BJ Casey, PhD
Departments of Psychiatry and Neuroscience
Sackler Institute for Developmental Psychobiology
Weill Medical College of Cornell University
(February 11, 2015)
Self-Control and the Teen Brain: Arrested Development or Adaptive Evolution
How often do we hear about a teenager making a very bad choice? How often do we hear about teenagers experimenting with drugs, binge-drinking alcohol, or starting fights and acting out? How often are these teenagers labeled as deviant, or lacking in some essential brain function causing them to act abnormally? As Dr. Casey explains, bad choices and a lack of self-control are perfectly normal aspects of teenage behavior. Dr. Casey’s research has shown that the adolescent brain is still wiring and fine-tuning connections, building the neural networks responsible for emotion and self-control. The experiences of the teenage years, including experimentation and the test of boundaries, can lead to the healthy development and brain functioning of the adult.
Over the past decade, the teen brain has received significant attention from the media, due in part to the many seeming contradictions in teen behavior and in part to developments in brain imaging that provide the opportunity to look under the hood of the teen brain (Casey, 2013). This developmental period is one when an individual is probably stronger, of higher reasoning capacity, and more resistant to disease than ever before, yet mortality rates increase by 200 percent. These untimely deaths are not due to disease but to preventable deaths associated with adolescents putting themselves in harm’s way (e.g., accidental fatalities, suicide) with sensation seeking at an all-time high (Steinberg et al. 2008) and anxiety and mood disorders peaking (Kessler et al. 2005, Merikangas et al. 2010).
So what brain changes take place during adolescence that may explain these seeming inconsistencies in behavior? Too often in describing the adolescent brain, we suggest it has no brakes or steering wheel (Bell &McBride 2010), as if it is defective in some way. However, we don’t characterize other formative years of development as defective (Steinberg 2012). When a newborn is unable to talk or walk we do not refer to this inability as a deficit but rather as normal development. Yet the adolescent who makes a bad choice in the heat of the moment among peers is described as having no frontal lobe or as being deviant in some way. Rather than depicting the teen brain and teen behavior as defective, we portray a brain that
is sculpted by evolutionarily based biological constraints and experiences as it adapts to the unique intellectual, physical, sexual, and social challenges of adolescence and successfully transitions from relative dependence to independence from the parent.
We present evidence that these alarming health statistics are in part due to diminished self-control —
the ability to inhibit inappropriate desires, emotions, and actions in favor of appropriate ones (Casey, 2015). Changes in self-control during adolescence parallel a series of developmental cascades in the wiring and fine-tuning of connections within complex subcortical and cortical prefrontal and limbic circuitries. These adolescent-specific changes reflect both evolutionarily based biological constraints and unique experiences of this period. Having sufficient time and space to freely explore and experiment may enhance the formation of the adolescent’s self-identity (Erikson 1968) and lead to healthy development into a socially functioning adult.