WEDNESDAY, Sept. 14, 2005 (HealthDay News) -- Seeking to determine how accurately college undergrads gauge their consumption of alcohol, a new study find students' so-called "self reports" are fairly correct.
In earlier studies, researchers at Duke University had used a laboratory setting to ask students to pour what they thought were standard-sized drinks, and found the students consistently poured larger amounts of beer, wine and hard liquor. This led the researchers to think students tended to underestimate how much alcohol they drank on a given night.
However, a subsequent field study done late one evening on the Duke campus, when researchers collected breathalyzer readings as well as self-reports of how many drinks the students had drunk that night, revealed the students' blood alcohol concentrations were reasonably close to levels that would be found in the number of drinks the students reported consuming.
"This data suggests that surveys [of students' self-reported drinking habits] are useful in collecting data about drinking habits," said study author Aaron White, an assistant professor in the department of psychiatry at Duke University and corresponding author of the study.
The findings appear in the September issue of the journal Alcoholism: Clinical & Experimental Research.
Another expert on the subject, Henry Wechsler, director of the Harvard School of Public Health's College Alcohol Studies Program, bases most of his work on self-reported drinking surveys among students.
"While this [the Duke research] is a provocative study, I can't fairly accept it as definitive proof of [the accuracy of self-reporting] because it is based on a small sample at one school," he said. "It needs further study."
For the field study, White and his colleagues collected breathalyzer readings and self-reported drinking data from 152 Duke students -- 104 men and 48 women -- who were walking on campus between 11 p.m. and 2 a.m. during the fall of 2004.
Comparing the self-reports of the number of drinks the students said they had with breathalyzer results, the researchers found that the students' blood alcohol concentrations (BACs) accurately reflected the alcohol that would have been in the drinks.
The average BAC levels among the students was 0.09 percent, which is above the 0.08 percent limit in most states for driving. The most accurate BACs were reported by the men and by those who drank beer rather than wine or spirits. The accuracy of the estimated BAC levels decreased as the number of drinks and the amount of time spent drinking increased.
White said that while the field study results were encouraging, they didn't address whether the students had gotten their drinks from restaurants, bars or containers, which serve standard-sized portions, or from off-campus private parties where students often pour much larger drinks for themselves.
"The study was done on campus. If we had looked at off-campus parties, we might have had different results," he said.
The bottom line, White said, is that students need to be educated about standard drink servings so they can better monitor their alcohol consumption.
"The simple fact is that we have so many kids who don't know about alcohol serving sizes. Educating them about serving sizes is getting more and more important," he said.
In another small study looking at the impact of alcohol on teens, Duke researchers found that parts of the brain that are involved in complex thinking and emotional control are smaller in teens who abuse alcohol than in those who do not.
The researchers said it's not clear whether alcohol abuse at a young age is the cause of the smaller size of this part of the brain, called the prefrontal cortex. It could be that this region, which governs thinking, planning and emotional control, increases the risk for alcohol abuse, they said.
The study results also appear in the appear in the September issue of Alcoholism: Clinical & Experimental Research.
For more on the dangers of alcohol abuse, visit the National Institute on Alcohol Abuse and Alcoholism.