the science of early childhood development

8/14/2019 the science of early childhood development

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he Science o

Early ChildhoodDevelopment

Closing the Gap BetweenWhat We Know and What We Do

National Scientic CouncilCenter on the Developing Child at Harvard University

www.developingchild.net


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Council MembersJack P. Shonko, M.D., ChairJulius B. Richmond FAMRI Proessoro Child Health and DevelopmentDirector, Center on the Developing Child,Harvard University

W. Tomas Boyce, M.D.Sunny Hill Health Centre/BC LeadershipChair in Child DevelopmentProessor, Graduate Studies and Medicine,University o British Columbia, Vancouver

Judy Cameron, Ph.D.Proessor o Psychiatry, University o PittsburghSenior Scientist, Oregon NationalPrimate Research CenterProessor o Behavioral Neuroscienceand Obstetrics & Gynecology,Oregon Health and Science University

Greg Duncan, Ph.D.Edwina S. arry Proessor o HumanDevelopment and Social PolicyFaculty Fellow, Institute or Policy Research,Northwestern University

Nathan A. Fox, Ph.D.Proessor o Human Development,University o Maryland College Park

William Greenough, Ph.D.Swanlund Proessor o Psychology, Psychiatry,and Cell and Developmental BiologyDirector, Center or Advanced Study atUniversity o Illinois, Urbana-Champaign

Megan Gunnar, Ph.D.Regents Proessor and DistinguishedMcKnight University Proessor,Institute o Child Development,University o Minnesota

Eric Knudsen, Ph.D.Edward C. and Amy H. SewallProessor o Neurobiology,Stanord University School o Medicine

Pat Levitt, Ph.D.Proessor o PharmacologyAnnette Schaer Eskind Chair andDirector, Kennedy Center or Researchon Human Development,

Vanderbilt University

Betsy Lozo, M.D.Proessor o Pediatrics, University oMichigan Medical SchoolResearch Proessor, Center orHuman Growth and Development,University o Michigan

Charles A. Nelson, Ph.D.Richard David Scott Chair in PediatricDevelopmental Medicine Research,Childrens Hospital BostonProessor o Pediatrics,Harvard Medical School

Deborah Phillips, Ph.D.Proessor o Psychology and AssociatedFaculty, Public Policy InstituteCo-Director, Research Centeron Children in the U.S.,Georgetown University

Ross Tompson, Ph.D.Proessor o Psychology,University o Caliornia, Davis

Contributing Members

Susan Nall BalesPresident, FrameWorks Institute

James J. Heckman, Ph.D.Henry Schultz DistinguishedService Proessor o Economics,University o Chicago

Bruce S. McEwen, Ph.D.Alred E. Mirsky ProessorHead, Harold and Margaret Milliken HatchLaboratory o Neuroendocrinology,Te Rockeeller University

Arthur J. Rolnick, Ph.D.

Senior Vice President and Director o Research,Federal Reserve Bank o Minneapolis

Council PartnersTe FrameWorks Institute

Te Johnson & Johnson Pediatric Institute

Te National Conerence o State Legislatures

Council SponsorsTe Buett Early Childhood Fund

Te Pierre and Pamela Omidyar Fund

Te John D. and Catherine . MacArthur Foundation

Suggested citation: Te Science of Early Childhood Development. (2007)National Scientic Council on the Developing Child. http://www.developingchild.net

January 2007 naTIOnaL SCIEnTIFIC COunCIL On THE DEVELOPInG CHILD


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he uture o any societydepends on its ability to oster the health and well-being o the next

generation. Stated simply, todays children will become tomorrows citizens, workers, and par-

ents. When we invest wisely in children and amilies, the next generation will pay that back

through a lietime o productivity and responsible citizenship. When we ail to provide chil-

dren with what they need to build a strong oundation or healthy and productive lives, we put ouruture prosperity and security at risk.

wo recent developments have stimulated growing public discussion about

the right balance between individual and shared responsibility or that strong

oundation. Te rst is the explosion o research in neurobiology that clari-

es the extent to which the interaction between genetics and early experience

literally shapes brain architecture. Te second is the increasingly recognized

need or a highly skilled workorce and healthy adult population to conront

the growing challenges o global economic competition and the rising costs o

Social Security, Medicare, and Medicaid or the aging baby boomers.

In an eort to identiy those aspects o development that are accepted broad-

ly by the scientic community, the National Scientic Council, based at the

Center on the Developing Child at Harvard University, brought together

several o the nations leading neuroscientists, developmental psychologists,

pediatricians, and economists. Tis document presents their critical review

o the existing literatures in their elds and a consensus about what we now

know about development in the early childhood years. Te objective o the Council is to move beyond

the publics ascination with the latest study and ocus on the cumulative knowledge o decades o re-

search that has been subjected to rigorous and continuous peer review. Te goal o this document is to

help the public and its policy makers understand the core principles o that body o work that are now

suciently accepted across the scientic community to warrant public action.

