The analysis also found that significant health disparities exist between racial groups, and that Americans are less likely to have access to health care when they reach adulthood than they did during the teenage years.

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.

?Smoking, obesity, and alcohol abuse are leading contributors to preventable death in the United States,? said Duane Alexander, M.D., director of the National Institute of Child Health and Human Development, the NIH Institute that funded the analysis. ?By early adulthood, a large proportion of Americans smoke, are overweight, and drink alcohol to excess.?

Principal investigator Kathleen Mullan Harris, Ph.D., and her colleagues of the Carolina Population Center and the University of North Carolina at Chapel Hill, conducted their analysis using data from the National Longitudinal Study of Adolescent Health.

The National Longitudinal Study of Adolescent Health was designed to measure the effects of home, family, and school environment on behaviors that promote health. The study was undertaken in response to a mandate by Congress. Funding for the survey was provided by a grant from the NICHD with contributions from 17 other federal agencies.

?When they were young teenagers, most of the participants had fairly healthy behaviors,? said Christine Bachrach, Ph.D., Chief of NICHD?s 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 the current analysis, the researchers analyzed the responses of a nationally representative sample of more than 14,000 young adults who have been 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, Dr. Harris said.

?These trends are quite stunning,? Dr. 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, Dr. 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.