The Adolescent Brain and Social Policies

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“A decade ago, the prevailing notion was that brain growth ended at about the age of 2 years. Since then, we have learned that brain growth continues well into adolescence (between ages 10 and 19) and into young adulthood (see the figure below). During this period the brain undergoes a series of changes, and parts of the brain associated with social skills, problem solving, and identifying emotions mature only by the early twenties. However, this process of brain development cannot entirely explain adolescent decision making and behavior. Nor does it override the effect of the environment—parents, schools, communities—in which young people live.

Brain development: arborization and pruning
The brain is made up of nerve cells—about 10 billion of them—connected by branches or dendrites. These branches move information from one cell to another, but these connections are not soldered together; rather, there are spaces between the branch of one cell and the body of another. These spaces are called synapses, and information moves from cell to cell across these spaces by releasing tiny packets of chemicals. When there are abnormalities in the chemicals in the synapses, a variety of clinical conditions result, such as depression and attention-deficit and hyperactivity disorders.

Different parts of the brain handle different activities—that much is well-known. What is new is the finding that during adolescence certain areas of the brain grow in size and other regions become more efficient. For example, the area of the brain responsible for language more than doubles in size between ages 8 and 14. Consequently, language acquisition is optimal at those ages. So, too, connections grow and strengthen between the brain stem and the spinal cord, increasing the connections between the emotions and what the body feels. Throughout childhood and adolescence, more and more nerve cells grow sheaths around them called white matter or myelin. This is like building a superhighway, allowing information to be interpreted and recalled much faster than was ever possible as a young child.

These structural changes are only some of the brain’s alterations during adolescence. Another major change is called “pruning.” Throughout early childhood, the number of connections between cells increase, and because the process is much like the growth of branches on a tree, it is called arborization. It allows a child’s brain to be very excitable—which is why children seem to be perpetual motion machines. In adolescence, many of those branches die—through pruning. The brain is less excitable but also more efficient in carrying information.

The pruning follows a consistent pattern throughout adolescence and young adulthood starting at the back of the brain and ending at the prefrontal cortex. The prefrontal cortex regulates impulses, risk taking, planning, decision making, empathy, and insight. Research also shows that the cerebellum, recently discovered to be important for mathematics, music, decision making, social skills, and understanding
humor, continues to grow through adolescence and well into emerging adulthood. The last structure of the brain to stop growing, it develops until the mid-twenties.

Implications for social policies
What does this new brain research mean for understanding adolescent decision making and behavior? Although much more research is needed before defi nitive policies can be recommended based on the new brain research, it suggests some interesting policy considerations:

• The loss of neuronal excitation in adolescence is associated with a rise in depression, especially among adolescent females, suggesting a biological basis for the epidemiological finding that gender differences in depression start around the time of puberty. These biological changes combine with external sources of stress to increase the risk of suicide for youth in many countries of the world.
• As the brain matures during adolescence, alternations in the synaptic chemicals may influence learning (drugs for attention-deficit disorders improve information transfer at the level of the neuronal synapse). For example, antidepressive drugs may allow for certain excitatory neurotransmitters to stay in the space between two brain cells longer than otherwise.
• Learning and teaching strategies should be timed to increase neurodevelopmental capacities. Because neurodevelopmental maturation occurs at different chronological ages for different people, their inability to grasp a concept at one age does not mean that they are unable to learn the material. This speaks to the risk of educational “tracking” based on comprehension or performance examinations at a young age.
Without a fully mature prefrontal cortex, adolescents may be more impulsive than adults and perhaps more susceptible to peer influences. This impulsiveness—especially in reactive decision making, as when faced with a situation or threatened to make an immediate decision—suggests the value of second chance programs.

It is, however, too early in the research to draw definitive conclusions about brain development and behavior. Also, physical development interacts with the social environments to determine behaviors and outcomes. So parental behaviors and expectations, effective schools, communities that are youth oriented and supportive, all make a difference in determining young people’s behavior and how well they learn complex decision-making skills.”

Source- World Development Report 2007, Box 2.9 ‘Brain development among youth: Neuroscience meets social science’, p.61 (emphasis mine)

Eye gaze and cognition in children
Glazed looks sharpen the mind
Universities: A social duty
Into the Mystery of the Adolescent Mind
A Study of Interactions: Emerging Issues in the Science of Adolescence Workshop Summary
The 7 Habits of Highly Effective Teens

World Development Report 2007 links;
Graphs from the report
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This page contains a single entry by Paul published on September 16, 2006 4:16 AM.

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