Adolescent Brain Development: Implications for Behavior

By Michelle K. Jetha and Sidney Segalowitz

This comprehensive yet brief overview of the adolescent human brain discusses how the brain develops during this critical period of life and how that development impacts decision-making and risk-taking behavior in the adolescent.

• This originated as a white paper requested by the Canadian government for a specific group looking to understand adolescent brain development in the context of adolescent behaviour
• The paper was not made available to the Canadian government outside of the specific task force that requested it nor to the general public

• Language: English
• Publisher: Academic Press
• Release date: Jul 24, 2012
• ISBN: 9780123979179

Michelle K. Jetha

Michelle Jetha is a research associate of the Brock University Centre for Lifespan Development Research, works in the Cognitive and Affective Neuroscience Lab, and teaches at McMaster and Brock Universities. She completed her PhD in 2007, examining electrophysiological responses to social and affective stimuli in individuals with schizophrenia or autism. She has published extensively on these topics, a major review of adolescent EEG/ERP development, and most recently on how shyness influences early brain responses to emotional face stimuli. Jetha completed postdoctoral work at Pennsylvania State University which focused on the identification of trait factors that predispose children to disruptive behavioral disorders. She is currently conducting research with adolescents in collaboration with a Niagara regional mental health agency. Her focus is translational neuroscience involving developmental psychopathology.

Book preview

Table of Contents

Cover image

Title page

Copyright

Preface

Introduction

Chapter 1. Structural Brain Development in Late Childhood, Adolescence, and Early Adulthood

1.1 Introduction

1.2 Anatomical Changes

1.3 Summary

Chapter 2. Connectivity

2.1 Changes in Networks Over Childhood, Adolescence, and Young Adulthood

2.2 How are Changes in Connectivity Related to Development in the Cognitive Domain?

2.3 Implications

Chapter 3. Social and Emotional Development

3.1 The Development of Social Information Processing

3.2 Models of Social Behavior

3.3 Aggression

3.4 Individual Differences in Social Behavior: A Personality Perspective

Chapter 4. How Genes and Environment Work Together to Influence Brain Growth and Behavior

4.1 Genetic Effects on Brain Growth

4.2 A Broad Range of Experiential Factors Influence Brain Development

4.3 Implications: The Bottom Line

Summary and Implications

Reference

Copyright

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First published 2012

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ISBN: 978-0-12-397916-2

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Preface

It is hard to exaggerate the degree to which research over the past two decades has been energized by the realization that adolescent brain growth is dynamic. A simple search of a leading online database (PubMed) with the code words brain development and adolescence yields over 5,000 refereed journal articles since the year 2000. In the past 20 years, social psychologists and neuroscientists have started to collaborate in a way that would have seemed, before this period, impossible or pointless. Before this time, their worldviews on how the mind works differed so much that such collaboration would have more likely ended in frustration than in fruitful scholarship. Today, through collaborative efforts and facilitated by new technologies, the field of developmental social neuroscience is well established and is grounded on the premise that the full understanding of social development can only come from the integration of multiple levels of analyses. We now have numerous journals whose titles include various combinations of social, cognitive, affective, and developmental neuroscience, with a great deal of emphasis on the adolescent period. It is a terrifically exciting time to be in this field.

In December of 2010, we were asked by the Ontario Ministry of Child and Youth Services to summarize and synthesize the research literature on adolescent brain development and the implications of this development for behavior, including the potential implications for public policies that concern adolescent welfare. We completed this project in April 2011 and have continued to think about the challenges that this task presented to us.

Pulling this broad field together has been useful to our own thinking concerning our research and teaching, and we have continued to find new research to add to our synthesis. As we gave community talks on the topic, we identified gaps in the published literature of material that was devoted to translating empirical research to a more readable form for individuals who are working with young people. This was not surprising considering how rapidly the field is advancing. On numerous occasions, we were asked to produce a readable, brief summary of research in the field, so that these findings would be readily available to healthcare practitioners, community workers, and parents. The requests also came from college and university instructors who wanted this information summarized in what could be a supplementary text, one that not only links the research to real-world issues but also provides the reader with some sense of the controversies in the field. With this online book, we have attempted to fill this gap. We aimed to provide an accessible overview of brain changes from childhood through adolescence and early adulthood with an emphasis on the implications for social and emotional behavior. We hope that our brief coverage of this biological perspective will shed new light for our readers on this creative, passionate, and often tumultuous period of development.

Integrating the research in the field has been a rewarding challenge. We would like to especially thank Allison Flynn Bowman for her invaluable help in searching out sources and arranging permissions for reproduction of figures. We would also like to thank the Ontario Ministry of Child and Youth Services for getting us started on this venture and giving us a free hand to deal with the task as we saw fit.

Michelle K. Jetha, Ph.D.

Sidney J. Segalowitz, Ph.D.

April 2012

Introduction

There’s been a great deal of emphasis in the 1990s on the critical importance of the first three years. I certainly applaud those efforts. But what happens sometimes when an area is emphasized so much is other areas are forgotten. And even though the first 3 years are important, so are the next 16. And the ages between 3 and 16, there’s still enormous dynamic activity happening in brain biology. I think that that might have been somewhat overlooked with the emphasis on the early years.

Jay Giedd-Chief, Unit on Brain Imaging, Child Psychiatry Branch, NIMH¹⁰⁶

As recently as the mid 1990s, the prevailing notion among neuroscientists was that the most important aspect of brain development ended by about 3 years of age. This assumption led to an explosion of research on early brain maturation with an emphasis on early life experiences, the importance of gene and environment interactions, and the central role of early relationships with caregivers. Since that time, with the advent of new imaging technologies and the work of developmental neuroscientists, we now know that the brain continues to organize, adapt, and change well beyond the early years, and, in some respects, over the full lifespan. The physical changes in the brain that occur during late childhood, adolescence, and into young adulthood are particularly dramatic and occur at all levels: molecular, cellular, anatomical, and functional.

These physical changes are accompanied by notable changes in social behavior. For example, preteens transition from being more dependent on caregivers to becoming independent young adults. There is also a shift from more family-oriented to more peer-oriented interactions, and an increase in the appeal of novelty and excitement, and the desire to explore and take risks. Such transitions are healthy and lead to opportunities to hone important social and behavioral skills that will be necessary for taking on adult roles and responsibilities. Unfortunately, they may also come with a cost. Adolescence is a time of increased drug use and unprotected sex, and the three highest causes of mortality in adolescents are accidents, homicides, and suicides.¹⁴³

This developmental period is also marked by variations in emotionality and in self-regulation. In adolescence, emotions become more intense, fluctuate more often and are more subject to extremes than those experienced by children and adults. Concurrent with these emotional changes are shifts in behavioral regulation. In childhood, behavioral regulation is more externally derived from the guidance and constraints put in place by parents and caregivers, whereas in adolescence there is an increasing need for self-regulation. The way in which changes in emotionality and self-regulation are negotiated will greatly influence how well the adolescent navigates through his/her expanding social world. How effectively preteens and adolescents learn to self-regulate impulses and emotions will influence not only decisions about participation in dangerous activities, but also vulnerability to psychopathology. This is especially important considering that the lifetime risk for the emergence of psychopathology peaks at age 14.¹⁵²

During the past 20 years, studies have accumulated that document the physical brain changes during the transition from childhood to adulthood, whereas numerous others have begun to pave the way for a more in-depth understanding of the functional significance of these changes. Can we explain notable social and emotional changes from a brain-based perspective? In the following chapters, we will provide a summary of findings from this exciting frontier in brain research. After a description of the dramatic changes in brain structure and connectivity over this period, we turn