of risk (Gordon, 1987). This would include interventions such as use of seat belts and immunization programs that are desirable for everyone in the eligible population. Selective prevention is defined by Gordon as interventions that target individuals, or a specific subgroup of the population, whose risk of developing a disorder is higher than average (Gordon, 1987). For example, condom use programs among sexually active adolescents is a selective prevention effort. Once an individual in a high-risk group exhibits the early signs or symptoms of a disorder, indicated prevention efforts would apply (Gordon, 1987).

Institute of Medicine Definitions

To reduce confusion emanating from the use of both the Commission on Chronic Illness (1957) and Gordon (1983) systems, and to suggest definitions more appropriate to the mental health field, the 1994 Institute of Medicine report, Reducing Risk for Mental Disorders: Frontiers for Prevention Intervention Research, offered new definitions. The term prevention was used in this report to refer only to interventions that occur before the initial onset of a disorder. Prevention included all three elements of Gordon's system. Efforts to identify cases and provide care for known disorders were called treatment, and efforts to provide rehabilitation and reduce relapse and reoccurrence of a disorder were called maintenance. Further distinctions were made within the prevention category using Gordon's (1983) terms. These are the definitions that we have used for the current volume. The specific distinctions within the prevention category are given below.

Universal mental health prevention interventions are defined as efforts that are beneficial to a whole population or group. They are targeted to the general public or a whole population group that has not been designated or identified as being at risk for the disorder being prevented. The goal at this level is the reduction of the occurrence of new cases of the disorder.

Selective mental health prevention interventions are defined as those efforts that target individuals or a subgroup of the population whose risk of developing the mental health disorder is significantly higher than average. The risk may be immediate or lifelong. Biological, psychological, or social risk factors associated with or related to the specific mental health disorder are used to identify the individual or group level risk.

Indicated prevention interventions are defined as those efforts that target high-risk individuals who are identified as having minimal but detectable signs or symptoms that predict the mental disorder or biological markers indicating predisposition to the disorder. For example, individuals who have some symptoms of major depressive disorder but do not yet meet criteria for the disorder would fall into this group. Although this definition includes early intervention, it excludes individuals whose signs and symptoms meet diagnostic criteria for the disorder. In the Institute of Medicine (1994) definitions, interventions with individuals who meet diagnostic criteria would be considered treatment.

Definition of Additional Prevention Terms

A further clarification of potentially confusing terms used within the prevention field was presented in the 1999 Surgeon General report on mental health (U.S. Department of Health and Human Services, 1999). In this report, first (initial) onset was defined as the initial point in time when an individual's mental health problems meet the full criteria for a diagnosis of a mental disorder. Risk factors were defined as those variables that, if present, make it more likely that a given individual, compared to someone selected at random from the general population, will develop a disorder. Although risk factors precede the first onset of a disorder, they may change in response to development or environmental stressors. Protective factors include factors that improve an individual's response to an environmental hazard and result in an adaptive outcome. These protective factors can be found within the individual or within the family or community. They do not necessarily lead to normal development in the absence of risk factors, but they may make an appreciable difference in the influence exerted by risk factors. We have adopted these clarifications offered in the Surgeon General's (1999) report here.

It is also important to distinguish between the risk of onset and the risk of relapse of a disorder. This is important because the risks for onset, or protection from onset, of a disorder are likely to be somewhat different from the risks involved in relapse, or protection from relapse, of a previously diagnosed condition. In this book, the prevention of relapse is included in chapters on treatment, whereas the prevention of onset of a disorder is discussed in chapters on prevention.

Pharmacological Intervention in Adolescence

Psychopharmacological interventions in children and adolescents are now common. In part because of the availability of selective serotonin reuptake inhibitors (SSRIs) as well as increased recognition of depression and treatment seeking, there has been a substantial increase in antidepressant prescriptions for children and adolescents (Ofson, Marcus, Weissman, & Jensen, 2002; Zito et al., 2003). The U.S. Food and Drug Administration (FDA) has now granted approval for the SSRIs fluvoxamine, sertraline, and fluoxetine for the treatment of obsessive-compulsive disorder in children and adolescents, and for fluoxetine for the treatment of major depressive disorder in patients 8 years of age or older. In 2002, approximately 10.8 million total prescriptions were dispensed for the newer antidepressants among those 17 years and younger (Holden, 2004). About half of children and adolescents treated for depression in the United States receive medication (Olfson et al., 2003). Similarly, stimulant prescriptions for attention-deficit hyperactive disorder have also been on the rise, with one study finding that 9.5% of children 6 to 14 years of age were receiv-ing such medication (Rushton & Whitmire, 2001).

