Adolescence—beginning with the onset of puberty and ending in the mid-20s—is a critical period of development during which key areas of the brain develop and mature. These changes in brain structure, function, and connectivity mark adolescence as a period of opportunity to discover new vistas, to form relationships with peers and adults, and to explore one’s developing identity. It is also a period of resilience that can ameliorate childhood setbacks and set the stage for a thriving trajectory over the life course.
Because adolescents comprise nearly one-fourth of the entire U.S. population, the nation needs policies and practices that will better leverage these developmental opportunities to harness the promise of adolescence—rather than focusing myopically on containing its risks. The National Academies of Sciences, Engineering, and Medicine were asked to convene a committee of experts to examine the neurobiological and socio-behavioral science of adolescent development and to outline how this knowledge can be applied, both to promote adolescent well-being, resilience, and development and to rectify structural barriers and inequalities in opportunity, enabling all adolescents to flourish. The challenge for a caring society is to take maximum advantage of the developmental opportunities afforded by adolescence to forge positive trajectories into adulthood for all adolescents.
Puberty occurs over an extended period of a young person’s life during which developmental changes result in the maturation of primary and
secondary sex characteristics and the acquisition of reproductive maturity. Pubertal development varies greatly from one individual to the next, and the age at which an adolescent matures depends on a combination of genetic and environmental influences, including early life experiences. Socially, pubertal maturation and its accompanying physical changes also affect how adolescents perceive themselves and how they are treated by others, and in this regard early pubertal timing has been shown to have challenging social consequences. Structural changes that disrupt the systemic factors that increase risk for early puberty (e.g., resource deprivation) as well as supportive relationships can mitigate the risks associated with early puberty and foster resilient outcomes.
Neurobiologically, throughout adolescence the connections within and between brain regions become stronger and more efficient, and unused connections are pruned away. Such developmental plasticity means adolescents’ brains are adaptive; they become more specialized in response to environmental demands. The timing and location of these dynamic changes are also important. The onset of puberty brings about changes in the limbic region of the brain, resulting in greater sensitivity to rewards, threats, novelty, and peers. In contrast, it takes longer for the cortical region, which is implicated in cognitive control and self-regulation, to develop.
Consequently, adolescent brains are not simply “advanced” child brains or “immature” adult brains, but have evolved to meet the needs of this stage of life. Indeed, the temporal discrepancy in the specialization of and connections between brain regions makes adolescence unique. The developmental changes heighten sensitivity to rewards, willingness to take risks, and the salience of social status, propensities that are necessary for exploring new environments and building nonfamilial relationships. Adolescents must explore and take risks to build the cognitive, social, and emotional skills necessary for productivity in adulthood.
The increased cognitive abilities gained throughout adolescence also provide the capacity for other aspects of psychosocial development, such as developing identity and capacity for self-direction. An adolescent’s identity is an emerging reflection of his or her values, beliefs, and aspirations, and it can be constructed and reconstructed over time and experience. Multiple factors, including family, culture, peers, and media, shape identity development, but young people are also active agents in the process. Ultimately, how adolescents’ multifaceted identities are manifested—neurobiologically, behaviorally, or otherwise—and what role identity plays in their overall well-being greatly depends on their experiences in particular social contexts.
Adolescence is also marked by a growing capacity for self-direction. Over the course of adolescence, youth gain the cognitive skills needed to reflect on complex questions about their role in the world. This enables them to question the legitimacy and fairness of everyday experiences and of
social institutions. Indeed, the social systems they must navigate—schools, employment, health care, justice—are complex, and navigating them often requires independent decision making. Such skills are important not only to support the transition to adulthood but also to make adolescence itself a period that fosters a propensity to contribute to others.
In summary, although adolescence is often thought of as a time of turmoil and risk for young people, it is more accurately viewed as a developmental period rich with opportunity for youth to learn and grow. Adolescence thus forms a critical bridge between childhood and adulthood and is a window of opportunity for positive, life-shaping development.
