Parents with teenagers ask themselves questions like this every day. And while the “alien theory” may seem briefly plausible on the subjective level, researchers in recent years have begun to unlock the mysteries of the adolescent brain, and have started to provide answers to explain why teenagers act the way they do.
In short, the teenage brain is undergoing rewiring. Neuroscience had long held that thebrain was pretty much fully developed by puberty, but recent research has determined that brain development during the teenage years is probably just as important as thebrain growth that takes place during a child’s first few years.
As Harvard neuroscientist, and mother of two teenage sons, Frances Jensen, explains, growth of the brain’s grey matter–neurons–is largely complete by age six, but white matter–axons, which serve as the wiring between brain cells–continues to develop into the 20s. As the teen brain is getting rewired, the axons are getting coated in myelin, a fatty material that acts as insulation to help signals move faster between brain cells. This rewiring and myelination process seems to impact the limbic system, which controls emotion, first, and doesn’t work on the rational, decision-making prefrontal cortex until late in the process. Thus, teens may have the calculating and decision-making skills of an adult, but this capacity is overridden and influenced during the teenage years by the more powerful limbic system.
Meanwhile, the teen pituitary system is releasing hormones that impact the limbic system, heightening emotions that may already seem overpowering due to the rewiring. As if this wasn’t enough to make it seem like an alien transplanted your teen’s brain,teenage brains are also more sensitive to the release of pleasure-inducing dopamine than adult brains are. A teen’s reasoning ability is thought to be almost fully developed by age 15, and teens can accurately determine dangerous activities. It’s just that teenagebrains are "more motivated by the rewards of taking a risk than deterred by its dangers. So even if they know something might be bad–speeding, drinking too much, trying new drugs–they get more pleasure from taking the risks anyway.”
So, what’s a parent to do? How do we raise our teenagers now that we know that they have the rational decision-making abilities of an adult, yet what seems like the emotional intelligence of a child? More rules and more involvement in their day-to-day lives–“tiger parenting,” or give them more freedom and let them be “free-range kids?” For the record, Jensen firmly adopted the former stance.
To learn more: check out this article about Jensen and her theories, along with an excerpt from her book: http://www.npr.org/blogs/health/2015/01/28/381622350/why-teens-are-impulsive-addiction-prone-and-should-protect-their-brains.