The Teen Brain: Still Under 

ConStrUCtion

NATIONAL INSTITUTE OF MENTAL HEALTH
One of the ways that 

scientists have searched for the 

causes of mental illness is by studying 

the development of the brain from 

birth to adulthood. Powerful new 

technologies have enabled them to 

track the growth of the brain 

and to investigate the 

connections between brain 

function, development, 

and behavior.

The research has turned up some surprises, among them 

the discovery of striking changes taking place during the 

teen years. These findings have altered long-held assumptions about the timing of brain maturation. In key ways, the 

brain doesn’t look like that of an adult until the early 20s. 

An understanding of how the brain of an adolescent is 

changing may help explain a puzzling contradiction of 

adolescence: young people at this age are close to a lifelong 

peak of physical health, strength, and mental capacity, and 

yet, for some, this can be a hazardous age. Mortality rates 

jump between early and late adolescence. Rates of death by 

injury between ages 15 to 19 are about six times that of the 

rate between ages 10 and 14. Crime rates are highest among 

young males and rates of alcohol abuse are high relative to 

other ages. Even though most adolescents come through 

this transitional age well, it’s important to understand the 

risk factors for behavior that can have serious consequences. 

Genes, childhood experience, and the environment in which 

a young person reaches adolescence all shape behavior. 

Adding to this complex picture, research is revealing how all 

these factors act in the context of a brain that is changing, 

with its own impact on behavior. 
The research has turned up some surprises, among them 

the discovery of striking changes taking place during the 

teen years. These findings have altered long-held assumptions about the timing of brain maturation. In key ways, the 

brain doesn’t look like that of an adult until the early 20s. 

One of the ways that 

scientists have searched for the 

causes of mental illness is by studying 

the development of the brain from 

birth to adulthood. Powerful new 

technologies have enabled them to 

track the growth of the brain 

and to investigate the 

connections between brain 

function, development, 

and behavior.

An understanding of how the brain of an adolescent is 

changing may help explain a puzzling contradiction of 

adolescence: young people at this age are close to a lifelong 

peak of physical health, strength, and mental capacity, and 

yet, for some, this can be a hazardous age. Mortality rates 

jump between early and late adolescence. Rates of death by 

injury between ages 15 to 19 are about six times that of the 

rate between ages 10 and 14. Crime rates are highest among 

young males and rates of alcohol abuse are high relative to 

other ages. Even though most adolescents come through 

this transitional age well, it’s important to understand the 

risk factors for behavior that can have serious consequences. 

Genes, childhood experience, and the environment in which 

a young person reaches adolescence all shape behavior. 

Adding to this complex picture, research is revealing how all 

these factors act in the context of a brain that is changing, 

with its own impact on behavior. 
The research has turned up some surprises, among them 

the discovery of striking changes taking place during the 

teen years. These findings have altered long-held assumptions about the timing of brain maturation. In key ways, the 

brain doesn’t look like that of an adult until the early 20s. 

An understanding of how the brain of an adolescent is 

changing may help explain a puzzling contradiction of 

adolescence: young people at this age are close to a lifelong 

peak of physical health, strength, and mental capacity, and 

yet, for some, this can be a hazardous age. Mortality rates 

jump between early and late adolescence. Rates of death by 

injury between ages 15 to 19 are about six times that of the 

rate between ages 10 and 14. Crime rates are highest among 

young males and rates of alcohol abuse are high relative to 

other ages. Even though most adolescents come through 

this transitional age well, it’s important to understand the 

risk factors for behavior that can have serious consequences. 

Genes, childhood experience, and the environment in which 

a young person reaches adolescence all shape behavior. 

Adding to this complex picture, research is revealing how all 

these factors act in the context of a brain that is changing, 

with its own impact on behavior. 

One of the ways that 

scientists have searched for the 

causes of mental illness is by studying 

the development of the brain from 

birth to adulthood. Powerful new 

technologies have enabled them to 

track the growth of the brain 

and to investigate the 

connections between brain 

function, development, 

and behavior.
The research has turned up some surprises, among them 

the discovery of striking changes taking place during the 

teen years. These findings have altered long-held assumptions about the timing of brain maturation. In key ways, the 

brain doesn’t look like that of an adult until the early 20s. 