HOW ENVIRONMENT “GETS UNDER THE SKIN”: THE CONTINUOUS INTERPLAY BETWEEN BIOLOGY AND ENVIRONMENT
While the malleable brains of adolescents are adaptable to learning and innovation, they are also vulnerable to toxic exposures. The emerging science of epigenetics1 focuses our attention on the ongoing plasticity of the brain and the reciprocal influences of the brain, body, and environment. Contrary to the common understanding that the effects of heredity are immutable and direct, contemporary studies of gene-environment interaction and epigenetics show that the way heredity is expressed in behavior depends significantly on environmental influences. The epigenetic approach also embraces a “trajectory” model of the life course: the trajectory of an individual’s life may be changed, negatively or positively, at each life stage. Protective environmental factors support positive or flourishing trajectories, while adverse experiences may lead to at-risk or poor trajectories. The future condition of the brain and body will be affected by events that have changed the trajectory in the past, and interventions undertaken in the present have the potential to remediate past developmental challenges.
Adolescents’ heightened sensitivity and responsiveness to environmental influences also implies “resilience,” meaning adolescents have the opportunity to develop neurobiological adaptations and behaviors that leave them better equipped to handle adversities that emerge throughout the life course. Thus, investments in programs and interventions that capitalize on brain plasticity during adolescence can promote beneficial changes in developmental trajectories for youth who may have faced adverse experiences earlier in life or are facing them now and prevent future challenges and risks.
1 Epigenetics studies the seamless and ongoing interaction between genes and the environment, with particular interest in cataloging the numerous environmental mechanisms comprising the nongenetic influences of gene expression.
INEQUITY AND ADOLESCENCE
The promise of adolescence can be severely curtailed by economic, social, and structural disadvantage and, in all too many cases, by racism, bias, and discrimination. These potent societal determinants shape adolescents’ life-course trajectories in multiple ways, not only by reducing access to the opportunities, services, and supports enjoyed by more privileged youth but also by exposing less privileged youth to excess risks, stresses, and demands. These excess pressures “get under the skin” and adversely affect the brain and body during this critical developmental period.
Striking differences in opportunity are associated with striking differences in outcomes—in health, safety, well-being, and educational and occupational attainment—and in trajectories over the life course. Educational achievement, as measured by reading and math proficiency, high school graduation rates, and college completion, varies by race and ethnicity, socioeconomic status, and gender, with White and higher-income youth consistently experiencing better outcomes than other groups. Disparities also exist in the occurrence and impact of chronic health conditions (by socioeconomic status) and mortality (by race and ethnicity, socioeconomic status, and gender), due in part to exposure to violence. Moreover, there is consistent evidence that at all ages, LGBT youth are at higher risk of poor mental health and suicide than their heterosexual and cis-gender peers. Among adolescents, poor and Black youth are dramatically overrepresented in foster care. And in the juvenile justice system, Black youth are detained at a rate six times higher than White youth and three times higher than Latinx youth. (See Chapter 4.)
These disparities are often compounded for the youth experiencing them because they cut across the multiple systems with which they interact, and deficiencies in one area negatively affect outcomes in others. For example, poor health reduces educational attainment, while involvement in child protective services negatively affects juvenile justice outcomes. Together, these disparities grow as youth age and result in large disparities in their adult outcomes, such as poorer rates of employment and earnings, increased likelihood of criminal justice involvement, and poorer health and well-being.
However, disparities in adolescent outcomes are not immutable: they are responsive to changes in underlying conditions, and adolescents themselves show resilience and demonstrate strengths and assets that may be utilized to overcome inequities. Recent trends show that, in fact, adolescent well-being has improved over time, as illustrated by the steady decline in teen childbearing rates since 1990, which have been accompanied by significant declines in disparities by race and ethnicity.
Because a full understanding of the sources of these outcome disparities is necessary to formulate effective strategies for reducing them, we cat-
egorize the possible sources of these disparities as follows: (1) differences in family wealth and income, combined with living in neighborhoods segregated by income and race, (2) differences in institutional responses to adolescents by schools, the health system, the justice system, or the welfare system, and (3) prejudicial or discriminatory attitudes or behavior on the part of the adults or peers who interact with adolescents on a regular basis. Of course, other possible sources of outcome disparities exist, but here we point to some of the specific, quantifiable sources that have been captured empirically.
