Sunday, August 3, 2014

"Thinking outside the car": Understanding the teen brain

The most common way of explaining how the teen brain works is that the "emotional" subsystem in the brain is well-developed during adolescence, while the inhibtory control and rational thinking part of the brain is under-developed. Further, the connections between these two systems, emotional and emotion-inhibiting, are not completely established. This theory of adolescent brain development is often described as "all gas and no brakes." Now, if any of you have teenaged children, grandchildren, nieces, nephews, or even remember being a teenager, this analogy likely rings trues.

In May, I attended a research presentation of Dr. Jennifer Pfeifer, a psychologist at the University of Oregon. She and her colleagues are trying to challenge this simplified understanding of teens. She argues in a review published in 2012 that the existing and dominant model for understanding teen behavior as a function of mismatched development of the emotional and emotion-controlling systems in the brain is much too simplified to be accurate. In addition, she describes a number of bodies of evidence that appear to contradict this theory, such as that of the developmental model for the development of depression and a number of studies showing less activity in the emotional subsystems in the brain. Furthermore, she offers the astute observation that few of the existing studies relate results from within an fMRI to behavior in the 'real world' where most of us live.

Instead, Pfeifer hypothesized that the systems in the brain responsible for processing social information were also involved in helping people, specifically teens, regulate emotional behavior in the world. Adolescence is nothing if not social. Teenagers spend more time with their peers than any other group, and it's not surprising to anyone to learn that social influence is highly predictive of teen behavior. However, according to the traditional model of adolescent brain development, there is no space for how the brain processes social information.

Pfeifer and her colleagues were interested in this gap in our theoretical understanding of teen behavior and development. So she and her colleagues conducted a study to answer the question:

Does social reward explain the association between emotional reactivity and risk-taking behaviors among teens? 

To answer this question, they recruited 38 typically developing youth. These youth participated in an fMRI (brain scan) at ages 10 and 13. During these scans, youth passively observed images of faces displaying a range of emotions. The youth also completed surveys of their risk-taking behaviors and their ability to resist peer influence. They then compared activity during the scans in the ventral striatum (associated with processing reward), amygdala (processing emotion), and vmPFC (associated with inhibiting emotional responses).

First they found that activity in the ventral striatum and vmPFC increased in response to the faces between ages 10 and 13, suggesting possibly that the brain becomes more responsive to rewards as well as attempts to recruit more inhibitory resources after the transition to adolescence. In contrast, there was no increase in amygdala activity, as one might expect given the "all gas no brakes" theory.

They also found increases in ventral striatum activity were related to greater resistance to peer influence and slight decreases in risk-taking behavior from age 10 to age 13. In fact, the relationship between reward-processing activity and resistance to peer influence was only significant at age 13. This is evidence that during the transition to adolescence, processing of rewards related to social information such as emotions may be protective for kids learning how to resist negative peer influences.  

In summary, teen behavior is undeniably influenced by their peers which can be a good or a bad thing. So while teens may be more gas than brakes, we have to "think outside the car" as Dr. Pfeifer aptly stated in her presentation. Teenagers can drive far more skillfully in good weather with little traffic, just as they can make wise decisions about how to behave and spend their time in a rewarding environment. It's when the social environment is not rewarding that emotional systems can begin to overwhelm the regulatory systems and result in risk-taking and negative attention seeking behavior, such as risky sexual activity, early substance abuse, reduced participation in school, and rule-breaking.

What we can do, based in part on the findings of this line of research, is capitalize on making the "good" social influences as rewarding as possible. Praise their attempts to say "Thank you so much Grandma" when they get that ugly duck sweater for their birthday instead of making an ick face; give them ice cream during social activities that you want them to continue. Be creative, be tireless. Also, knowledge is power.

The internet can be a scary place to send a young and impressionable mind. That's why I was thrilled when I learned about a new website called ShimmerTeen. ShimmerTeen holds a wealth of positive supportive information for teen girls about health, relationships, school, and the media to counteract all those completely un-helpful sources of information that teen girls are exposed to all day, everyday. We really need more organizations promoting healthy messages for young girls, because the truth is that teens are more vulnerable to social context than any other age group, so let's set them up for success by surrounding them with fun and helpful answers to the questions and concerns they have.

Pfeifer, J. H., & Allen, N. B. (2012). Arrested development? Reconsidering dual-systems models of brain function in adolescence and disorders. Trends in cognitive sciences, 16(6), 322-329.

Pfeifer, J. H., Masten, C. L., Moore III, W. E., Oswald, T. M., Mazziotta, J. C., Iacoboni, M., & Dapretto, M. (2011). Entering adolescence: resistance to peer influence, risky behavior, and neural changes in emotion reactivity. Neuron,69(5), 1029-1036.

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