We now know that the brain is the last organ to fully develop. While some special birthdays bring important milestones in the journey to adulthood—such as earning the right to drive, vote, and drink alcohol—in truth, brains simply don’t catch up until later. The frontal lobe—the part of the brain that forms judgement, impulse control, empathy, and decision making—isn’t developed yet, explains Frances Jensen, MD, chair of Neurology in the Perelman School of Medicine at the University of Pennsylvania and author of the book “The Teen Brain.” It can take until the mid- to late-20’s for the brain to fully mature. This helps explain why teens are moody, explosive, and more susceptible to addiction to everything from drugs, alcohol, and nicotine, to cell phones.
The driver for brain development is in how the regions of the brain are connected to each other. The connection tracks need to be insulated with a fat called myelin for fast signaling. The process moves from the back of the brain to the frontal lobe, where executive function takes place. This process takes about 20 years. In the teen brain, the frontal lobe can’t be accessed in a rapid manner because the insulation isn’t there yet.
“This is a reason why teens tend to have increased risky behavior,” Jensen said. “They aren’t as readily able to access their frontal lobe in situations to say, ‘That’s a bad idea, I better not do this.’”
Frances Jensen, MD
While the teen brain has some limitations, it also has some advantages over the older, adult brain. As the brain develops, there is enhanced synaptic plasticity—teens learn faster and memories last longer. Each region of the brain is more active in childhood and adolescence than it will be later in life. They are faster learners because they build synapses (connections in the brain) faster. This strength is a superpower in adolescence. It’s one reason why teens seem to easily learn two to three languages, while many adults struggle to learn a new language.
But this learning ability is a double-edged sword. Teens are more prone to addiction because it’s a form of learning. Just as it’s easier for a younger brain to pick up new languages, athletic techniques, or musical instruments, it’s easier for them to pick up addictions, because it’s all just learning. The teenage brain is still figuring out the parameters for “normal” and so it is quicker to adapt to any repeated stimuli.
Substances stimulate the brain in the same way learning stimulates it, but addiction takes place in the limbic system—the reward seeking part of the brain. Because of this, addiction is more efficient in the adolescent brain and teens can get addicted to substances like nicotine or opioids quicker than adults.
“It’s important for adolescents to know that they can get addicted faster,” said Jensen. “While kids aren’t likely to do exactly what parents tell them, it helps for parents to address this and to have a few facts like this to reference to seem more credible.”
One fundamental issue at the core of all these problems is that frontal lobe and its stage of development in adolescents. As adults, we have a filter that prevents our impulses and fleeting desires from becoming actions. Adults are more likely to make better decisions or weigh the implications of certain actions, where a teen doesn’t have the capacity to do so because the frontal lobe is connected last.
“Adults take a moment to think over their decisions before making them, and we chalk that up to our wisdom and experience,” Jensen said. “But the truth is, we give ourselves a little too much credit. All this means is that our frontal lobes are developed enough to regulate our impulses. But teens don’t have this luxury. Their brains aren’t wired to assess situations and make the smartest choices. They are wired to explore, challenge, and push boundaries.”
Jensen’s advice is for parents to step in occasionally to make the calls that teens might not be able to understand just yet. As the teenage brain is a learning machine, discussing ahead of time how they may want to handle a difficult situation can be a learning moment stored for later use. She calls these “frontal lobe assists.” Unlike our impulsive and addiction-prone kids, adults know the consequences and parents need to help them learn the best path forward.