It is our hope and belie that better public understanding o the rapidly growing science o early

childhood and early brain development can provide a powerul impetus or the design and implementa-

tion o policies and programs that could make a signicant dierence in the lives o all children. With-out that understanding, investments that could generate signicant returns or all o society stand therisk o being rejected or undermined. Tus, there is a compelling need or scientists to share with the

public and its representatives an objective basis or choosing wisely among competing demands on lim-

ited resources.

Tis paper is designed to provide a ramework within which this complex challenge can be addressed

most eectively. Its goal is to promote an understanding o the basic science o early childhood devel-

opment, including its underlying neurobiology, to inorm both public and private sector investment in

young children and their amilies. o this end, the paper presents a set o core developmental concepts

that have emerged rom decades o rigorous research in neurobiology, developmental psychology, and

the economics o human capital ormation, and considers their implications or a range o issues in pol-

icy and practice.

Core Concepts of Development Child development is a oundation or community development and economic development, as capable

children become the oundation o a prosperous and sustainable society.

Brains are built over time.

Te interactive infuences o genes and experience literally shape the architecture o the developing brain,

and the active ingredient is the serve and return nature o childrens engagement in relationships with

their parents and other caregivers in their amily or community.

Executive Summary


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Both brain architecture and developing abilities are built rom the bottom up, with simple circuits

and skills providing the scaolding or more advanced circuits and skills over time.

oxic stress in early childhood is associated with persistent eects on the nervous system and stress

hormone systems that can damage developing brain architecture and lead to lielong problems in

learning, behavior, and both physical and mental health.

Creating the right conditions or early childhood development is likely to be more eective and less

costly than addressing problems at a later age.

Implications for Policy and Practice Policy initiatives that promote supportive relationships and rich

learning opportunities or young children create a strong ounda-

tion or higher school achievement ollowed by greater productivity

in the workplace and solid citizenship in the community.

Substantial progress toward this goal can be achieved by assuring

growth-promoting experiences both at home and in community-

based settings, through a range o parent education, amily support,

early care and education, preschool, and intervention services.

When parents, inormal community programs, and proessionally

staed early childhood services pay attention to young childrens

emotional and social needs, as well as to their mastery o literacy and

cognitive skills, they have maximum impact on the development o

sturdy brain architecture and preparation or success in school.

When basic health and early childhood programs monitor the de-

velopment o all children, problems that require attention can be

identied in a timely ashion and intervention can be provided.

Te basic principles o neuroscience and the technology o human

skill ormation indicate that later remediation or highly vulner-

able children will produce less avorable outcomes and cost more

than appropriate intervention at a younger age.

Te essence o quality in early childhood services is embodied in the expertise and skills o the sta

and in their capacity to build positive relationships with young children. Te striking shortage o well-

trained personnel in the eld today indicates that substantial investments in training, recruiting, com-

pensating, and retaining a high quality workorce must be a top priority.

Responsible investments in services or young children and their amilies ocus on benets relative

to cost. Inexpensive services that do not meet quality standards are a waste o money. Stated simply,

sound policies seek maximum value rather than minimal cost.

Te need to address signicant inequalities in opportunity, beginning in the earliest years o lie, isboth a undamental moral responsibility and a critical investment in our nations social and economic u-

ture. Tus, the time has come to close the gap between what we know (rom systematic scientic inquiry

across a broad range o disciplines) and what we do (through both public and private sector policies and

practices) to promote the healthy development o all young children. Te science o early childhood de-

velopment can provide a powerul ramework or inorming sound choices among alternative priorities

and or building consensus around a shared plan o action. Te well-being o our nations children and

the security o its uture would be well-served by such wise choices and concerted commitment.


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he uture o any societydepends on its ability to oster the health and well-being o the nextgeneration. Stated simply, todays children will become tomorrows citizens, workers, and

parents. When we ail to provide children with what they need to build a strong ounda-

tion or healthy and productive lives, we

put our uture prosperity and security at risk.

Science has a lot to oer about how we as a commu-

nity can use our collective resources most eectively and

eciently to build that strong oundation. When we in-

vest wisely in children and amilies, the next generation

will pay that back through a lietime o productivity and

responsible citizenship. When we do not make wise in-

vestments in the earliest years, we will all pay the con-

siderable costs o greater numbers o school-aged chil-

dren who need special education and more adults who

are under-employable, unemployable, or incarcerated.

wo recent developments have stimulated growing

public discussion about the right balance between in-

dividual and shared responsibility or child well-being.

