Miley Cyrus’ parents, take note: It’s probably not all your fault.
Thanks to emerging adolescent brain research, we are learning that many reckless, erratic, downright befuddling teen behaviors (twerking, et al) might have more to do with their not-yet-fully mature brains than just bad parenting.
Many behaviors once chalked up to hormones, immaturity, laziness and over-coddling are rooted in our adapting brain chemistry and structure.
For example, the prefrontal cortex, the master control center of the mind, doesn’t fully mature until our mid-20s. Researchers have even lengthened what we consider our “adolescent years,” which they say now runs from age 12 to 24.
This sheds a new perspective on our favorite trainwreck, Lindsay Lohan, whose long list of DUIs, car crashes, shoplifting, tantrums, drug use and other misadventures mostly occurred before her 25th birthday. How much of her unyielding impudence had to do with an immature brain?
In “Brainstorm: The Power and Purpose of the Teenage Brain” (Tarcher) a new book by UCLA clinical psychiatrist Daniel Siegel — who also has two teens at home — readers glimpse into the adolescent mind and learn how to deal with their teens with a better understanding of brain science.
During this key time in brain development, there’s a “burst of growth and maturation taking place as never before in our lives,” Siegel writes.
The mind is in a “renovation” mode, creating a tinderbox of emotions that can at least partially explain why teens are so difficult when you ask them to clean their room.
‘Pruning’ the toddler mind
Though brain maturation depends on a host of influences, both environmental and genetic — everything from heredity to nutrition to sleep patterns — all healthy adolescent brains follow a similar blueprint of maturation.
As toddlers, there is an overabundance of synapses — or connections between neurons — in the brain. These connections are necessary to comprehend a world where everything is new and must be learned. Before we can even walk, there are twice as many synapses in the brain than in adulthood.
But this crowded brain that works so beautifully for us in childhood cannot sustain us into our later years.
What follows is a “second wave” of change, where the brain is honed into a lean machine with fewer but stronger connections.
As we enter adolescence, some synapses are pruned in favor of others we use more frequently. (This explains why language acquisition begins to taper off once we hit age 12, as the areas of our brain responsible for learning new languages are trimmed in favor of other areas.)
Each year, gray matter is cut down at a rate of .7% a year, a reduction that continues into our 20s.
A second process, called myelination, occurs in tandem with pruning. Myelin, like grease for the wheels of a neuron, cover the connections among neurons, enabling the passage of electrical flows — creating a quicker, more streamlined mental responses.
During teen years, myelination jumps a whopping 100%, according to science writer Barbara Strauch, author of “The Primal Teen.” An interesting aside, and perhaps one of the reasons girls tend to mature faster than boys, is that they tend to myelinate at faster rates than boys do.
The combined effect of myelination and pruning allow various areas of the brain to better integrate and work together, creating “more precise and efficient connections in the brain” that create “wiser judgment and discernment” and an overall appreciation for the “bigger picture,” writes Siegel. In other words, we are establishing a brain that is far better capable of dealing with the grown-up world.
This is the end goal — but in the process of creating a more efficient machine, the mind has some kinks to work out.
The brain remains “under construction, thus making it difficult to think critically and rationally before making complex decisions,” concludes a paper called “Maturation of the Adolescent Brain” published this year in the journal of Neuropsychiatric Diseases and Treatment.
Unfiltered reactions
It’s not just that the brain is “under construction,” it’s where this construction occurs that helps explain teen behavior.
Though pruning and myelination occur all over — in the brain stem (basic functions like breathing and sleeping), cerebellum (motor control) and the occipital lobes (vision) — these processes primarily hit the frontal lobes and limbic system.
Does your teen eschew writing his college essay in favor of hanging out at the mall with his friends?
Blame the prefrontal cortex — at least a little.
That master control center orchestrates complex cognitive and social behaviors, like planning for the future. The most frontal part of the brain helps create “self-awareness, empathy, emotional balance and flexibility,” Siegel writes.
Mess with the prefrontal cortex and you get Phineas Gage, one of the most famous patients in medical history.
While working as a railroad foreman in 1848, Gage’s frontal lobe was damaged when a iron rod penetrated his skull. The once pleasant, religious man turned angry, inappropriate, even rude after the accident. Though he survived, friends complained, “He’s no longer Gage.”
Teenagers, one might argue, are like mini-Gages, exhibiting “brainstorms” in their prefrontal cortexes that cause behavior that deviates from their normal personalities.
“[Adolescents] may be more fragile, more easily disrupted than they will be in the years ahead,” Siegel writes. “Without the calming influence of that cortical region, sudden outbursts of limbic lava and brain-stem bursts of reactivity — the ancient reactions of fright, flight, freeze or faint — can emerge suddenly, sometimes without warning.”
This “limbic lava” — a poetic term for the collection of structures that make up the limbic system, or the emotional center of the brain that houses the amygdala, the “flight or fight” area — is also in flux during adolescence and is not kept in check by the prefrontal cortex as it is in our adult years.
Teens have a “faster route” from the amygdala than do adults, according to brain-scan studies. For adults, amygdala response first passes through the higher cortexes before being translated into action. For teens, the cortex often is bypassed entirely.
This results in the more reflexive, impulsive behaviors so characteristic of teen years. Adding to this is the fact that sex hormones are especially active in this area, causing those over-the-top temper tantrums.
Is this just nature’s way of making parents suffer?