More than 9 million children and youth (ages 0 to 18) in the United States live in households with incomes below the poverty level, and rates of child poverty are highest for Black, Latinx, and American Indian and Alaska Native youth. For adolescents, growing up in poverty is associated with worse physical and mental health, as well as higher prevalence of risky behaviors and delinquency. The stagnation of wages for those in the bottom half of the income distribution over the past 50 years has reduced the resources available to lower-income families for investment in their children. Like income, wealth accumulation affects the resources families have available for investing in the next generation, especially for investments in higher education. Racial differences in wealth are three times greater than racial differences or gaps in income, with the average White household in 2010 having nearly six times the wealth of the average Black household (see Chapter 4).
In addition, because of the relatively high rates of residential segregation in the United States, adolescents from poor or minority families are much more likely than others to live in poor and segregated neighborhoods. Low-income neighborhoods, in turn, are more likely than other neighborhoods to be lacking in access to health care, youth-oriented organizations, and learning centers, and they are also more likely to be located near polluting factors, to have high levels of violence and low levels of safety, and to have low-quality housing. Moreover, poor families and minority families experience considerably more stress than others. As a result, not only are poor families less able to invest financially in their children, but also their nonfinancial investments, such as the amount and quality of their caregiving, are also affected by family disadvantage.
This disparity in family resources is often compounded by the institutions and systems with which youth interact. Segregation of schools by family income is the single most predictive factor of academic achievement gaps by race and income. The increasing income segregation of U.S. schools, compounded by rising income inequality, has most likely prevented society from achieving the full benefit of the significant, recent gains in financial parity across schools, suggesting that children from disadvantaged households likely need more resources (not equal resources) if society is to reduce
disparities in educational outcomes. School segregation is driven largely by neighborhood segregation and, as such, the policy or institutional response to the increasing segregation of U.S. schools largely lies in housing policy, but tightness in the housing market and housing discrimination reduce the likelihood that low-income families can move to low-poverty neighborhoods. Moreover, lack of health care access and low health care quality, as well as laws and policies that drive crossover from involvement with the child welfare system into involvement in the juvenile justice system, compound disadvantage and contribute to disparities in opportunity.
A third source of disparities in adolescent outcomes derives from the explicit and implicit (or unconscious) prejudice and bias that individuals hold against groups defined by race, ethnicity, gender, LGBTQ identity, ability status, and so on. The experience of being targeted by such bias can include both singular significant interactions as well as a series of less obvious but frequent events, referred to as micro-aggressions. At a time when adolescents are especially sensitive to the attitudes and behaviors of adult members of the community, evidence suggests that educators, health professionals, child welfare system actors, and justice system actors exhibit behaviors that lead to disparate treatment of youth by race, gender, LGBTQ identity, and ability status. When aggregated in an institutional context, these biases can result in disparate outcomes for the affected groups.
An effective strategy, or set of strategies, to reduce inequities needs to address the main sources of these disparities. The committee recognizes some promising policies and programs that attempt to tackle these disparities in opportunity, including (1) policies and programs to reduce disparities in income, wealth, and neighborhood resources, such as the Supplemental Nutrition Assistance Program and the Earned Income Tax Credit; (2) trauma-informed approaches preparing adults serving youth to address differential exposure to violence and trauma among youth; and (3) emerging tools, such as predictive analytics, to erase or counteract bias in decision making by system-level actors.
With any strategy, greater coordination is needed across the multiple systems responsible for adolescents: the school system, health care system, and juvenile justice and child protection systems. Parity in public system funding is a first step, but it will not be sufficient to significantly reduce disparities. To significantly reduce or eliminate disparities, disadvantaged youth will likely require disproportionate funding.
Although progress may not be immediate, there is substantial reason for optimism. Progress has already been made in reducing disparities in adolescent outcomes, especially in the areas of education, health, and teen pregnancy. With the notable exception of the juvenile justice system, the evidence suggests that as overall adolescent health and well-being improve, disparities fall. These trends underscore the hope that with additional effort
and a comprehensive approach, further reductions in outcome disparities among adolescents are indeed attainable.
