Indeed, in every generation, it seems, the same lament goes forth from the parents of adolescents: "What’s the matter with the kids today?" Why are they so often confused, annoying, demanding, moody, defiant, reckless? Accidental deaths, homicides, and binge drinking spike in the teenage years. It’s the time of life when psychosis, eating disorders, and addictions are most likely to take hold. Surveys show that everyday unhappiness also reaches its peak in late adolescence,
It’s not a question of intellectual maturity. Most studies show that abstract reasoning, memory, and the formal capacity for planning are fully developed by age 15 or 16. If teenagers are asked hypothetical questions about risk and reward, they usually give the same answers as adults. But the emotional state in which they answer questionnaires is not necessarily the one in which they make important choices. In real life, adolescents, compared to adults, find it more difficult to interrupt an action underway (stop speeding); to think before acting (learn how deep the water is before diving); and even to choose between safer and riskier alternatives. It is easy for them to say that they would not get into a car with a drunk driver, but more difficult to turn down the invitation in practice. Adolescents’ judgment can be overwhelmed by the urge for new experiences, thrill-seeking, and sexual and aggressive impulses. They sometimes seem driven to seek experiences that produce strong feelings and sensations.
Resisting social pressure is also difficult for teenagers. Much of their troubling behavior, from gang violence to reckless driving and drinking, occurs in groups and because of group pressure. In a psychological experiment, adolescents and adults took a driving simulation test that allowed them to win a reward by running a yellow light and stopping before they hit a wall. Adolescents, but not adults, were more likely to take extra chances when friends were watching.
Beginning at puberty, the brain is reshaped. Neurons (gray matter) and synapses (junction between neurons) proliferate in the cerebral cortex and are then gradually pruned throughout adolescence. Eventually, more than 40 percent of synapses are eliminated, largely in the frontal lobes. Meanwhile, the insulating coat of myelin on the axons that carry signals between nerve cells continues to accumulate, gradually improving the precision and efficiency of neuronal communication – a process not completed until the early 20s. The corpus callosum, which connects the right and left hemispheres of the brain, consists mainly of this white matter.
Another circuitry still under construction in adolescence links the prefrontal cortex to the midbrain reward system, where addictive drugs and romantic love exert their powers. Most addictions get their start in adolescence, and there is evidence that adolescent and adult brains respond differently to drugs. Studies have found that adolescents become addicted to nicotine faster and at lower doses. Functional brain scans also suggest that teenagers and adults process reward stimuli differently; the adolescents are hypersensitive to the value of novel experiences.
At least in the US, one important social policy conclusion may have been drawn in part from the neuroscience researches on the adolescent brain. Last year, the US Supreme Court, affirming a Missouri high court decision, declared by a vote of 5-4 that the execution of 16- and 17-year-olds is an unconstitutionally cruel and unusual punishment. The minimum age for capital punishment in the US is now the same as the minimum age for voting and serving on juries. In writing their decisions, the justices referred to evolving standards of decency, practices in other countries, the immaturity of adolescents, and their greater potential for change. They did not specifically mention brain research, but they had the opportunity to read friend-of-the-court briefs citing the results of different researches that were submitted by the American Bar Association, American Academy of Child and Adolescent Psychiatry, and American Psychiatric Association, among others.
In the Philippines, it is noteworthy to cite a new law, Republic Act No. 9344, which exempts those 15 years and below from any criminal liability. RA 9344, or the Juvenile Justice and Welfare Act of 2006, provides that youth offenders aged 15 years and one day up to 18 years old can only be criminally charged if they acted out the crime with discernment. It came into effect last May 22, 2006.
Some critics, even if they welcome the US Supreme Court decision and our own new Juvenile Justice and Welfare Law for other reasons, have complained that the new basic, clinical and laboratory researches stereotype adolescents and provide a biological rationalization for irresponsible behavior. Animal experiments, they point out, have limited value because laboratory animals do not undergo a lengthy human childhood. And human brain development does not unfold automatically and uniformly. There is much individual variation that reflects experience as well as genetic programming. The problems of teenagers are not all in their brains but have many causes, social and individual, genetic and environmental. At present and probably for a long time, researchers will be getting better information on the mental and emotional development of adolescents from interviews, observations, and behavioral tests than from animal research.
Neuroscience researches are becoming more sophisticated. There are already long-term studies in which people undergo frequent periodic scans over the course of their lives. The results are being used to investigate the effects of behavioral and cognitive therapies on attention deficit disorder and reading deficiencies in adolescence. Scientists are also looking at typical adolescent brain development to provide clues to the ways in which things go wrong. Someday, these researches may provide better answers as to why teenagers act the way they do. We will then be able to provide more effective treatments to this "teenage turmoil."