Not completely. There is significant evolutionary benefit to a more direct amygdala response when you’re young, Siegel writes, quoting the book “Zoobiquity” that covers the behavioral connections between humans and animals:
“A similarly lowered risk threshold — indeed, a new pleasure in risk taking — likely propels nearly grown birds out of nests, hyenas out of communal dens, dolphins, elephants, horses and otters into peer groups, and human teens into malls and college dorms.”
Agression and laziness
Unfortunately, there’s a downside to the unfiltered “fight or flight” response.
“What this means is that the intense emotions of a pure amygdala response may rise up even when nothing is shutting off the cortex, as when we’ve flipped our lids in an agitated chaotic state or in a shut-down, rigid state,” Siegel writes.
For example, when researchers show adults a hostile face, their amygdala reacts. Not so when they’re shown a neutral face.
But show teens a neutral face, and the amygdala still lights up.
“The result for teens can be an inner sense of conviction that even another person’s neutral response is filled with hostility and he cannot be trusted,” Siegel writes.
In other words, your kid doesn’t have a persecution complex — it’s their amygdalae’s fault.
Perhaps the cingulate gyrus is to blame, too, points out Strauch in “Primal Teen.”
The cingulate gyrus, part of the limbic system, helps to coordinate external stimuli with emotions and also regulates aggression — and, no wonder, this area is still heavily myelinating in adolescence.
“If that area is still being built during the teenage years, could this help explain some of the bumps and blips of adolescence? If the connections between gut reactions and intelligent responses are not yet wrinkle-free, could that be one reason an otherwise polite 14-year-old boy flips out when asked to, say, take out the garbage?” Strauch writes.
And maybe it explains why teenagers just can’t get themselves off the couch.
Myelination also occurs in the nucleus accumbens, a region in the frontal cortex, that helps to direct motivation, which means that this area of the brain is still under construction. In one brain study, researchers found that teenagers have less activity here than their parents do, again providing some scientific evidence for teen laziness.
Chemical imbalances
Brain structure is only part of the story, Siegel writes. Adolescents are also going through a multitude of changes in their brain chemistry, too.
Serotonin, a key neurotransmitter, sometimes referred to as the “Don’t Panic” neurotransmitter and the basis for Prozac, helps in mood and impulse control, anxiety and arousal — and is in short supply in the teen mind.
This, at least in part, helps to explain the impulse-control issues we’ve all likely experienced during our teen years. Even rhesus monkeys show similar effects of low serotonin. In one study, rhesus monkeys with low serotonin — about 10% of the group — showed more impulsive actions and aggression.
What about sleep issues so evident when you’re trying to wake a teen up for school? Melatonin is to blame.
Melatonin, a chemical that helps regulate circadian rhythms and the sleep-wake cycle, is out-of-whack in teenagers. The chemical begins to secrete up to two hours later at night in adolescents than in adults — around 10:30 p.m. in teens — meaning they get tired later, then stays in the brain longer, making them sleepy in the morning, explains Siegel.
But perhaps the biggest culprit in teen drama is the neurotransmitter dopamine.
Dopamine aids in “movement, emotional response, and the ability to experience pleasure and pain,” Siegel says. The base levels for dopamine are lower in adolescents than in adults.
But lower dopamine doesn’t equal a reduced response. In fact, it might explain those nasty mood swings.
When dopamine is released in the system, it’s perhaps more rewarding because there’s less of it to start with, making those spikes of pleasure all the more intense.
“When your dopamine circuitry is turned way up, it’s like an amplifier with its gain turned up,” writes Siegel. This urges adolescents to “gravitate toward thrilling experiences and exhilarating sensations” often without a thought (without the help of the prefrontal cortex) to the negatives.
This also creates a behavior that Siegel calls “hyper-rationality,” where you “examine the facts of a situation and don’t see the big picture.”
“Studies reveal that as teens we are often fully aware of risks, and even at times overestimate the chance of something bad happening; we simply put more weight on the exciting potential benefits of our actions,” he says.
Take this one step further, and it might just explain why teens are so prone to drug and alcohol abuse. Once attributed to peer pressure, new studies indicate that dopamine might also contribute addictive substances and behaviors — drugs, alcohol, even food — involve the release of dopamine. When say, dopamine levels are increased by drinking alcohol, they plummet when the booze wears off, making the drinker want more. And if that drinker is a teen, the plummeting feeling can be all the more intense.
This might also explain why many teens report feelings of boredom unless they are thrill-seeking or doing something new.
Teen romance
This dopamine pleasure circuit even plays a role in the “love high” we’ve all experienced — and might explain why teens fall so much harder.
“Teenagers are attracted to risk,” writes Strauch in “The Primal Teen. “And love might be just the kind of ‘risk’ their brains like.”
Much like the evolutionary benefit of fast-acting amygdala response, there seems to be a developmental upside to these out-of-whack dopamine levels.
In addition to increasing risk-taking (the “get out of the nest” instinct), these behaviors might also translate into better mating options, especially for males, whose dopamine remodeling phase is more pronounced, points out psychology professor Laurence Steinberg in his paper “A Social Neuroscience Perspective on Adolescent Risk-Taking.”
“Individuals inclined to take such risks were differentially advantaged when it came to surviving and producing descendants who would themselves survive and reproduce,” he writes.
“Natural selection would favor the preservation of inclinations toward at least some risk-taking behavior during adolescence, when sexual reproduction begins.”
In other words, when it comes to all that sexting, gossiping and recklessness — there’s a method to the teen madness.