USING DEVELOPMENTAL KNOWLEDGE TO ASSURE OPPORTUNITY FOR ALL YOUTH
The committee’s charge requested recommendations regarding ways by which youth-serving systems—education, health, child welfare, and justice—can apply accelerating knowledge about adolescent development (and particularly knowledge from the neurobiological and socio-behavioral sciences) to their own work. Of course, investing in youth also requires investing in the adult caregivers who support them, as supportive familial, caregiver, and adult relationships play a significant role in fostering positive outcomes for adolescents. Such investments need to be multilevel and multisectoral; interventions to change parenting behavior may be futile if the systems themselves are not attuned to the pressing economic needs of parents.
The following sections briefly identify the major domains of the committee’s recommendations for each of the four youth-serving systems designated in the committee’s charge: education, health, child welfare, and justice. Detailed recommendations for specific actors and actions can be found in Chapters 6 through 9.
Recommendations for the Education System
Our enriched understanding of adolescence, together with major changes in the labor market, require rethinking and modernizing a public school system that was largely designed for early 20th century life. As the economy has changed over the past several decades, the skills and dispositions required to succeed in the current and future job market are increasingly interpersonal and socio-emotional. Relatedly, today’s increasingly knowledge-based economy requires a mindset of learning, malleability, and expectation for growth and improvement.
When young people reach adolescence, they vary widely in their academic skills and needs and in their future career aspirations. The secondary school system of the future must meet teens “where they are” and offer differentiated and responsive academic opportunities, including individualized instruction, tutoring, tracking, and credentialing. Growing recognition of the importance of skills other than reading, writing, and arithmetic for both personal fulfillment and success in modern life requires schools to broaden their mission to incorporate the teaching of nonacademic skills such as decision making, practical knowledge, and adaptability. The growing diversity of U.S. adolescents also requires schools to better recognize
adolescents’ integrated needs, become more culturally sensitive, and become adept at assisting youth with issues related to identity and social competence. Moreover, recognizing the importance of caregivers in adolescents’ lives, the education system will need to provide additional supports for adolescents and their families to assist them in navigating an increasingly complex education sector.
In short, secondary schools should be modernized to reflect the preparation, knowledge, and skills that youth need for the 21st century and rectify longstanding and persistent disparities in resources across the demographic backgrounds of their students. This committee’s recommendations for transforming secondary education for the 21st century highlight six key areas to implement such change:
RECOMMENDATION 6-1: Rectify disparities in resources for least-advantaged schools and students.
RECOMMENDATION 6-2: Design purposeful but flexible pathways through education.
RECOMMENDATION 6-3: Teach practical knowledge and nonacademic skills, such as decision making, adaptability, and socioemotional competence.
RECOMMENDATION 6-4: Protect the overall health and well-being of each student.
RECOMMENDATION 6-5: Foster culturally sensitive learning environments.
RECOMMENDATION 6-6: Help adolescents and families navigate the education sector.
Recommendations for the Health System
Access to appropriate health care services is important to ensure adolescents’ well-being both today and for a lifetime. Access is particularly important while they are developing habits that will affect their long-term health, such as diet, exercise, and substance use. Yet adolescents face a variety of barriers to accessing health care, which contributes to longstanding disparities in their use of such care that are measurable by race and ethnicity, LGBTQ status, ability status, and socioeconomic status. While limited access to health care has been most frequently associated with financial barriers, adolescents face the additional challenge that they are
generally inexperienced in navigating the health care system independently, concerned that their health needs and services remain confidential, and more likely than adults to engage in risk-taking behaviors that could have both short- and long-term effects on their health.
Developmentally appropriate changes to provider practices and innovative care delivery systems can help adolescents become more engaged with their care and achieve better outcomes. To ensure the health and well-being of all adolescents, health systems should offer integrated, comprehensive health services that prepare youth for the distinct physical, cognitive, and social changes that take place during adolescence, prepare them to navigate the health system independently, and provide services that are culturally informed and attentive to the needs of all youth.
