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Maturation of the Teen Brain

Implications for parents, mentors, and society

How do we decide when a young person has developed adult judgment?  Auto rental companies do not rent to drivers under age 25. The risk of damage and destruction of property is too great for the companies to expose the vehicles to younger immature drivers. So, what is maturity and how and when does it happen? Maturity is completeness of growth and development. There are three components to this process: physical, mental, and what might be called cognitive. Each of these has its own separate timetable of completion.  Physical and mental maturity is fairly obvious to an outside observer, and can be measured—physical by weight and height, and mental, by memory and technical or artistic work.  Both of these are usually complete by the end of the teen years.

Cognitive maturity is less well-understood and, until recently, its time of completion has been undetermined. As you will see, though, in this paper, understanding of adolescent cognitive development has huge implications for all of society, and recent breakthroughs in neuroscience will forever change our understanding of adolescents and the role adults play in their lives. It is important to differentiate the terms "adolescent" and "teenager" from each other. The adolescent years are the period of time during which a person grows from puberty to cognitive maturity. This period extends well past the teen years.  In fact, most college students are still adolescents. The purpose of this paper is to discuss the data proving that—of physical, mental, and cognitive maturity—it is cognitive maturity that develops last, usually not reaching completion until the mid-twenties.

Physically most people become mature as teenagers, some startlingly so. LeBron James, of the Cleveland Cavaliers basketball team, straight out of high school, can run circles around some highly experienced NBA players.

Mentally, teenagers achieve great maturity of intelligence—their ability to calculate, memorize, and create is sometimes startling. The movie "Amadeus," about Mozart, graphically illustrated this. Despite his youthful mental prowess, because his cognitive maturity lagged behind, Mozart's capacity for making decisions that required judgment was strikingly immature. The primary message of recent groundbreaking neuroscience is that cognitive maturity develops last, after physical and mental maturity, for all adolescents. This research shows that cognitive maturity occurs in the mid-twenties, and includes the following:

  • Mature judgment
  • Seeing into the future
  • Seeing how behavior can affect future
  • Associating cause and effect
  • Moral intelligence
  • Abstract thinking
  • Seeing what is not obvious
  • Planning and decision-making
  • Rational behavior and decision-making
  • Rules of social conduct
  • Understanding rules of social conduct

Most individuals have never thought about when these abilities develop or where they originate. Ancient writings often say they come from the heart—clearly separating them from just the ability to think. Perhaps, in concept, they were not far off. Neuroscientists, led by Jay Giedd, MD, Chief of Brain Imaging at the National Institute of Mental Health, are showing us that these capacities primarily reside within the pre-frontal cortex of the frontal lobes of the brain. MRI (magnetic resonance imaging) is a technology that uses strong magnets to take pictures of body parts. New MRI studies of the developing brains of normal adolescents clearly show that the physical development of the pre-frontal cortex is not complete until the mid-twenties.

Before recent research revealed this startling new information, adolescent specialists had assumed that adolescents acted the way they do because of raging "hormones," heredity, bad or good environmental factors, or a host of other reasons, all hopelessly commingled into a stew of influences that could probably never be understood. It is not that these other factors don't influence adolescents; they do. The issue is that underlying all of this—the overriding influence—is an incompletely developed pre-frontal cortex that limits the ability of adolescents to independently make mature decisions.

Adolescents' ability to make totally mature judgment calls based on abstract thinking, i.e., seeing how current behavior affects future outcomes, is limited. Therefore, their failures in this area are not necessarily moral. Quite literally, they do not have the brain cell connections to "do" judgment calculations. This means that, if parents, mentors, and the rest of society fails to give adolescents guidance (and, if necessary, discipline), if we fail to help them make the best decisions for themselves and for society, we abandon them to guidance by their own brains—brains which are incompletely developed and that are incapable of the truly mature judgment.

Surprisingly, incomplete cognitive development of the brain lasts well through college years and, therefore, has enormous implications for the responsibility of parents and university administrators to that group. We fail young persons when we give them "just the facts" and say "you decide" without guiding them to and supporting them in making the best decisions. We fail them when we expect them to control their impulses and avoid risk behaviors, when we abandon them at critical decision-points to their own minds—minds with a limited capacity for abstract thinking.

In considering how his research has shaped the way he parents his own children, Dr. Jay Giedd says it has made him comfortable with the fact that giving guidance to his children, even through their college years, is not "butting in." He points out that trial and error and mistakes and successes are all a part of the process of brain molding that is supposed to happen. Parents need to understand this and take it into consideration as their adolescents mature, intervening to help prevent "irreversible" mistakes whenever possible. Parents and mentors and all of society have a responsibility to adolescents. This new information allows adults to comfortably help our children develop wisdom, avoid dangerous risk behaviors, and have the brightest futures.


*This article was modified from "Maturation of the teen brain: Implications for parents, mentors and society", an article in the Medical Institute's Integrated Sexual Health Today publication. For more information, contact The Medical Institute at Used by permission.