Teen Brains — Fit for Purpose

Mrs Anne Ingram, Dean of Students

The teenage brain is a wondrous organ, capable of immense stimulation and stunning feats of learning. Granville Stanley Hall, the founder of the child study movement, wrote in 1904 about the exuberance of adolescence:

The years are the best decade of life. No age is so responsive to all the best and wisest adult endeavour. In no psychic soil, too, does seed, bad as well as good, strike such deep root, grow so rankly or bear fruit so quickly or so surely (Hall, as cited in Jensen, 2015).

Hall described adolescence in a truly optimistic fashion as ‘the birthday of the imagination’ and to this day this still rings true, and fiercely so. But Hall also asserted that adolescence is inherently a time of ‘storm and stress’ when all young people go through an emotional and behavioural upheaval before establishing a more stable equilibrium in adulthood. This age of exhilaration also encompasses a range of dangers including impulsivity, risk-taking, mood swings, lack of insight and poor judgement.

Parents the world over have struggled with and pondered the class of humans we call teenagers and this exciting but seemingly treacherous period of development. To navigate such a turbulent time is difficult for any family, when daughters become unfamiliar, unpredictable and bent on being different. It can be confusing, exhilarating, frustrating and maddening, all at the same time. We can take some comfort from history and know that we are not alone! Aristotle concluded more than 2 300 years ago that ‘the young are heated by Nature as drunken men by wine’. A shepherd in William Shakespeare’s The Winter’s Tale laments this period of youth, wishing that ‘there were no age between ten and three-and-twenty’ (Dobbs, 2011). Hall’s ‘storm and stress’ links in with Freud’s view of adolescence as an expression of torturous psychosexual conflict. Current child psychologist Michael Carr-Gregg refers to the ‘princess bitchface’ syndrome. Adolescence, through the ages, it would seem, has always been a problem.

Until quite recently, the neuroscience of the adolescent brain was underfunded, under-researched and certainly not well understood. Scientists believed that brain growth was complete by the kindergarten years. This incorrect assumption promoted a number of myths and misconceptions about the teenage brain and adolescent behaviour that are now so ingrained that they have become accepted social beliefs: teens are impulsive and emotional because of surging hormones; teens are rebellious and oppositional because they want to be difficult and different; the die is cast at puberty as far as IQ or apparent talents are concerned (Jensen, 2015).

With the development of brain-imaging technologies, it has been possible to view the teen brain in sufficient detail to study both its physical development and patterns of activity with very surprising results. How mistaken we were to view it through the prism of adult neurobiology. When it comes to functioning, wiring and capacity, all are different in the adolescent brain (Jensen, 2015).

Between the twelfth and twenty-fifth years, the frontal lobes of the brain experience an extensive reorganisation that can be likened to a network and wiring upgrade. The axons — the long fibres that nerve cells use to send signals to other neurons — gradually become more insulated with a fatty substance called myelin which serves to boost the axons’ transmission speed up to one hundred times. Simultaneously, dendrites, the branchlike connections between neurons, grow ‘twiggier’ and the most heavily used synapses — the chemical junctures across which axons and dendrites communicate — grow richer and stronger. At the same time, the synapses that see little use begin to wither. This synaptic pruning causes the brain’s cortex — the area of our brain where we do much of our conscious and complicated thinking — to become more efficient. Because the brain is winnowing, ridding itself of unused neural circuitry, it is highly malleable and in a state of experience-dependent re-organisation.

As these brain changes are slowly taking shape, teenagers tend to rely on a part of their brain called the amygdala during decision-making, because their frontal lobes are less reliable. The amygdala (part of the brain’s limbic system) is responsible for impulsive and aggressive behaviour and its dominance makes adolescents more prone to react with gut instincts. A fully-developed frontal cortex offers a check of emotions and impulses originating from the amygdala but this is not the case for teenagers. This slow and uneven development of the brain offers an alluringly pithy explanation of teenage behaviour.

Recent research has begun to view current brain findings in a brighter, more flattering light, one distinctly coloured by evolutionary theory. The adaptive-adolescent story casts the teen less as a rough draft than as an exquisitely sensitive, highly adaptable creature, wired almost perfectly for the job of moving from the safety of home into the complicated world outside. This sits well with biology’s most fundamental principle, that of natural selection. Selection does not tolerate dysfunctional traits. If adolescence is a collection of these — angst, idiocy, haste, impulsiveness, selfishness and reckless bumbling — then how did these traits survive selection (Dobbs, 2011)?

B.J. Casey, neuroscientist at Weill Cornell Medical College, Qatar, has spent substantial time applying brain and genetic studies to understanding adolescence, and sees past the distracting, dopey, monosyllabic teenager to view the adaptive adolescent within.

We’re so used to seeing adolescence as a problem. But the more we learn about what really makes this period unique, the more adolescence starts to seem like a highly functional, even adaptive period. It’s exactly what you‘d need to do the things you have to do then (Casey, as cited in Dobbs, 2011).

Teenagers are highly social creatures who gravitate towards their peers and crave excitement, novelty and risk. While this gives parents cause for concern (and we often find ourselves stumbling as we walk the blurry line between helping and hindering our children as they move towards adulthood), it is critical to look beyond these behaviours and with a view to the adaptive edge that this period of development affords youth. Teenagers meet more people and create wider circles of friends. Their risk-taking often requires moving out of the home, into less secure situations. Resilience and self-confidence grow. They gravitate towards their peers and away from their parents for a most powerful reason — to invest in the future rather than the past. While they may have entered a world made by their parents, they will live most of their lives in a world run by their peers, and building relationships with them will bear critically on success.

Teenagers can be moody, impulsive, and exasperating but wonderful, interesting and full of promise. They are energetic, caring and capable of making many contributions to their communities. Science attests that the teen brain is at a very special point in development which offers unique vulnerabilities but also the ability to harness exceptional strengths. In times of doubt, when our teens are at their most maddening, take inspiration in the prolonged plasticity of those late-developing frontal areas as they slowly mature. This delayed completion heightens flexibility just as our teenagers confront and enter the world they will face as adults, fit for purpose.


Dobbs, D. (October 2011). Beautiful brains. National Geographic Magazine. Retrieved from http://ngm.nationalgeographic.com/print/2011/10/teenage-brains/dobbs-text

Jensen, F. (2015). The teenage brain — A neuroscientist’s survival guide to raising adolescents and young adults. HarperCollins: London.