A systemic approach to prioritizing the health and well-being of adolescents is needed on a national level, including clear goals and priorities to help mobilize both the public and private sectors to improve adolescent health. The committee’s recommendations draw on neurobiological and socio-behavioral research to identify more effective health policy, programs, and practices with five key aims:
RECOMMENDATION 7-1: Strengthen the financing of health care services for adolescents, including insurance coverage for uninsured or under-insured populations.
RECOMMENDATION 7-2: Improve access to comprehensive, integrated, coordinated health services for adolescents.
RECOMMENDATION 7-3: Increase access to behavioral health care and treatment services.
RECOMMENDATION 7-4: Improve the training and distribution and increase the number of adolescent health care providers.
RECOMMENDATION 7-5: Improve federal and state data collection on adolescent health and well-being, and conduct adolescent-specific health services research and disseminate the findings.
Recommendations for the Child Welfare System
The purpose of the child welfare system is to protect children at risk of abuse or neglect by their parents or guardians (or whomever the state defines as a perpetrator). Historically and up to the present day, two defining aspects of the child welfare system have been its focus on young children and its attention to preventing serious physical abuse. These foci are
coupled with a funding scheme that prioritizes funding for out-of-home placement. As a result, the system is under-resourced in providing support services to prevent out-of-home placement and in providing support to families, particularly families with adolescents. This approach is ill-suited to helping adolescents in the child welfare system flourish, given their more advanced decision-making skills, their need for a balance of autonomy and healthy relationships, and their ability to use technology to seek solutions, relative to younger children. In addition, courts with jurisdiction over adolescents as a result of acting-out behaviors for status offenses have insufficient resources to address the underlying and presenting problems of these youth and their families.
Also of great concern are disparities within the child welfare system: poor children and children of color are disproportionately referred to the child welfare system. In general, both disproportionate need and differential treatment by community members and the child welfare system play important roles in explaining these disparities. Community reporters are more likely to report children of color to child welfare authorities, which suggests discriminatory reporting and increased surveillance for maltreatment in communities of color. A second important source of systemic disparity in treatment is that families of color are offered fewer in-home services that might prevent the placement of a child or adolescent in foster care. As a result, children of color are both more likely to be removed from a home and more likely to remain in foster placements longer without a permanent resolution.
Over the past two decades, Congress has gradually enacted statutory changes that better align the child welfare system with the developmental assets and challenges that adolescents face, including focusing attention on family reunification, prioritizing placement with relatives over strangers, and providing services for those adolescents aging out of foster care. These federal statutory changes are significant advances, but additional efforts are needed to ensure that all adolescents involved with the child welfare system have the opportunity to flourish. The committee’s recommendations center on providing services and supports for adolescents that differ from those provided to their younger counterparts within the child welfare system, focusing on adolescents’ need to be involved as partners in decisions affecting their housing, health and mental health, and education. The committee’s six key areas of recommendation are
RECOMMENDATION 8-1: Reduce racial/ethnic disparities in child welfare system involvement.
RECOMMENDATION 8-2: Promote broad uptake by the states of federal programs that promote resilience and positive outcomes for adolescents involved in the child welfare system.
RECOMMENDATION 8-3: Provide services to adolescents and their families in the child welfare system that are developmentally informed at the individual, program, and system levels.
RECOMMENDATION 8-4: Conduct research that reflects all types and ages of adolescents in the child welfare system.
RECOMMENDATION 8-5: Foster greater collaboration between the child welfare, juvenile justice, education, and health systems.
RECOMMENDATION 8-6: Provide developmentally appropriate services for adolescents who engage in noncriminal misconduct without justice-system involvement.
Recommendations for the Justice System
Over the past 15 years, advances in the science of adolescent development have had a substantial impact on juvenile justice reform and have also focused attention on the potential value of developmentally appropriate practices for older adolescents involved in the criminal justice system. Findings regarding adolescent brain development have highlighted the diminished culpability of adolescent offenders and their potential responsiveness to preventive interventions based on evidence-based risk- and needs-assessments.