The use of psychotropic medication in youth has recently come under scrutiny because of a possible link between use of antidepressants and increased suicidality. On the basis of an inspection of safety data, in late 2003 the U.K. drug regulatory agency recommended against the use of all SSRIs, except fluoxetine, in treating depression among youth under age 18 (Goode, 2003). After examining reports by pharmaceutical companies of their drug trials and listening to testimony at a public hearing on the issue, the FDA issued a public health advisory on antidepressants in March 2004 (FDA Public Health Advisory, 2004; Harris, 2004). In their statement, the FDA asked manufacturers of 10 specific SSRIs to place detailed information about the drugs' side effects prominently on their labels, and to specifically recommend close observation of adult and pediatric patients for the worsening of depression and the development and/or worsening of suicidality.

In September 2004, an FDA advisory committee met to further review the issue of suicide and SSRIs. The committee concluded that there was evidence for an increased risk of suicidality in pediatric patients, and that this risk applied to all drugs examined (Prozac, Zoloft, Remeron, Paxil, Effexor, Celexa, Wellbutrin, Luvox, and Serzone). On the basis of this risk, the advisory committee recommended that any warning related to an increased risk of suicidality in pediatric patients should be applied to all antidepressant drugs, including older antidepressants and medications that have not been tested in pediatric populations. However, the committee also recommended that these medications not be removed from the market in the United States because access to these therapies was important for those who could benefit from them. The FDA subsequently announced that it generally supported these recommendations and was working on new warning labels for all antidepressants. The chapters on mood disorders and suicide in this volume carefully consider the risks vs. benefits of antidepressant use in youth.

Positive Youth Development

In addition to our focus on the treatment and prevention of mental disorders in adolescence, this book adds another important perspective on adolescent mental health: positive youth development. Rather than focusing on symptomatology, disorders, or problems, positive youth development deals with each youth's unique talents, strengths, interests, and future potential.

There are two major reasons why positive youth development is an essential aspect of adolescent mental health and is therefore included prominently in this book. The first is our emphasis on prevention. Preventive programs that target nondisordered populations (e.g., universal mental health prevention) often are oriented toward building strengths, such as social competencies, rather than directly addressing negative behaviors, emotions, or symptoms. A full understanding of the range of positive virtues and strengths and their relation to competencies, well-being, and the development of disorders, problems, and symptoms is therefore necessary to successfully design preventive efforts and evaluate their effectiveness.

The second reason that positive youth development features prominently in this book is our view that adolescent mental health is much more than symptoms and disorders. As parents, teachers, and mental health professionals, our goals are to prepare young people for the demands of life. Having no symptoms or disorder is not likely to be sufficient to insure that adolescents thrive and form positive connections to the larger world as they transition into adulthood. Successful achievement of positive mental health, satisfaction with life, and adjustment to society may have more to do with certain positive characteristics such as curiosity, persistence, gratitude, hope, and humor than with the absence of symptoms. Indeed, research has shown that positive external (i.e., family support and adult mentors) and internal (commitment to learning, positive values, and sense of purpose) factors in youth are associated with academic success, the helping of others, leadership, and decreased problems (Benson, Leffert, Scales, & Blyth, 1998; Leffert et al., 1998; Scales, Benson, Leffert, & Blyth, 2000; see Chapter 26 for more details).

The emphasis on positive youth development is complementary to the treatment and prevention of disorders. Adolescents will obviously continue to experience problems and disorders that need attention and treatment. Disorders themselves may be preventable or reducible through development of strengths and virtues. But by also addressing positive values and strengths, in disordered and nondisordered youth, we believe we can maximize the chances that successful lives will ensue.

The Settings for Interventions in Adolescence

The Mental Health and Substance Abuse Treatment System

Each of the chapters on disorders in this book identifies treatments and prevention programs that have been found to work. What has become increasingly clear is that the development of such efficacious treatment is only a first step toward improving public health. It is also essential to take into account the settings in which the interventions occur. Currently in the United States, there are significant challenges to providing quality care for youth and their families within the mental health and substance abuse treatment systems that serve these populations. The severity of these challenges are highlighted in two chapters on service delivery systems for adolescents, one by Myers and McLellan regarding the substance abuse service delivery system in the United States, and one by Hoagwood on the mental health service delivery system. Both of these chapters document systemic barriers to implementing evidence-based treatments in our existing service delivery system. One of the primary barriers, reviewed in greater detail in Chapters 28 and 29, is service fragmentation—that is, the fact that treatment of children and adolescents is performed by at least six separate systems: specialty mental health, primary health care, child welfare, education, juvenile justice, and substance abuse. Other barriers include poor access and use of services among minorities, lack of sustained family involvement, and fiscal disincentives under managed care. Thus, a research agenda for the future would not be complete without an understanding of and improvement in the relevant service delivery systems.