An understanding of how the brain of an adolescent is 

changing may help explain a puzzling contradiction of 

adolescence: young people at this age are close to a lifelong 

peak of physical health, strength, and mental capacity, and 

yet, for some, this can be a hazardous age. Mortality rates 

jump between early and late adolescence. Rates of death by 

injury between ages 15 to 19 are about six times that of the 

rate between ages 10 and 14. Crime rates are highest among 

young males and rates of alcohol abuse are high relative to 

other ages. Even though most adolescents come through 

this transitional age well, it’s important to understand the 

risk factors for behavior that can have serious consequences. 

Genes, childhood experience, and the environment in which 

a young person reaches adolescence all shape behavior. 

Adding to this complex picture, research is revealing how all 

these factors act in the context of a brain that is changing, 

with its own impact on behavior. 

One of the ways that 

scientists have searched for the 

causes of mental illness is by studying 

the development of the brain from 

birth to adulthood. Powerful new 

technologies have enabled them to 

track the growth of the brain 

and to investigate the 

connections between brain 

function, development, 

and behavior.
The research has turned up some surprises, among them 

the discovery of striking changes taking place during the 

teen years. These findings have altered long-held assumptions about the timing of brain maturation. In key ways, the 

brain doesn’t look like that of an adult until the early 20s. 

An understanding of how the brain of an adolescent is 

changing may help explain a puzzling contradiction of 

adolescence: young people at this age are close to a lifelong 

peak of physical health, strength, and mental capacity, and 

yet, for some, this can be a hazardous age. Mortality rates 

jump between early and late adolescence. Rates of death by 

injury between ages 15 to 19 are about six times that of the 

rate between ages 10 and 14. Crime rates are highest among 

young males and rates of alcohol abuse are high relative to 

other ages. Even though most adolescents come through 

this transitional age well, it’s important to understand the 

risk factors for behavior that can have serious consequences. 

Genes, childhood experience, and the environment in which 

a young person reaches adolescence all shape behavior. 

Adding to this complex picture, research is revealing how all 

these factors act in the context of a brain that is changing, 

with its own impact on behavior. 

One of the ways that 

scientists have searched for the 

causes of mental illness is by studying 

the development of the brain from 

birth to adulthood. Powerful new 

technologies have enabled them to 

track the growth of the brain 

and to investigate the 

connections between brain 

function, development, 

and behavior.
Teens and the Brain: More 

Questions for Research

Scientists continue to investigate the development of the 

brain and the relationship between the changes taking 

place, behavior, and health. The following questions are 

among the important ones that are targets of research: 

How do experience and environment interact with 

genetic preprogramming to shape the maturing brain, 

and as a result, future abilities and behavior? In other 

words, to what extent does what a teen does and learns 

shape his or her brain over the rest of a lifetime?

In what ways do features unique to the teen brain play a 

role in the high rates of illicit substance use and alcohol 

abuse in the late teen to young adult years? Does the 

adolescent capacity for learning make this a stage of 

particular vulnerability to addiction?

Why is it so often the case that, for many mental disorders, symptoms first emerge during adolescence and 

young adulthood? 

This last question has been the central reason to study brain 

development from infancy to adulthood. Scientists increasingly view mental illnesses as developmental disorders 

that have their roots in the processes involved in how the 

brain matures. By studying how the circuitry of the brain 

develops, scientists hope to identify when and for what 

reasons development goes off track. Brain imaging studies 

have revealed distinctive variations in growth patterns of 

brain tissue in youth who show signs of conditions affecting 

mental health. Ongoing research is providing information 

on how genetic factors increase or reduce vulnerability 

to mental illness; and how experiences during infancy, 

childhood, and adolescence can increase the risk of mental 

illness or protect against it. 
Teens and the Brain: More 

Questions for Research

Scientists continue to investigate the development of the 

brain and the relationship between the changes taking 

place, behavior, and health. The following questions are 

among the important ones that are targets of research: 

 How do experience and environment interact with 

genetic preprogramming to shape the maturing brain, 

and as a result, future abilities and behavior? In other 

words, to what extent does what a teen does and learns 

shape his or her brain over the rest of a lifetime?

