For many young Americans, turning 21 means consuming a lot of alcohol -- so much so that half of women in a recent study drank more on that occasion than on any other day of their lives.

Excessive drinking in such a short period brings a variety of negative consequences, said Kim Fromme, PhD, of the University of Texas at Austin, speaking at APA's Annual Convention.

"It does appear that turning 21, and the 21st year, is probably a pretty high-risk time for drinking, driving and high-risk sexual behavior," said Fromme, who leads the UT Experience, a study tracking more than 2,200 University of Texas students from just after graduating high school to age 22.

In fact, 75 percent of students reported some type of negative consequence as a result of drinking on their 21st birthdays, Fromme said.

The health consequences of such celebrations are startling, the UT researchers have found. When they asked a sample of students to record their daily drinking behaviors for two weeks before and two weeks after the day they turned 21, they found that 44 percent experienced blackouts, with 39 percent not remembering how they had gotten home, and almost 5 percent reported having unprotected sex in connection with the celebration. Men consumed an average of 12 drinks, while women downed eight.

Alarmingly, 15 percent of the students admitted they had driven after drinking in the two-week period after they turned 21 - up from 9 percent before their birthdays.

"It appears that turning 21 is associated with driving to bars, hooking up and having more frequent unprotected sex," Fromme said.

-C. Munsey