The U.S. military as a natural experiment: changes in drinking age, military environment, and later alcohol treatment episodes among veterans.

Before 1982, soldiers consumed alcohol legally on U.S. bases, regardless of age. By 1988, the military established policies to discourage underage and problem drinking and, along with the civilian population, fully transitioned to a 21-year minimum legal drinking age. We explored whether these changes were associated with changes in later alcohol treatment episodes among male veterans and civilians from years 1992 to 2003. Treatment rates for veterans and civilians were calculated using administrative databases for four age cohorts. Alcohol treatment rates were similar and odds ratios were > or = 1.0 for veterans compared with same-aged civilians in 1992; however, by 2003, veterans' treatment rates fell by 60% for ages 25 to 34 compared with a 20 to 25% reduction for civilians, and odds ratios fell to between 0.80 and 0.60 those of civilians. The military's concerted efforts to enforce the 21-year minimum legal drinking age were associated with greater reductions in later alcohol treatment episodes among veterans compared with civilians.