School Settings

Schools have long been recognized as an important context for adolescent mental health development and service delivery. In fact, schools have been described as the de facto mental health service delivery system for children and adolescents, with between 70% and 80% of those that receive any form of mental health service obtaining such services from within the school setting (Burns et al., 1995). Higher prevalence rates of mental disorders and higher rates of comorbidity have been found among children and adolescents receiving services within the special education services of school than in specialty mental health clinics or in substance abuse clinics (Garland et al., 2001).

More than any other setting, schools provide access to adolescents for assessment and intervention. Student functioning, at least in terms of cognitive functioning needed for successful academic achievement, is tracked regularly, and behavior is assessed by multiple observers (teachers). At the first sign of problems, interventions could be initiated, rather than waiting until serious disorders develop and the adolescent is brought to a psychiatrist. Preventive interventions designed to target large populations of adolescents are particularly well suited for the school setting.

Unfortunately, as described in Chapter 31 on adolescent mental health and schools, the current state of mental health services in school is poor. There is wide variability across states and between urban and rural locations in the availability of mental health services in schools, with only about half of high schools having on-site mental health services (Brener, Martindale, & Weist, 2001; Slade, 2003). Increasing the availability and quality of school-based services for the assessment, treatment, and prevention of adolescent mental health problems is therefore a central component of any plan for improving the lives of adolescents.

Primary Care Settings

A particular component of the service delivery system, primary care medical practice, merits special attention in regard to adolescent mental health. In a typical year, over 70% of young people visit a primary care physician (Wells, Kataoka, & Asarnow, 2001). Primary care physicians typically serve as the gateway to obtaining specialist care, including mental health services. However, primary care physicians are typically poorly trained in psychiatry and psychology. Results of a national survey of primary care residency programs revealed that the average program devotes about 100 hours over the course of 3 years of residency to psychiatry training, with little or none of this specifically in child and adolescent psychiatry (Chin, Guillermo, Prakken, & Eisendrath, 2000). Compounding the problem is the fact that primary care physicians have enormous time constraints, especially since the advent of managed care and health maintenance organizations. These time constraints make it difficult for primary care physicians to adequately diagnose mental health problems. A recent study of over 20,000 youths visiting a primary care physician revealed that such physicians identified mood or anxiety syndromes at a rate substantially lower than that found in epidemiological studies (Wren, Scholle, Heo, & Comer, 2003). Inaccurate or missed diagnoses will lead to inadequate treatment.

Chapter 30 addresses in more detail the issues of identification and treatment of adolescent mental health problems in primary care settings. A unique aspect of this chapter is the presentation of a new study, commissioned by the Annenberg Adolescent Mental Health Initiative, which evaluates the practices of primary care physicians who treat large numbers of adolescents in the United States. This study found that physicians are concerned about the mental health of their adolescent patients and regard mental health as an important responsibility. In addition, the vast majority of primary care providers believe in the efficacy of treatment for mental disorders. However, primary care providers report low confidence in their ability to diagnose mental health problems, and only half employ any screening technique at all to detect mental health problems in their adolescent patients. These results suggest that enhancement of the recognition of mental disorders and referral practices in primary care represents a significant opportunity to increase appropriate treatment of adolescent mental health disorders.

THE PURPOSE AND STRUCTURE OF THIS BOOK

We have four main objectives with this book. The first is to review and summarize the adolescent literature for the six disorders and for positive youth development. To understand similarities and differences between adults and adolescents with these disorders, an additional objective is to review and briefly summarize the adult literature for the six disorders. On the basis of these literature reviews, each chapter provides recommendations for future research directions that we hope will serve as a template for guiding scientific developments in adolescent mental health. By fostering a specific scientific agenda, our larger objective is to help promote good mental health and positive youth development among adolescents.

This book was designed to be similar to a parallel volume addressing adult mental disorders (A Guide to Treatments That Work, Nathan & Gorman, 2002). Despite many similarities, unique aspects of adolescent mental health necessitated some differences from the Nathan and Gorman (2002) volume. The primary differences are the overriding focus on prevention and the theme of positive youth development. In addition, we have included several chapters that address the settings in which adolescent mental health and positive youth development efforts occur, and one discussing an important barrier (i.e., stigma) to enhancing adolescent mental health.