 In what ways do features unique to the teen brain play a 

role in the high rates of illicit substance use and alcohol 

abuse in the late teen to young adult years? Does the 

adolescent capacity for learning make this a stage of 

particular vulnerability to addiction?

 Why is it so often the case that, for many mental disorders, symptoms first emerge during adolescence and 

young adulthood? 

This last question has been the central reason to study brain 

development from infancy to adulthood. Scientists increasingly view mental illnesses as developmental disorders 

that have their roots in the processes involved in how the 

brain matures. By studying how the circuitry of the brain 

develops, scientists hope to identify when and for what 

reasons development goes off track. Brain imaging studies 

have revealed distinctive variations in growth patterns of 

brain tissue in youth who show signs of conditions affecting 

mental health. Ongoing research is providing information 

on how genetic factors increase or reduce vulnerability 

to mental illness; and how experiences during infancy, 

childhood, and adolescence can increase the risk of mental 

illness or protect against it. 
Teens and the Brain: More 

Questions for Research

Scientists continue to investigate the development of the 

brain and the relationship between the changes taking 

place, behavior, and health. The following questions are 

among the important ones that are targets of research: 

 How do experience and environment interact with 

genetic preprogramming to shape the maturing brain, 

and as a result, future abilities and behavior? In other 

words, to what extent does what a teen does and learns 

shape his or her brain over the rest of a lifetime?

 In what ways do features unique to the teen brain play a 

role in the high rates of illicit substance use and alcohol 

abuse in the late teen to young adult years? Does the 

adolescent capacity for learning make this a stage of 

particular vulnerability to addiction?

 Why is it so often the case that, for many mental disorders, symptoms first emerge during adolescence and 

young adulthood? 

This last question has been the central reason to study brain 

development from infancy to adulthood. Scientists increasingly view mental illnesses as developmental disorders 

that have their roots in the processes involved in how the 

brain matures. By studying how the circuitry of the brain 

develops, scientists hope to identify when and for what 

reasons development goes off track. Brain imaging studies 

have revealed distinctive variations in growth patterns of 

brain tissue in youth who show signs of conditions affecting 

mental health. Ongoing research is providing information 

on how genetic factors increase or reduce vulnerability 

to mental illness; and how experiences during infancy, 

childhood, and adolescence can increase the risk of mental 

illness or protect against it. 
Teens and the Brain: More 

Questions for Research

Scientists continue to investigate the development of the 

brain and the relationship between the changes taking 

place, behavior, and health. The following questions are 

among the important ones that are targets of research: 

 How do experience and environment interact with 

genetic preprogramming to shape the maturing brain, 

and as a result, future abilities and behavior? In other 

words, to what extent does what a teen does and learns 

shape his or her brain over the rest of a lifetime?

 In what ways do features unique to the teen brain play a 

role in the high rates of illicit substance use and alcohol 

abuse in the late teen to young adult years? Does the 

adolescent capacity for learning make this a stage of 

particular vulnerability to addiction?

 Why is it so often the case that, for many mental disorders, symptoms first emerge during adolescence and 

young adulthood? 

This last question has been the central reason to study brain 

development from infancy to adulthood. Scientists increasingly view mental illnesses as developmental disorders 

that have their roots in the processes involved in how the 

brain matures. By studying how the circuitry of the brain 

develops, scientists hope to identify when and for what 

reasons development goes off track. Brain imaging studies 

have revealed distinctive variations in growth patterns of 

brain tissue in youth who show signs of conditions affecting 

mental health. Ongoing research is providing information 

on how genetic factors increase or reduce vulnerability 

to mental illness; and how experiences during infancy, 

childhood, and adolescence can increase the risk of mental 

illness or protect against it. 

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