Te rst is the explosion o research in neuroscience

and other developmental sciences that highlights the

extent to which the interaction between genetics and

early experience creates either a sturdy or weak oundation or all the learning, behavior, and health that

ollow. Te second is the increasingly recognized need or a highly skilled workorce and healthy adult

population to conront the growing challenges o global economic competition and the rising costs oSocial Security, Medicare, and Medicaid or the aging baby boomers.

Most policy makers who ace decisions among competing actions lack both the time and means to

secure sound scientic advice about which investments oer the greatest potential value and what pro-

gram elements are critical to their eectiveness. Tose same policy makers must explain their decisions

to business executives and civic leaders who hold a wide range o belies about child-rearing and de-

velopmental infuences. Without better public under-

standing o the science o early childhood and brain

development, policies and programs that could make

a signicant dierence in the lives o children and all

o society stand the risk o being rejected or under-

mined. Tus, there is a compelling need to educate

the public and its representatives about how to choose

wisely among competing demands.

For some, the most important decisions ocus on the

allocation o resources among alternative approaches

dened by need (e.g., universal versus targeted invest-

ments) or age (e.g., pre-K or our-year-olds versus parent support programs beginning at birth). Oth-

ers move quickly to questions about the relative merits o dierent program models. Some are interested

primarily in the results o benet-cost analyses. Others view the reduction o inequalities in opportunity

When we invest wisely inchildren and families, the next

generation will pay that backthrough a lifetime of productivityand responsible citizenship.

he Science oEarly Childhood Development


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as a moral imperative. All are united in the responsibility

to assure that limited resources are invested wisely.

Regardless o the questions, it is essential that the an-

swers be grounded in accurate scientic knowledge where

it is available and sound proessional judgment when it is

needed. Tis is particularly important in the ace o inevi-

table debates over alternative interpretations o the moun-tains o program evaluation data generated in a policy en-

vironment characterized by ideological dierences about

the means and ends o raising young children.

In October 2000, the Institute o Medicine and Na-

tional Research Council o the National Academy o Sci-

ences released a report entitled From Neurons to Neighbor-

hoods: Te Science of Early Childhood Development. Te

nal paragraph o that 588-page report presented a com-

pelling challenge:

Te charge to this committee was to blend the knowledge

and insights of a broad range of disciplines to generate an in-tegrated science of early childhood development. Te charge to society is to blend the skepticism of a scientist,

the passion of an advocate, the pragmatism of a policy maker, the creativity of a practitioner, and the devotion

of a parentand to use existing knowledge to ensure both a decent quality of life for all of our children and

a promising future for the nation.

Tis paper is designed to provide a ramework within which this complex charge can be addressed

most eectively. Its goal is to promote an understanding o the basic science o early childhood devel-

opment, including its underlying neurobiology, to inorm both public and private sector investment in

young children and their amilies. o this end, the paper presents a set o core developmental concepts

that have emerged rom decades o rigorous research in neuroscience, developmental psychology, and

the economics o human capital ormationand that have survived a rigorous process o debate among

the members o the National Scientic Council on the Developing Child about what science can tell usabout brain architecture and the oundations o learning, behavior, and health.

Core Concepts of Development

Concept :Child development is a oundation or community develop-ment and economic development, as capable children become the oundation o a prosperous and

sustainable society.

Te early development o cognitive skills, emotional well-being, social competence, and sound physical

and mental health builds a strong oundation or success well into the adult years. Beyond their short-

term importance or positive school achievement, these abilities are critical prerequisites or economic

productivity and responsible citizenship throughout lie. All aspects o adult human capital, rom workorce skills to cooperative and lawul behavior, build on capacities that are developed during childhood,

beginning at birth.

Implications or Policy and Practice

Policy initiatives that promote supportive relationships and rich learning opportunities or young children

create a strong oundation or higher school achievement ollowed by greater productivity in the work-

place and solid citizenship in the community throughout the adult years. Tus, current calls or greater

emphasis on early literacy must not diminish the importance o attention to other essential capacities,


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such as initiative, sel-condence, and persistence in learning, as well as the ability to work cooperatively

and resolve confict with peersall o which are core characteristics o students in a successul school, citi-

zens in a healthy community, and the workorce o a pros-

perous nation.

All o society would benet rom a coordinated eort to

reduce signicant inequalities in the skills o young chil-

dren at school entry. Substantial progress toward this goalcan be achieved by assuring high quality early learning ex-

periences both at home and in community-based settings,

through a range o parent education, amily support, early

care and education, preschool, and intervention services.