A substantial amount of effort went into the planning and creation of this book. The work began with the creation of seven commissions designed to discuss the issues and challenges in adolescent mental health regarding schizophrenia, anxiety disorders, mood disorders, eating disorders, substance abuse, suicide, and positive youth development. Researchers and clinicians from around the world with expertise in these areas were recruited for participation. Each commission initiated their work with a meeting during which initial ideas were presented and critiqued. Following this, initial drafts of chapters were prepared. A meeting of participants from all commissions, approaching 100 individuals, was then held in January 2004 to review and critique summaries of the literature and future recommendations. Final chapters were then prepared.

Throughout the preparation of the book, there was wide agreement among participants that the six disorders represented a somewhat artificial way to delineate the problems of adolescence. There was recognition that more work was needed on the current DSM system in regard to criteria for diagnosing adolescent disorders. More importantly, however, was the awareness, documented in a number of research studies, that comorbidity was extremely common among adolescent mental disorders, and therefore that the disorders as presently conceived may not “cut nature at the joints.” Furthermore, it may be that what is most relevant to treatment and especially prevention is not the DSM disorders themselves but common pathways to these disorders. However, the six disorders were judged the best way to start the process of understanding adolescent mental health because the empirical literature is oriented around these disorders. The concept of common pathways is addressed within the recommendations of individual chapters, and again in the summary chapter.

Each of the disorder-focused chapters follows a common structure. The chapters begin by defining the disorder, including discussion of differences between childhood, adolescent, and adult manifestations of the disorder. Next, a review of epidemiological studies is presented to convey the public health significance of these disorders. This is followed by a review of theory and empirical studies pertaining to etiology and risk factors for the disorder. A broad perspective on etiology and risk factors is taken, so that empirical literature on personality and temperament, cognitive vulnerability, stress, interpersonal relationships, biological factors, genetics, gender, and early life traumas is summarized for each disorder, if relevant. All chapters then discuss comorbidity.

After thorough presentation of scientific knowledge concerning the nature of the disorder, each part then addresses intervention. This begins with treatment. A brief review of psychosocial studies in adults, including acute treatment as well as relapse prevention studies, is first given, followed by a more extensive review of adolescent acute-phase and relapse prevention studies. Pharmacological treatment studies in adults and adolescents are then reviewed. The concluding chapter of each part presents the commission's recommendations based on their literature reviews. These recommendations are outlined in terms of a research agenda for the future, summarized in regard to three questions asked separately about the nature of the disorder, treatment of the disorder, and prevention of the disorder: (1) What do we know? (2) What do we not know? (3) What do we urgently need to know? Chapter 26 on positive youth development necessarily deviates from the above structure but retains several of the elements, including parallel recommendations.

As mentioned previously, to improve adolescent mental health, some additional issues beyond research on treatment, prevention, or fostering of positive youth development also need to be considered. Four chapters on service delivery systems (mental health, substance abuse, primary care, and schools) provide the larger context needed for understanding how to foster improvements in adolescent mental health and positive youth development.

Chapter 27 addresses another significant barrier to improved mental health care: stigma. Penn et al. point out that often adolescents hold stigmatizing attitudes about those with mental disorders. By conveying these attitudes, the likelihood is reduced that those with disorders will seek and continue treatment. This chapter identifies factors that elicit or reinforce stigmatizing attitudes in both adults and youth, including negative labels, lack of contact with those with disorders, and negative portrayals in the mass media. The reduction of stigma is another way to increase the likelihood that adolescents will engage in treatment and prevention programs.

The concluding chapter of the book summarizes what has been learned about adolescent disorders, their treatment and prevention, service delivery systems, and barriers to care. In this chapter, a review of the key recommendations made by the seven commissions culminates in a call to the nation to make a sustained effort to enhance adolescent mental health through science and policy changes.

Adolescent mental health in the United States is, simply put, much poorer than it ought to be. We hope this book provides the reader with a new and comprehensive focus on adolescent mental health and positive youth development. To the extent that we have achieved that aim, we believe the recommendations contained here, if acted on, have the potential to (1) promote improved adolescent mental health and related physical health; (2) prevent adolescent and adult mental illness and related physical illness; (3) promote positive youth development and help adolescents reach their potential; (4) advance the treatment and rehabilitation of mental illness and related physical illness; and (5) raise the level of adolescent mental health to a standard that this nation can look on with pride.