While it is clear that a developmental approach to the juvenile justice system has been widely embraced by reformers and is having a discernible impact on law and practice in many states, progress across the country is uneven, and sustained effort and attention are needed to accelerate advances and to prevent an erosion of gains. Priority areas for reform within the juvenile justice system include the need for increased family engagement and greater attention to procedural fairness, including fairness in interactions with the police, legal representation for youth, and reduced use of juvenile fines and fees. Another reform priority is reducing the unwarranted harm to juveniles’ future well-being caused by justice-system involvement, including public disclosure of justice-system records, listing on sex offender registries, and solitary confinement.
Similar reform efforts recognizing the developmental needs of older adolescents and young adults are emerging within the criminal justice system, including reducing automatic transfers of juveniles to criminal courts based only on the charged offense, and creating developmentally informed correctional programs for young offenders. These efforts should be guided by the science of adolescent development and the core principles of a developmental approach.
Despite decades of attention under federal law, racial/ethnic disparities in police, prosecutorial, and judicial decision making in the juvenile justice and criminal justice systems persist, and in some contexts they are actually increasing. While the literature reflects continuing uncertainty about the relative contribution of differential offending, differential enforcement, and differential judicial processing, it is clear that the lack of progress in reducing disparities within the justice system has led to harmful outcomes for minority and other affected youth.
Previous National Academies’ reports on juvenile justice outlined recommendations for needed reforms to ensure that the juvenile justice system accounts for and attends to the developmental needs of youth. This committee reaffirms those recommendations, and offers several additional recommendations in five key areas:
RECOMMENDATION 9-1: Reduce disparities based on race, ethnicity, gender, ability status, and sexual orientation or gender identity and expression among adolescents involved in the justice system.
RECOMMENDATION 9-2: Ensure that youth maintain supportive relationships while involved in the justice system and receive appropriate guidance and counsel from legal professionals and caregivers.
RECOMMENDATION 9-3: Implement policies that aim to reduce harm to justice-involved youth in accordance with knowledge from developmental science.
RECOMMENDATION 9-4: Implement developmentally appropriate and fair policies and practices for adolescents involved in the criminal justice system.
RECOMMENDATION 9-5: For those youth in the custody of the justice system, ensure that policies and practices are implemented to prioritize the health and educational needs of adolescents and avoid causing harm.
Adolescence, spanning the years from the onset of puberty to adulthood, is a formative period when changes in cognition, affect, and interpersonal behavior occur alongside the most extensive neurobiological transitions since infancy, especially with respect to pubertal and brain development. These changes make it clear that adolescent brains are not best understood as simply “advanced” child brains or “immature” adult brains. Instead they
have evolved to meet the developmental needs of humans at this stage of life. Collectively, the pubertal, neurobiological, cognitive, and psychosocial changes occurring during adolescence mark this as a period of great opportunity for adolescents to flourish and thrive.
However, in the United States today many families lack adequate resources and neighborhood supports, leaving many adolescents at significant disadvantage during this critical period of development. To fail to address the sources of these disparities is to waste human capital: lower worker productivity, lost wages and employment, worse health and mental health, increased criminal justice involvement, and a drain on public support. These outcomes would reduce economic growth and exacerbate rising income inequality. Creating positive impact by improving opportunities for adolescents not only improves trajectories relevant to multiple outcomes, but also, by making use of high-impact, cost-effective interventions, it can counteract the effects of childhood stresses and deprivations and prevent negative outcomes in adulthood.
These realities also highlight a compelling scientific challenge. To understand how we can help all adolescents flourish, we need to connect two bodies of research: the deepened understanding of developmental processes needs to also encompass a richer understanding of the impact of the social environment. Achieving this will require a major commitment by our research establishment. Future research investments in adolescence should support efforts that (1) deepen our knowledge of the processes of adolescent development, (2) examine the socio-environmental contexts that offer opportunities for flourishing, and (3) understand and combat inequities that curtail the promise of adolescence for all youth.
Our society has a collective responsibility to build systems that support and promote positive adolescent development. These systems should reflect a rich understanding of the developmental needs of adolescents and a specific recognition of adolescence as a time of great opportunity to promote learning and discovery and to remediate past developmental challenges. Until society embraces this responsibility, the promise of adolescence will remain unfulfilled for millions of youth.