Tis calls or a long-term investment by all segments o

societyincluding the business community, private philanthropy, both aith-based and secular volun-

tary organizations, proessional associations, and government at all levelsto work together to strength-

en amilies, educate mothers and athers, and provide proessional assistance or those young children

and their parents who need help. In act, the uture vitality o the institutions that each these sectors rep-

resent will depend on the wisdom o their investment, as todays children either take up societys impor-

tant work and roles as adults or are ill-prepared and unable to do so. Eective early childhood policies and practices will not eliminate all social and economic inequalities.

However, when successul interventions are ollowed by continuing investments throughout the child-

hood years, they increase the odds that many more children will grow up to be adults who contribute pos-

itively to their communities and raise healthy and competent children themselves, while many ewer will

end up on public assistance or in jail.

Concept :Brains are built over time.Te basic architecture o the brain is constructed through an ongoing

process that begins beore birth and continues into adulthood. Like

the construction o a home, the building process begins with laying the

oundation, raming the rooms, and wiring the electrical system in apredictable sequence, and it continues with the incorporation o dis-

tinctive eatures that refect increasing individuality over time. Brain

architecture is built over a succession o sensitive periods, each o

which is associated with the ormation o specic circuits that are asso-

ciated with specic abilities. Te development o increasingly complex

skills and their underlying circuits builds on the circuits and skills that

were ormed earlier. Trough this process, early experiences create a

oundation or lielong learning, behavior, and both physical and men-

tal health. A strong oundation in the early years increases the prob-

ability o positive outcomes and a weak oundation increases the odds

o later diculties.


When systems are put in place to monitor the development o all children continuously over time,

problems that require attention can be identied early and appropriate responses can be made. Tis can

be accomplished by appropriately trained physicians, nurse practitioners, or developmental specialists

within the context o regular health care, as well as through the ongoing observations o skilled provid-

ers o early care and education. Fully meeting this goal requires prenatal care or all pregnant women

and sustained access to a consistent source o primary health care or all children.

All aspects of adult humancapital, from work force skills

to cooperative and lawfulbehavior, build on capacities

that are developed during

childhood, beginning at birth.


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Environmental protection policies need

continuous updating and enorcement

i they are to succeed in reducing prena-

tal and early childhood exposures to sub-

stances that have clearly documented tox-

ic eects on the immature brain. Tese

include mercury in sh, lead in soil, andorganophosphates in insecticides, among

many others.

Te act that etal exposure to alcohol is

the leading preventable cause o mental

retardation in the United States directs

our attention to the need or new and cre-

ative eorts to reduce alcohol consump-

tion during pregnancy.

Concept : Te interactive inuences o genes and experience literally

shape the architecture o the developing brain, and the active ingredient is the serve and returnnature o childrens engagement in relationships with their parents and other caregivers in their

amily or community.

Te architecture o the brain is composed o highly integrated sets o neural circuits (i.e., connections

among brain cells) that are wired under the continuous and mutual infuences o both genetics and

environment. Genes determine when specic brain circuits are ormed and individual experiences then

shape how that ormation unolds. Tis developmental process is ueled by a sel-initiated, inborn drive

toward competence that is an essential characteristic o human nature. Appropriate sensory input (e.g.,

through hearing and vision) and stable, responsive relationships build healthy brain architecture that

provides a strong oundation or lielong learning, behavior, and health. Te most important relation-

ships begin in the amily but oten also involve other adults who play important roles in the lives o

young children, including providers o early care and education.

What scientists reer to as interaction, mutuality, and reciprocity can be understood as comparable

to the process o serve and return in games such as tennis and volleyball. In early childhood develop-

ment, serve and return happens when young children naturally reach out or interaction through bab-

bling, acial expressions, words, gestures, and cries, and adults respond by getting in sync and doing the

same kind o vocalizing and gesturing back at them, and the process continues back and orth. Another

important aspect o the serve and return notion o interaction is that it works best when it is embedded

in an ongoing relationship between a child and an adult who is responsive to the childs own unique in-

dividuality. Decades o research tell us that mutually rewarding interactions are essential prerequisites

or the development o healthy brain circuits and increasingly complex skills.


Healthy communities oster the development o healthy children through the inormal support that ami-lies provide or each other. When parents are inexperienced in child-rearing or overwhelmed by economic

insecurity or threatening community conditions, eective parent education and amily support programs

can help them sustain the kinds o growth-promoting experiences that build child competence and

shape healthy brain architecture. When inormal supports and community programs are not sucient,

proessional assistance can make an important dierence in preventing the ormation o aulty brain cir-

cuits and the developmental problems that ollow. However, proessionals with appropriate expertise are

relatively limited in number, and their availability will require signicant investment in specialized training,


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particularly in the domains o maternal and early child-

hood mental health.

