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Adolescence is a period of rapid physical, emotional, cognitive, and social development. Generally, adolescence begins at age 11–12 years and ends between ages 18 and 21. Most teenagers complete puberty by age 16–18 years; in Western society, however, for educational and cultural reasons, the adolescent period is prolonged to allow for further psychosocial development before the individual assumes adult status. The developmental passage from childhood to adulthood includes the following steps: (1) completing puberty and somatic growth; (2) developing socially, emotionally, and cognitively, and moving from concrete to abstract thinking; (3) establishing an independent identity and separating from the family; and (4) preparing for a career or vocation.




In the United States in 2010, there were 22.0 million adolescents aged 15–19 years and 21.5 million aged 20–24 years. Adolescents and young adults (ages 15–24 years) constitute 14% of the US population. Between 1990 and 2006, the population 10–24 years of age increased from 40.1 to 63.3 million. In the next several decades, the proportion of racial and ethnic minority adolescents is expected to increase. It is projected that by 2040 the percentage of non-Hispanic whites will drop below 50% of the total adolescent population. Hispanics are becoming the second most populous racial and ethnic group of adolescents.




In 2010, there were 10,887 deaths among adolescents aged 15–19 years, representing a rate of 49.4 per 100,000. Cultural and environmental rather than organic factors pose the greatest threats to life. The three leading causes of death in adolescents aged 15–19 years were unintentional injury (41.7%), homicide (16.8%), and suicide (15.2%). The primary cause of unintentional injury death was motor vehicle crashes (63.8%), followed by poisoning (16.4%), which includes prescription drug overdoses and is the only unintentional injury mechanism to increase over the past decade. Homicide deaths were predominantly attributable to firearms (84.8%), while both firearms and suffocation were leading mechanisms of suicide death (40.3% and 45.3%, respectively). The mortality rate of adolescent males aged 15–19 was more than twice that of females (69.6 vs 28.1 per 100,000, respectively), largely due to higher rates of unintentional injury, homicide, and suicide death among males.


The rate of adolescent morality declined by 7.7% from the previous year and 26.4% from 2000. This decline may be largely attributable to decreases in unintentional injury. Motor vehicle crashes, the leading cause of death among teenagers in the United States, account for more than one-quarter of deaths in this age group. In 2010, approximately 2700 teenagers in the United States aged 16–19 were killed and almost 282,000 were treated and released from emergency departments (EDs) for injuries suffered in motor-vehicle crashes. Research suggests that the most comprehensive graduated drivers licensing (GDL) programs, designed to delay full licensure while allowing teenagers to get their initial driving experience under low-risk conditions, are associated with reductions of 38% and 40% in fatal and injury ...

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