Brain Development in Teenagers

Many parents of teenagers have probably wondered or asked outright, ̶0;What were you thinking?̶1; when a teen texts while driving or experiments with alcohol. The answer is that while teens may physically look very much like adults, their brains are still developing. Their undeveloped brains decrease their ability to control their impulses, make them self-centered and more susceptible to drugs, alcohol and sleep deprivation, according to a March 2010 National Public Radio report.

  1. The Teen Brain

    • At its most basic level, the human brain is composed of nerve cells -- called neurons -- and synapses, which are tiny gaps between neurons. Neurons communicate with chemicals called neurotransmitters that cross the synapse from one cell to another. In the teen brain, there are many fast-developing synapses, which make teens more excitable, but increases their ability to learn, according neurology researchers from Children's Hospital Boston, cited in a 2008 "Harvard Magazine" article. However, there are also parts of the brain that are not yet fully connected, such as the frontal lobe, where reasoning, planning and judgment take place. Teens also have less myelin, a substance that covers the nerve cells and helps them communicate, according to the American Academy of Child and Adolescent Psychiatry.

    Frontal Lobes and Gender Differences

    • The brain of a teenager is only about 80 percent developed. The human brain is divided into sections called lobes that mature from front to back. The frontal lobes are the last section to connect and are not completely connected until a person is between age 25 and 30. Boys' and girls' brains also develop differently, according to the magazine article. The section of the brain that processes information grows during childhood and then begins to get thinner. In girls, this peak occurs between ages 12 and 14, while in boys, the peak occurs about two years later.

    Stressors and Brain Chemistry

    • The teen brain is more vulnerable to external stressors such as drugs, alcohol and sleep deprivation because its chemistry is very responsive to the environment. The high level of reactivity makes teens able to learn new things easily, but a psychoactive drug can have a much stronger effect. In addition, the effects can stay with teens longer. Using marijuana on the weekend, for instance, can impair cell signaling for several days afterward, which makes learning more difficult. The article notes many teenagers are likely to be short on sleep, which is also important for learning and memory.

    Teen Brain Function

    • Brain imaging studies show the teen brain functions differently than the adult brain, according to AACAP. Teen brains are guided more by the amygdala, a brain structure that is responsible for instinctive reactions, fear and aggressive behavior. As a result, teens are more likely to act on impulse, get into accidents or fights and engage in risky behavior. They may also misread or misinterpret social cues and emotions and are less likely to think before they act or pause to consider whether there might be consequences from their actions.

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