Business executives, civic leaders, and government o-

cials at all levels should work together to develop bet-

ter private sector and public policies to provide parents

with more viable choices about how to balance their

work and parenting responsibilities ater the birth oa baby or adoption o a child. During early inancy,

when parent-child bonding and emerging attachments are so important, there is a pressing need to strike

a better balance between options that support parents to care or their babies at home and those that pro-

vide aordable, quality child care or parents who return to work or attend school. Tis also calls our at-

tention to the need or a more child-oriented perspective on the implications o mandated employment

or mothers o very young children who receive welare support.

Te important infuence o positive relationships in shaping the architecture o the developing brain

indicates that all o society would benet rom better trained personnel in early child care settings, as

well as reduced sta turnover rates which currently undermine the relationships that young children

have with the adults who provide much o their daily care. Policy makers should examine the poten-

tial impact o alternative strategies or increasing the retention o qualied sta, such as competitivesalaries and benets, opportunities or career advancement linked to additional education, and greater

respect or their work as a valued proession. Promising initiatives can be modeled ater the successul

investments made by the U.S. Department o Deense, which has a very high quality system o early

care and education.

Concept : Both brain architecture and developing abilities are builtrom the bottom up, with simple circuits and skills providing the scaolding or more advanced

circuits and skills over time.

Brain circuits that process basic inormation are wired earlier than those that process more complex in-

ormation. Higher level circuits build on lower level circuits, and adaptation at higher levels is more

dicult i lower level circuitswere not wired properly. Parallel

to the construction o brain cir-

cuits, increasingly complex skills

build on the more basic, oun-

dational capabilities that precede

them. For example, the ability

to understand and then say the

names o objects depends upon

earlier development o the ca-

pacity to dierentiate and repro-

duce the sounds o ones native

language. And the circuits that

underlie the ability to put words

together to speak in phrases orm

a oundation or the subsequent

mastery o reading a written sen-

tence in a book. Stated in simple

terms, circuits build on circuits

and skill begets skill.

Increasingly complex skills

build on the more basic,

foundational capabilities

that precede them.


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Policy makers should consider increasing the availability o parent education and amily support programs

that have been demonstrated to be eective. Tese services should begin soon ater birth or mothers and

athers with limited education to help them create a home environment that provides the kind o rich

language exposure, positive social interactions, and early literacy experiences that increase the probabil-

ity that their child will enter school with the skills needed to

succeed. When children are born under signicantly adversecircumstances, immediate intervention is warranted, includ-

ing prenatal support services where easible. Eective programs

can be provided through voluntary associations, community-

based organizations, and employer-sponsored initiatives, as

well as through government-unded services. Evidence-based

supports that are provided earlier rather than later will have the

greatest impact, as they help establish healthy brain architec-

ture during the period when lower-level circuits are being con-

structed (even beore birth), thereby creating a strong ounda-

tion on which higher-level skills can be built.

o help children with developmental impairments master the adaptive skills needed to real-ize their ull potential, outreach eorts should be increased to enroll all eligible children in early

intervention programs. When positive changes in development are promoted through interventions at a

young age, they help build a sturdier oundation or the later achievement o higher level abilities. Tis

underscores the urgent need to identiy sensory impairments as soon ater birth as possible, so that cor-

rective devices (e.g., hearing aids and eyeglasses) as well as appropriate habilitative services can be pro-

vided during the time that basic brain architecture is being established.

Concept : Cognitive, emotional, and socialcapabilities are inextricably intertwined throughout the lie

course.

Te brain is a highly integrated organ and its multiple unctionsoperate in a richly coordinated ashion. Emotional well-being

and social competence provide a strong oundation or emerg-

ing cognitive abilities, and together they are the bricks and mor-

tar that comprise the oundation o human development. Tus,

oral language acquisition depends not only on adequate hear-

ing, the ability to dierentiate sounds, and the capacity to link

meaning to specic words, but also on the ability to concen-

trate, pay attention, and engage in meaningul social interaction.

Furthermore, the emotional health, social skills, and cognitive-

linguistic capacities that emerge in the early years are all impor-

tant prerequisites or success in school and later in the workplace

and community. Brain architecture and the immune system alsointeract as they mature, which infuences all domains o devel-

opment and health.


When parents, inormal community supports, and proessionally staed early childhood care and educa-

tion programs all pay attention to young childrens emotional and social needs as well as to their mastery o

literacy and cognitive skills, they have maximum impact on the development o sturdy brain architecture.

Emotional well-being,

social competence, and

cognitive abilities togetherare the bricks and mortar that

comprise the foundation ofhuman development.


