Alcoholism has become a "public health crisis" in the U.S. military, according to a new study requested by the Defense Department.

The Institute of Medicine found that 20 percent of active duty service members admitted they drank five or more drinks per day on a regular basis in 2008.

In the same year, 47 percent said they engaged in binge drinking, which is five or more drinks in one sitting for men and four or more drinks in one sitting for women, but not on a regular basis.

Ten years prior, the number of binge drinkers actively serving in the military was at 35 percent.

The report also revealed the Pentagon hasn't improved its outdated methods of dealing with substance abuse among service members.

"Better care for service members and their families is hampered by inadequate prevention strategies, staffing shortages, lack of coverage for services that are proved to work, and stigma associated with these disorders," said Charles O'Brien, with the University of Pennsylvania's Center for Studies of Addiction, the chairman of the study committee.

Though not as prominent of a problem, prescription drug abuse also increased. In 2002, only 2 percent of active duty personnel said they misused prescription drugs. By 2008, that number had risen to 11 percent.