The Way They’re Wired: Your Teen’s Brain, Explained

The teenage years can be especially trying because they take risks, they show poor judgment and exhibit lousy decision-making skills. But it may actually not be their fault. Understanding the teen brain and its development is imperative for parents so they can get through the teen years with their own mind in tact. Here’s what you need to know.

ONE DAY, I strolled into the kitchen to find my 14-year-old daughter cutting a piece of cheese on the counter top with a sharp knife. I think I could feel the sharp blade scoring my pristine counter top as if she was cutting my own skin. WHAAAA!?? I take great pride in how adept my kids are in the kitchen. From a young age, they were trained to use the gas stove and microwave with great care. They were becoming quite the cooks and bakers. So what the heck was she thinking scratching up my counters like that?

Oh right; thinking. Hmmmm I forgot—she’s 14 now. As a family therapist who understands the developmental changes in adolescence, I was reminded that we were entering a new phase. This was not disrespect or laziness. This was simply a case of poor judgment and decision-making because her brain had begun a distinct phase called neuronal pruning, but to lay people it’s best just to imagine her cranium had a big piece of yellow hazard tape wrapped around it saying “under construction.”

You see, we have fairly new information about brain development. Up until the invention of MRI (magnetic resonance imaging) machines, we didn’t have a full picture of the events that take place in the brain as it grows, develops and ages. We had long understood that the brain does the vast majority of its growth in early childhood. Just to throw some impressive numbers around: from birth to age three, a child is making 700 new neural connections a second! That first spurt is followed by a steady decline, however, we now know that there is a surprising second wave of brain development.

From birth to age 3, a child is making 700 new neural connections a second!


Just prior to puberty, the brain enters a new growth phase, where it lays down the grey matter or the “working tissue” of the brain. I like to think of this as the “MacGyver Brain”—a real firecracker, ready to connect ideas and solve problems. It’s a bit like feast before the famine. This second and final stage of brain development begins around age 16 or 17, and isn’t complete until well into early adulthood, peaking at around age 25. This phase of development includes neuronal pruning with the brain taking shape, like the trimming of a bonsai plant. The brain starts out with a connection or road to every town on the map. It matures by pruning these connections because you can move information a lot faster if you build a super highway around the connections that are well used, and diminish the links to the shanty towns that don’t see much traffic. The brain takes a “use it or lose it” approach to this reconfiguration. For example, if you don’t play the violin, your brain doesn’t need a connection to the part that controls the related neural pathways.

The areas of the brain that develop last are those responsible for the most complex activities: the so called “executive functions” that are the centre for reasoning, working memory, inhibition, impulse control and apparently the elusive judgment to use a cutting board for cutting cheese on a countertop.

Until the executive functions mature, it is as if the teen brain lacks a full set of brakes. It is all go, go, go!”


Until the executive functions mature, it is as if the teen brain lacks a full set of brakes. It is all go, go, go! In this way, teens are primed for risk-taking. They may judge risk accurately, but the lack of brakes causes them to take risks anyways. This makes evolutionary sense. Think of the little baby bird being coaxed by its parents to take its first flight. You have to be a bit nutsy to jump from the edge of the nest and try flying for the first time, don’t you think? It takes guts to go to college, live in residence, start a job and all the other challenges of independence and emancipation from parents. Overriding fear with raw courage has a biological root. But it can also lead to unwanted consequences if we don’t manage the process well.

Your child will want to seek excitement. They want to be adult-like, but they don’t yet have the maturity. Interestingly, youth report that it is largely boredom that drives them to drink and behave foolishly. So, as parents, we have a challenge: helping to navigate our kids through the teen years involves steering them toward appropriate thrill-seeking activities. What does that look like? It depends on your teen. If they love music, it could be playing guitar or singing at an open mic café. If they are athletic, it could be engaging in a sport like hang gliding. Travelling and taking courses abroad in another country might also be excitingly scary.

Most importantly, we need to ensure our kids don’t lazily channel their thrill-seeking tendencies into drinking. For a full discussion on preventing underage drinking and how to talk to teens, see my Family Talk series on youtube.com/user/AlysonSchaferVideos.You might try watching them with your teens to help open the door to conversations about alcohol.

Scored counter tops aren’t good but times like these are good reminders that our kids are growing up and we can help them with informed parenting.

BY alyson schafer


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