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Conversely, preschool policies and programs that place disproportionate emphasis on didactic approaches

to academic skills are less likely to prepare young children to succeed in school than experiences that em-

bed the promotion o literacy and numeracy in a rich environment o age-appropriate social interaction.

Te science o early childhood and early brain development clearly indicates that state and local ocials

should support the implementation o both child care standards and preschool curricula that promote a

balanced and developmentally appropriate approach to the whole child.

Parents, child care providers, and early educa-tors who are seeking help to manage problem-

atic behavior in young children warrant serious

attention. With increasing numbers o chil-

dren being expelled rom preschool programs

and/or treated with drugs, greater investments

are needed to conront the serious shortage o

proessionals who are qualied to address the

behavioral and mental health needs o inants,

toddlers, and preschoolers. Expanded opportu-

nities or proessional training, stronger incen-

tives or clinicians to work with young children

and their parents, and the promotion o con-

sulting relationships among early childhood

mental health experts, child care providers, and

preschool teachers would provide important

rst steps toward closing the gap between what

we know and what we do to deal with dicult behavior and prevent more serious mental health problems

in the earliest years o lie.

Concept :oxic stress in early childhood is associated with persistenteects on the nervous system and stress hormone systems that can damage developing brain archi-

tecture and lead to lielong problems in learning, behavior, and both physical and mental health.

Activation o the bodys stress management systems produces a variety o physiological reactions. Tese

include an increase in heart rate, rise in blood pressure, and elevated levels o stress hormones (e.g., cor-

tisol) and proteins associated with infammation (e.g., cytokines). Such responses prepare the body to

deal with threat (i.e., ght or fight) and are essential to survival. Healthy development depends on

the capacity o these systems to ramp up rapidly in the ace o stress as well as their ability to return to

baseline when the threat has been mastered. When these physiological responses remain activated at

high levels over a signicant period o time, they can have adverse eects. Most prominent among these

are the consequences o persistently elevated cortisol levels, which can literally be toxic to developing

brain architecture.

Te experience o stress in early childhood can be either growth-promoting or seriously damaging,

depending on the intensity and duration o the experience, individual dierences in childrens physi-

ological responsiveness to stress, and the extent to which a supportive adult is available to provide in-dividualized support to help the child deal with adversity. Tis can be understood within the context

o three dierent kinds o stress, which lead to dierent outcomes.

Te rst, called positive stress, is associated with moderate, short-lived physiological responses, such

as brie increases in heart rate and blood pressure or mild elevations in cortisol or cytokine levels. Pre-

cipitants include a wide variety o normal early childhood experiences, such as the challenges o meet-

ing new people, dealing with rustration, mastering separation, getting an immunization, and coping

with adult limit-setting or discipline. Positive stress is an important and necessary aspect o healthy


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0 www.developingchild.net

development that occurs in the context o stable and supportive relationships, which help to bring lev-

els o cortisol and other stress hormones back within a normal range and assist the child to develop a

sense o mastery and sel control.

Te second kind o stress experience, called tolera-

ble stress, is associated with physiological respons-

es that could disrupt brain architecture, but are

relieved by supportive relationships that acilitateadaptive coping and thereby restore heart rate and

stress hormone levels to their baseline. Precipitants

include signicant threats, such as the death or se-

rious illness o a loved one, a rightening injury,

parent divorce, a natural disaster (such as Hurri-

cane Katrina), or an act o terrorism (such as 9-11).

Tese kinds o experiences could have long term

consequences but they are tolerable when they oc-

cur in a time-limited period in which supportive

adults protect the child by reducing the stressul

experience, thereby giving the brain an opportuni-

ty to recover rom the potentially damaging eects

o an overactive stress management system.

Te third and most threatening kind o stress experience, called toxic stress, is associated with strong and

prolonged activation o the bodys stress management systems in the absence o the buering protection o

adult support. Precipitants include extreme poverty in conjunction with continuous amily chaos, recur-

rent physical or emotional abuse, chronic neglect, severe and enduring maternal depression, persistent pa-

rental substance abuse, or repeated exposure to violence in the community or within the amily. Te essen-

tial eature o toxic stress is the absence o consistent, supportive relationships to help the child cope and

thereby bring the physiological response to threat back to baseline. In such circumstances, persistent eleva-

tions o stress hormones and altered levels o key brain chemi-

cals produce an internal physiological state that disrupts the ar-

chitecture o the developing brain and can lead to diculties

in learning, memory, and sel-regulation. Continuous stimula-

tion o the stress response system also can aect the immune

system and other metabolic regulatory mechanisms, leading to

a permanently lower threshold or their activation throughout

lie. As a result, children who experience toxic stress in early

childhood may develop a lietime o greater susceptibility to stress-related physical illnesses (such as cardio-

vascular disease, hypertension, and diabetes) as well as mental health problems (such as depression, anxiety

disorders, and substance abuse). Tey also are more likely to exhibit health-damaging behaviors and adult

liestyles that undermine well-being.

