A Look Inside the Teenage Brain
Do you ever question why your teen is sometimes able to make rational, healthy choices that make you feel incredibly proud, yet other times they’re quick to jump to conclusions, don’t think things through, or dysregulate emotionally, leaving you baffled? Teenage brain development plays a significant role in why you’re seeing this.
By age six, children’s brains are about 90 to 95 percent of their adult size, yet during adolescence, the brain is being “remodeled” so it can function as an adult brain. Brain remodeling continues until about age twenty-five. The biggest change aligns with a concept of “use it or lose it,” in which the brain becomes more efficient by strengthening connections.
Essentially, the brain gets rid of connections that are no longer needed, while reinforcing connections that are needed. This process, called pruning, begins in the back of the brain and ends with the prefrontal cortex, part of the frontal cortex and located in the front of the brain. The prefrontal cortex is the thinking part of the brain that controls reasoning. We will talk more about the frontal cortex and its role in the next section; however, it’s important to note that the frontal cortex is not fully developed until early adulthood.
Because their prefrontal cortex is still developing, teens rely on the amygdala to process information. The amygdala is the part of the brain that initiates the “fight or flight” response and manages immediate reactions, including fear. The amygdala plays a role in emotions, aggression, and impulses. This is why we see teens sometimes acting with emotions versus rational decision-making.
When you ask, “What were you thinking?” the answer might be, “I wasn’t thinking.” And, in part, this is true. This isn’t to suggest that teens will always act emotionally or that they shouldn’t be held accountable for their actions. It’s to alert caregivers that the emotional part of the brain and the rational part of the brain aren’t yet working like a well-balanced machine. We can expect teens at times to act impulsively, engage in risky behaviors, succumb to peer pressure, misunderstand social and emotional cues, and be less likely to pause and think about the consequences of a choice before they act or change inappropriate behaviors.
Another part of the brain, the limbic system, is responsible for primal instincts including pleasure. More clearly, the limbic system is the reward center. Findings show that there’s a mismatch between this system, which matures between ages ten and twelve, and the prefrontal cortex, which isn’t fully developed until age twenty-five. This explains why teens are likely to engage in reward-seeking behaviors. The pleasure and reward system are firing away, while the prefrontal cortex, which is responsible for self-control, isn’t always equipped to remind teens to disengage from risky behaviors.
RULE OF THUMB: THEIR FRONTAL LOBE IS (ALMOST) ALWAYS THE CULPRIT
The frontal cortex is responsible for short-term memory storage, speech coordination, and thinking. The prefrontal cortex, which is part of the frontal cortex, regulates emotion and cognitive control. Cognitive control focuses on self-awareness and supports decision-making because it allows the mind to overrule impulses. With cognitive control, decisions are based on goals, not habits or reactions. This part of the brain is not fully developed until age twenty-five, yet the limbic system (the risk and reward system) and the amygdala (the emotional processing center) are operating at essentially full capacity in teens.
Let’s tie this all together using an example of a risky behavior. Say your daughter is hanging out with her friends and they tell her to smoke a cigarette (risky behavior). She knows that smoking cigarettes isn’t good for you and knows that you will be upset if she smokes. She decides to smoke anyway. Gaining the acceptance of her peers activates the limbic system. The reward of belonging wins against the less-than-average decision-making capacities of the prefrontal cortex. The prefrontal cortex doesn’t stand a chance against the limbic system because it’s still developing.
The still-maturing frontal cortex can’t always send the message, “Hey, this isn’t a good idea. Think about the consequences of your choices.” This is especially true when teens are with peers. Teens are highly perceptive regarding what it means to belong, and the need to be accepted becomes an automatic message that replays over and over, further reinforcing the brain’s reward system.
Risk-taking looks different for every teen, and can include experimenting with alcohol, drugs, and sexual behaviors; driving too fast; or skipping school. The takeaway here is that the developing frontal cortex plays a significant role in why teens make poor choices or engage in risk-taking.
