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Did you read this  month’s issue of the Canadian Macleans magazine?  The front cover has a dramatic and frightening headline about brain development:

 “The Shrinking Teenage Brain: New research says our teens’ brains are more vulnerable than we thought.  Poor decisions and bad parenting are doing lasting damage.”

What Happens to Brain Development in a Teenage Brain?

At one point is was thought that the early childhood years (0-3 yrs. and then it became 0-6 yrs.) were the most critical for brain development.  However, new brain research from the last 10-15 years, has now proven that our brains continue to develop, and the teenage years contain another critical period of brain development.  To understand the changes that take place in the brain, they can be divided into grey matter and white matter.

The brain cells known as neurons, or the “building blocks”, form the grey matter.  The connections between the grey matter are called axons or white matter.  The white matter helps to pass the information along from one area of the brain to the next.  Although the grey matter has almost completely stopped growing by age six, the white matter continues to create wiring between the neurons (brain cells) well into one’s twenties.

The last area of the brain to connect with the white matter, is the prefrontal cortex (which I often refer to as the “wise leader” part of our brain).  The prefrontal cortex controls self-regulation, decision making, self awareness, empathy, organization and many more important functions.

In addition to all of this new wiring taking place during adolescence, myelination is also occurring, which means that the white matter axons are being covered in Myelin.  Myelin is a protective fatty material, which allows signals to move faster, and therefore increase the speed of the information being passed on within the brain.  (Myelination continues into one’s thirties.)

Why Are Teenage Brains More Impulsive, Emotional and Risk-Taking?

1) Teenagers have a more difficult time accessing their prefrontal cortex (wise leader part of the brain) because the wiring is not yet fully in place and the myelination process is just in progress.  Therefore, it is more challenging for them to make wise choices and put the “brakes” on their impulses.

2) Simultaneously, puberty triggers the release of hormones that act on the limbic system – the emotional centre of the brain.  Therefore, teenagers experience heightened emotions, alongside a not yet fully developed prefrontal cortex.

3) A hormone called THP, which is released by our bodies when we experience stress, provides calm to children and adults but may have the opposite effect on adolescents.  It may be one of the reasons why more teenagers are prone to anxiety.

4) Teenage brains are highly sensitive to Dopamine, a neurotransmitter, which plays a major role in the area of reward and pleasure.  Even though a teenager may have good reasoning skills, he/she may choose to engage in high-risk behaviours because the pleasure one receives is more motivating than avoiding the risk.

Why Can IQ Change Dramatically in Adolescence?

At one point in time, it was thought that IQ was determined for life, after childhood.  Brain scientists have now discovered that a teenager’s brain undergoes “pruning”, whereby some of the grey matter brain cells that have been built up during childhood, are now “shed”, which makes more room for the growing white matter.

“Use it or lose it” – the teenagers years are a critical time for continuing to use the brain cells that have been built up throughout childhood, as this is when new connections between the neurons are being made.  Likewise, those that are unused will be pruned away.  In one study at the University College London, England, they found that increases in verbal IQ were strongly linked to reading abilities in early adolescence.  They therefore recommended that children with dyslexia, be given lots of audiobooks,  in order that their verbal IQs don’t decrease.

Because of this rapid brain development in the teenage years, teenagers are more sensitive to learning new skills – this is positive for learning new healthy skills but negative for being vulnerable to learning addictive behaviours.

Next week, I’ll write about the consequences on teenage brain development when a youth is engaging in smoking, drinking, drugs and has chronic stress plus the pros and cons of different parenting styles.

I wonder if the current brain research will influence today’s youth to be proactive about growing healthier brains?  Daniel Siegel, an internationally recognized child psychiatrist, has written an excellent book called, Brainstorm: The Power and Purpose of the Teenage Brain.  His hope is for this book to be read, not only by parents, but also by adolescents in order that they can be informed and hopefully motivated to take good care of their brains.

Have a wonderful week,

Warmly,