Implications or Policy and Practice Policy makers who administer early intervention programs should update their eligibility criteria, based

on new brain research, and actively enroll inants and toddlers who are experiencing toxic stress or

either preventive or therapeutic services, as needed. wo groups o children and amilies already known

to public agencies are prime candidates or assessment. Te rst (which is currently mandated or reer-

ral by new ederal legislation) includes all young children reerred to the child welare department or

evaluation o suspected abuse or neglect. When circumstances require removal o a child rom his or her

home, it is especially critical that policies be in place and implemented consistently to make sure that the

Stress in early childhood canbe either growth-promoting

or seriously damaging.


13/16


establishment o a nurturing relationship with a new primary caregiver is given the highest priority. Te

second group that warrants closer attention is young children o mothers supported by welare who have

reached their time limits or public assistance and

are unable to secure stable employment. Eective

developmental intervention or both groups will

require expanded access to child and adult mental

health services, which are already burdened by de-mands that ar exceed their capacity.

Greater attention should be directed toward ma-

ternal depression, not only because it is a common

adult mental health problem but also because it is a

threat to the health and well-being o a young child. Te prevention o developmental impairments in

children o depressed mothers requires prompt diagnosis and specialized treatment o both the mother

and the mother-child relationship. Tese ndings direct our attention to the need or early detection o

maternal depression in pediatric oces and in all programs that serve very young children, as well as the

need or expanded clinical services that ocus on the mother and child together.

When accessible and aordable mental health services are available, they put a preventive system in place

that catches children beore they all. Programs that target vulnerable young children within a amily-centered model can be particularly eective, but the current gap between the supply and demand or

skilled personnel requires a major investment in proessional development. Te costs o increased train-

ing and expanded services in early childhood mental health are substantial, but the money saved by not

treating emotional problems in

early childhood is likely to be

modest in comparison to the

greater long-term costs o seri-

ous adult mental illness and/or

criminal behavior.

Generally speaking, policies

that ocus on the delivery oevidence-based services or

the most vulnerable young

children will achieve greater

nancial return than services

or children at lesser risk. o

this end, issues o quality and

cost must be viewed in the

context o what a program is

expected to do. Programs or

amilies coping with severe

depression, substance abuse,

or violence must be staed

by skilled clinicians who re-

quire higher compensation

and smaller case loads than

basic supportive services or inexperienced mothers. When program resources match the needs o the

children and amilies they are set up to serve, they can be very eective. When services are asked to

address needs that are beyond their capacity to meet, they are likely to have little impact and are there-

ore too expensive, despite their low cost.

The essential feature of

toxic stress is the absence

of consistent, supportiverelationships to help the

child cope.


14/16


Concept : Creating the right conditionsor early childhood developmentis likely to be more eective and less costly than addressing problems at a later age.

As the maturing brain becomes more specialized to assume

more complex unctions, it is less capable o reorganizing and

adapting to new or unexpected challenges. Once a circuit is

wired, it stabilizes with age, making it increasingly di-

cult to alter. Scientists use the term plasticity to reer tothe capacity o the brain to change. Plasticity is maximal in

early childhood and decreases with age. Although windows

o opportunity or skill development and behavioral adap-

tation remain open or many years, trying to change behav-

ior or build new skills on a oundation o brain circuits that

were not wired properly when they were rst ormed requires

more work and is more expensive. For the brain, this means

that greater amounts o physiological energy are needed to

compensate or circuits that do not perorm in an expected

ashion. For society, this means that remedial education, clin-

ical treatment, and other proessional interventions are more

costly than the provision o nurturing, protective relation-

ships and appropriate learning experiences earlier in lie. Stat-

ed simply, getting things right the rst time is more ecient

and ultimately more eective than trying to x them later.


Tese ndings direct our attention to the importance o inormal amily support and ormal preventive

services (when needed) or vulnerable children beore they exhibit signicant problems in behavior or de-

velopment. When policy makers assure that all young children who are at high risk or poor outcomes are

enrolled in high quality programs whose eectiveness has been documented, the returns are ar greater

than those achieved when only a subgroup o eligible children are served. At the same time, the extent

to which some early concerns may be sel-correcting maturational delays underscores the need to avoidpremature labelling o vulnerable children and amilies who could benet rom early assistance.

