"While these data confirm the reduction in underage drinking rates since the 1970s, they also underscore the need to redouble our efforts against this important problem," says Ting-Kai Li, M.D., Director of the National Institute on Alcohol Abuse and Alcoholism at the NIH. "The authors have demonstrated an important means for monitoring long-term changes in alcohol use patterns that will serve us well in these efforts."
Since 1975, information about drinking by persons age 18 and younger has been collected by a number of ongoing national surveys, including the Monitoring the Future (MTF) study, the Youth Risk Behavior Survey (YRBS), and the National Household Survey on Drug Abuse (NHSDA). These surveys have shown that almost 80 percent of adolescents have consumed alcohol by the time they are 12th-graders, and that about 12 percent of 8th-graders have consumed five or more drinks on a single occasion within the past two weeks.
Although year-to-year differences in drinking patterns in these surveys are often statistically significant, such short-term comparisons provide little useful information about long-term trends, or changes in drinking habits over multi-year periods.
Lower Drinking Age Had an EffectIn the current study, researchers Vivian B. Faden, Ph.D., of the NIAAA, and Michael P. Fay, Ph.D., of the National Cancer Institute applied "joinpoint" statistical methodology to analyze trends in youth drinking data collected in three surveys: the MTF, the YRBS, and the NHSDA. Joinpoint analysis uses sophisticated statistical methodology to look at all available years of data from a survey simultaneously to identify significant changes in direction in trends.
"We applied this technique to three different surveys to see if joinpoint statistics tell the same story in terms of trends across surveys," explains Dr. Faden, Associate Director of NIAAA's Division of Epidemiology and Prevention Research. "This approach reveals information about trends in underage drinking heretofore unavailable, and strengthens the conclusions we draw regarding underage drinking trends."
The analyses showed an increase in youth drinking in the late 1970s, followed by a long period of decreases until the early 1990s. The authors note that the decline in underage drinking rates during this period probably reflects the increase in the minimum legal drinking age from 18 to 21. Since the early 1990s, all three surveys included in this analysis indicate relatively stable prevalence rates for underage drinking.
Almost Half of High School Seniors Drink"Stable is better than up," notes Dr. Faden. "However, the current stability in youth drinking prevalence is quite worrisome."
Rates for any alcohol use in the past 30 days range from 19.6 percent of 8th graders to 48.6 percent of 12th graders. The data also show that more than 12 percent of 8th graders and nearly 30 percent of 12th graders report drinking five or more drinks in a row in the past two weeks.
"Much remains to be done to get those numbers moving down again," says Dr. Faden. "We need to re-examine the approaches we have taken to prevent underage drinking, so that in another ten years we can report a downturn in this high-prevalence behavior instead of a stable situation."
As policy makers implement strategies to target underage drinking, the kind of trend analyses demonstrated by Drs. Faden and Fay will help provide the most comprehensive and reliable information on trends in alcohol use by underage drinkers.