ROCKVILLE, MD -- By the time they reach early adulthood, a large proportion of American youth have begun the poor practices contributing to three leading causes of preventable death in the United States: smoking, overweight and obesity, and alcohol abuse, according an analysis of the most comprehensive survey of adolescent health behavior undertaken to date. The analysis also found that significant health disparities exist between racial groups. The National Longitudinal Study of Adolescent Health was designed to measure the effects of home, family and school environment on behaviors that promote health.

"When they were young teenagers, most of the participants had fairly healthy behaviors," said Christine Bachrach, chief of the National Institute of Child Health and Human Development’s (NICHD) Demographic and Behavioral Sciences Branch and project officer for the study. "What's really alarming is how rapidly healthy practices declined by the time the participants reached young adulthood."

For example, among young white women, the proportion reporting no weekly physical exercise was 5 percent during the adolescent years, but was 46 percent in early adulthood. Similarly, among white males, the proportion that was obese grew from 14 percent in the teen years to 19 percent when they became adults. Among female adults, blacks (55 percent) and Asians (53 percent) were the least likely to exercise, and among males, white and blacks were the least likely to exercise.

Researchers analyzed the responses of a nationally representative sample of more than 14,000 young adults who were followed since early adolescence. The survey respondents, recruited from high schools and middle schools around the country, were first interviewed from 1994 to 1995, when they ranged from 12 to 19 years of age, and again in 2001 and 2002, when they were 19 to 26 years old. The survey participants responded to questions on diet, inactivity, obesity, tobacco use, substance use, binge drinking, violence, reproductive health, mental health and access to health care. For nearly all groups surveyed, diet, activity level, obesity, health care access, tobacco, alcohol and illicit drug use and likelihood of acquiring a sexually transmitted disease worsened as the youth reached adulthood, principal investigator Kathleen Mullan Harris said. "These trends are quite stunning," Harris added. "Whether or not the trends will continue as they age, we don't know. But it doesn't bode well for their future health, especially if these habits become established." By the time they had reached adulthood, Harris explained, the participants were more likely to be obese, to frequently eat fast food and to be sedentary. They were also less likely to have health insurance, to receive health care when they needed it or to receive regular dental and physical health examinations. The authors reported "dramatic" increases in behaviors related to 3 leading contributors to preventable deaths. "These findings underscore the importance of ongoing preventive efforts related to smoking, poor diet and physical inactivity and alcohol consumption, early in the life course." Harris explained that she and her coworkers are now doing additional research on the data in the Adolescent Health study to determine why certain groups were more at risk for a particular unhealthy behavior than other groups. She added, however, that because the groups differed in their health behaviors, intervention programs to reduce unhealthy behaviors would likely have the greatest chances for success if they were individually tailored to meet the needs of each particular group.

The analysis appears in the January 2006 Archives of Pediatrics and Adolescent Medicine and was conducted by researchers at the Carolina Population Center and the University of North Carolina at Chapel Hill. The study was undertaken in response to a mandate by Congress and funded by a grant from the National Institute of Child Health and Human Development (NICHD) with contributions from 17 other federal agencies.