Early puberty tied to risky behavior.

KOLOA, HAWAII -- The earlier onset of puberty, combined with a fairly delayed set of processes that underpin cognitive development, might represent a key framework for understanding the risky behavior of adolescents, Dr. Ronald E. Dahl said at the annual meeting of the American College of Psychiatrists.

It has been clear for some time that the hormonal surges that lead to puberty are beginning earlier. However, the maturation of cognitive control and the capacity to regulate behavior are still developing throughout adolescence and into early adulthood--a fact that poses new affective challenges for young people. This creates a maturational gap that leads to extra burdens and challenges with direct clinical relevance, Dr. Dahl said later in an interview.

"This probably contributes to higher rates, and [an] earlier age of onset, of some behavioral and emotional problems--not only in terms of risky and reckless behavior, but also in relation to the onset of affective disorders in adolescence," Dr. Dahl, Staunton Professor of Psychiatry and Pediatrics at the University of Pittsburgh, said at the meeting.

Furthermore, this gap is wider among adolescents in contemporary society, compared with a relatively shorter interval of adolescence in traditional societies, he noted.

For example, in the book, "Adolescence: An Anthropological Inquiry" (New York: Free Press, 1991), Alice Schlegel and Herbert Barry III discuss a comprehensive anthropological study of adolescence across 185 traditional societies that found a 2- to 4-year gap between the onset of puberty and the taking on of adult roles.

In contrast, young people in contemporary societies often experience an 8- to 12-year interval between the onset of puberty and taking on full adult roles and responsibilities. Thus, adolescence as a developmental period has been extended in recent history.

Within this framework, it is important to consider the early emotional and motivational changes that occur naturally at the onset of puberty.

These changes include increases in sensation seeking, sexual interest, appetite, and novelty seeking, as well as greater intensity in some emotional responses. These intensified emotions and motivations can lead to risky behavior, but they also can provide passion for positive interests, including sports, science, literature, art, music, idealism, and the desire to care for others.

Meanwhile, Dr. Dahl added, "most measures of cognitive development correlate with age and experience." These developments include logic, inhibitory control, planning, problem-solving skills, and the ability to understand what might be the long-term consequences of behavior.

Along with the maturational gap, adolescents experience a circadian shift that naturally makes them want to stay awake later at night and sleep later in the morning. High school students have an average bedtime of 11:30 p.m., but because the daily school schedule requires them to wake up each weekday morning at an average of about 6:15 a.m., many youths usually are sleep deprived. More than 15% of high school students say they average 6 hours of sleep per night when school is in session, while the overall average is 7.5 hours at a time in development when youth require 8-9 hours of sleep for optimal function. The natural tendency of adolescents to stay up later coincides with an increasing late-night access to stimulating technology, Dr. Dahl observed. About 90% of teens have, in their bedrooms, a radio or MP3 player, 57% have a television, 43% have electronic or video games, and 42% have a cell phone.

Meanwhile, 75% of adolescents drink caffeinated beverages most days, including 31% who drink two or more such beverages per day. As a result of all these factors, a large proportion of high school adolescents do not get enough sleep on school nights.

This is a time in life, however, when teens need more sleep, he said. The sleep deprivation mars their ability to make the necessary cognitive adjustments that help them regulate their behavior. This leaves them vulnerable to strong emotions that lead to risky behavior. Adolescents can be sleepy, irritable, and inattentive, states that affect learning and memory and increase difficulties with cognitive-emotional integration. The neurobiologic changes contribute to what Dr. Dahl called a "health paradox" in adolescence: On the one hand, the teenage years represent--physically--the healthiest period of the human life span.

Compared with children, teens show improvements in strength, reaction time, reasoning capabilities, and immune function. Yet overall morbidity and mortality rates soar by 200%-300% between childhood and late adolescence. For example, in 2003, about 7,000 U.S. children aged 5-14 years died of all causes, compared with about 33,500 teens and young adults aged 15-24 years.

Another consideration in the drive toward adolescent risk-taking behavior may be related to a natural increase in status seeking, Dr. Dahl said.

In the interview, Dr. Dahl said this model has clinical implications for early intervention. "This is especially the case for cognitive-behavioral treatments that help youth learn skills in behavioral control and emotion regulation," he said.

BY GREG MUIRHEAD

Contributing Writer