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Understanding the Teen Mind: Beware, Pruning Ahead

March 11, 2014

By Leslie Durr, PhD, RN, PMHCNS-BC
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The opinions expressed by Psychiatry & Behavioral Health Learning Network bloggers and those providing comments are theirs alone and are not meant to reflect the opinions of the publication.

Any therapist who works with adolescents will tell you about the challenges of working with that age group. 

Years ago, adolescence was thought to be an artificial construct in contemporary society. An examination of the historical origins of adolescence as a unique social group suggests that adolescence did not occur until somewhere in the 1800s. Before that, individuals moved from childhood to adulthood with the attendant rights and responsibilities. 

And yet, it’s apparent something is different about people in their teens. They may have the bodies of adults, and their reasoning skills may, at times, seem mature, but how to explain the impulsivity, often poor judgment, and wide-ranging emotional swings? 

More recently it has been proposed that teens respond differently to the world because of hormones, or attitude, or because they simply need independence. 

With the advent of sophisticated imaging techniques, we now know that when adolescents are studied through magnetic resonance imaging (MRI), we can see that their brains actually work differently from adult brains. The differences are explained by what is called “neural pruning” or “synaptic pruning”.  Either way, the word “pruning” is the operative term. 

Over the first few years of life, there is a great proliferation of connections between brain cells that contributes to what is called “neural plasticity”.  For example, if a child receives a brain injury before age 10, another area of the brain can often take over the functions of the damaged region, a flexibility that decreases with age. 

During the adolescent years, however, there is a pruning back of these connections. Scientists speculate that the brain decides which neural links to keep, based on how frequently they are used. Connections that are rarely called upon are deemed superfluous and eliminated. 

One study found that the teenage medial prefrontal cortex, the part of the brain associated with executive function, empathy, and guilt, is underused compared to that of adults. But as adolescents mature, they begin to use this region more when making decisions, indicating that they increasingly think like adults. 

Besides decision making, the prefrontal cortex is involved in planning, inhibiting inappropriate social behavior, and social interactions, especially perspective taking and empathy. 

The new research may provide an explanation for why adolescents often fail to heed adults' warnings about such choices as drugs or sex: they may simply not be able to understand and accept arguments that seem logical and decisive to adults. It is also possible that teens misperceive or misunderstand the emotions of adults, leading to miscommunication both in terms of what the teen thinks the adult is feeling and in terms of the teen’s response. 

So, therapy with teens must be two-pronged—the first prong is helping the teen understand that he may be making poor decisions that aren’t getting him the freedom he wants. At one hospital where I worked, whenever teens started to argue that their behavior wasn’t bad, we told the teens that their behavior wasn’t wrong, their behavior was stupid, because it surely wasn’t getting them the freedom and respect they said they wanted. That message usually woke them up and led them to consider their actions a bit more. 

The second prong is providing information to parents that their child is at a point where they are incapable of the kind of reasoned thought that their adult bodies would suggest, and that with time, it will get better. Also, it’s important to help parents stay the course, not throw in the towel, and continue to dispassionately set limits. 

Or as I used to say to my oldest child: I am the wall. Show that you are responsible and the wall moves back a little; show that you are not responsible and the wall moves back in close. Don’t like the wall so close? The power to change that is in your hands. 

That was many years ago. I surely wish we’d known about neural pruning back then.

How you do work with adolescents? 


1. Choudhury S, Blakemore SJ, Charman T. Social cognitive development during adolescence. Social Cognitive and Affective Neuroscience. 2006 December; 1(3): 165–174.

Leslie Durr, PhD, RN, PMHCNS-BC is an advanced practice psychiatric-mental health nurse with a private psychotherapy practice in Charlottesville, Virginia.

The views expressed on this blog are solely those of the blog post author and do not necessarily reflect the views of Psych Congress Network or other Psych Congress Network authors. 

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