THURSDAY, Sept. 8 (HealthDay News) -- The number of Americans using illegal drugs has continued to rise, reaching 22.6 million, or 8.9 percent of the population, in 2010, a new government survey shows.

The increase has largely been driven by more marijuana use, according to the U.S. Substance Abuse and Mental Health Services Administration. In fact, in 2010 some 17.4 million Americans were using marijuana, compared with 14.4 million in 2007, the researchers found. This is an increase in the rate of marijuana use from 5.8 percent in 2007 to 6.9 percent in 2010.

"I don't know why there is an increase in marijuana, but that almost explains the increase in drug use," said Peter J. Delany, director of SAMHSA's Office of Applied Studies. "That's the driving trend."

In addition, young adults appear to be the group showing the greatest increase in drug use. "The group that seems to be standing out among everybody is the 18- to 25-year-olds," Delany said. "These are the people who are going to college, starting in the workforce and starting families."

Illicit drug use among this group has gone from 19.6 percent in 2008 to 21.5 percent in 2010, a significant increase, Delany said.

"This is a whole group of people we haven't focused on. We have to intervene much earlier, before they get into trouble," he said.

"We need to take what we are learning about helping people reduce their alcohol and tobacco use and figure out how to apply that to these other drugs in our society," Delany added. "We need to intervene before they need treatment or go to jail."

The report, released Sept 8, includes the results of the latest government survey on drug abuse, which involved about 67,500 people from around the country.

"We stand at a crossroads in our nation's efforts to prevent substance abuse and addiction," SAMHSA Administrator Pamela S. Hyde said in a SAMHSA statement. "These statistics represent real lives that are at risk from the harmful and sometimes devastating effects of illicit drug use. This nation cannot afford to risk losing more individuals, families and communities to illicit drugs or from other types of substance abuse -- instead, we must do everything we can to effectively promote prevention, treatment and recovery programs across our country."

The illicit use of prescription painkillers has also been increasing, with most (55 percent) getting these drugs from a friend or relative. Only 4.4 percent of those using these drugs got them from a drug dealer, and less than 1 percent purchased them over the Internet, the report found.

There has been some improvement in reducing the use of some drugs, the researchers noted. For example, the number of people using methamphetamine has dropped by about half between 2006 and 2010, going from 731,000 to 353,000.

In addition, cocaine use has dropped from 2.4 million users in 2006 to 1.5 million users in 2010.

Also, there was a decrease in teen drinking between 2009 and 2010, from 14.7 percent to 13.6 percent. Tobacco use has also declined among teens, from 11.6 percent in 2009 to 10.7 percent in 2010, the researchers noted.

As seen before, fewer people are getting help for their drug abuse problem than need to, the researchers found. In fact, of the 23.1 million Americans who need specialized drug abuse treatment only 2.6 million are getting it.

Bruce Goldman, director of Substance Abuse Services at the Zucker Hillside Hospital of the North Shore-LIJ Health System in Glen Oaks, N.Y., said the report mirrors what he is seeing clinically.

"Alcohol is the number one drug people seek treatment for, cannabis has been and remains number two," he said. "What has changed is number three is prescription opioid abuse and/or heroin abuse as opposed to cocaine, which used to be number three."

While smoking has become less acceptable, drinking and marijuana don't seem to have the same negative image, Goldman said. "Where we need to put our focus is in changing attitudes, which takes a long time," he added.

On the plus side, drug addiction is seen as an illness, not a stigma, and treatments are available, Goldman said. "We have many more options in treating people with substance abuse disorders and there are effective treatments available," he added.

More information

For more on substance abuse, visit the U.S. National Library of Medicine.