Te basic principles o neuroscience and the process o human skill ormation indicate that early in-

tervention or the most vulnerable children will generate the greatest payback. Although the large

number o children and amilies who could benet rom additional assistance will require signi-

cant increases in unding, extensive research indicates

that investment in high quality interventions will gen-

erate substantial uture returns through increased taxes

paid by more productive adults and signicant reduc-

tions in public expenditures or special education, grade

retention, welare assistance, and incarceration. Stated

simply, the largest returns will be realized rom eectiveservices or the neediest children and amilies well beore

they enter school.

Research indicates that policy makers can achieve greater return on investments in early childhood educa-

tion or children rom amilies with low incomes and limited parent education than rom remedial pro-

grams or adults with limited workorce skills. In act, long-term studies show that model programs or

three- and our-year-olds living in poverty can produce benet-cost ratios as high as 17:1 and annualized

internal rates o return o 18% over 35 years, with most o the benets rom these investments accruing to

Getting things right therst time is more efcient and

ultimately more effective

than trying to x them later.


15/16


the general public. While it is not realistic to assume that all scaled-up early childhood programs will pro-

vide such handsome returns, it is likely that benet-cost ratios still will be considerably greater than 1:1.

Te essence o quality in early childhood services is embodied in the expertise, skills, and relationship-

building capacities o their sta. Te striking imbalance between the supply and demand or well-trained

personnel in the eld today indicates that substantial investments in training, recruiting, compensating,

and retaining a high quality workorce must be a top priority or society.

Responsible investments in services or young children and their amilies ocus on benets relative tocost. Inexpensive services that do not meet quality standards are a waste o money. Stated simply, sound

policies seek maximum value rather than minimal cost.

Concluding ToughtsDecades o rigorous science and centuries o common sense all converge on the core principles articulat-

ed in this paper. Within this context, the time has come to begin to close the gap between what we know

(rom systematic scientic inquiry across a broad range o disciplines) and what we do (through both

public and private sector policies and practices) to pro-

mote the healthy development o all young children.

Te need to address signicant inequalities in op-portunity, beginning in the earliest years o lie, is both

a undamental moral responsibility and a critical in-

vestment in our nations social and economic uture.

As such, it is a compelling task that calls or broad, bi-

partisan collaboration. And yet, debate in the policy

arena oten highlights ideological dierences and value

conficts more than it seeks common interest. In this

context, the science o early childhood development

can provide a values-neutral ramework or inorming

choices among alternative priorities and or building

consensus around a shared plan o action. Te well-being o our nations children and the security o our

collective uture would be well-served by such wise

choices and concerted commitment.

It is in this spirit that we, as scientists, oer this pa-

per as a way to share what we know about how brain ar-

chitecture is constructed and competence is built over

time, beginning in the earliest years o lie. We trust that

the content o this document will inorm the important

work o citizens and policy makers to support amilies

and communities in promoting the healthy develop-

ment o young children, just as it will serve as a ounda-

tion on which the next generation o scientic knowl-

edge will be built.


16/16

Selected Backround Readings

From the National Academy o SciencesNational Research Council and Institute o Medicine: From Neurons to Neighborhoods: Te Science ofEarly Childhood Development. Committee on Integrating the Science o Early Childhood Development,Shonko J., Phillips D. (eds.). Board on Children, Youth, and Families, Commission on Behavioral andSocial Sciences and Education. Washington, DC, National Academy Press. 2000.

From the National Scientifc Councilon the Developing ChildKnudsen, E., Heckman, J., Cameron, J., Shonko, J.: Economic, Neurobiological and BehavioralPerspectives on Building Americas Future Workorce. Proceedings o the National Academy o Sciences2006; 103: 10155-10162.

Young Children Develop in an Environment o Relationships . (2004)National Scientic Council on the Developing Child, Working Paper No.1http://developingchild.net/pubs/wp-abstracts/wp1.html

Childrens Emotional Development is Built into the Architecture o their Brain. (2004)National Scientic Council on the Developing Child, Working Paper No. 2http://developingchild.net/pubs/wp-abstracts/wp2.html

Excessive Stress Disrupts the Architecture o the Developing Brain. (2005)National Scientic Council on the Developing Child, Working Paper No. 3http://developingchild.net/pubs/wp-abstracts/wp3.html

Early Exposure to oxic Substances Damages Brain Architecture. (2006)National Scientic Council on the Developing Child, Working Paper No. 4http://developingchild.net/pubs/wp-abstracts/wp4.html

National Scientic Councilon the Developing Child

Center on the Developing Childat Harvard University

50 Church St., 4th Floor, Cambridge, MA 02138

617-496-2070 www.developingchild.net

the science of early childhood development

Documents