Drug use among teens has dipped nationwide but underage drinking persists, with jumps in California and Wisconsin, according to a study released Thursday.

The report by the U.S. Substance Abuse and Mental Health Services Administration, based on interviews of 135,500 people, is the first to document state-by-state drug and alcohol use from 2002 to 2004.

It found that in 2004, 10.9 percent of young people age 12 to 17 reported that they had used an illegal drug in the past month, a drop from 11.4 percent in 2002.

Fueling the decline were six states — Illinois, Nebraska, North Carolina, South Dakota, Vermont and Virginia — while use in other states was largely flat.

At the same time, teen alcohol use remained basically unchanged — from 17.67 percent in 2002 to 17.65 percent in 2004. Among the youths age 12 to 20, California drinkers rose from 24.7 percent to 26.3 percent, while Wisconsin increased from 34.7 percent to 38.3 percent.

"While we are making progress on drug and alcohol use among youth, underage drinking continues as a stubbornly persistent problem," said Charles Curie, administrator of SAMHSA. "It's time to change attitudes toward teen drinking from acceptance to abstinence."

"It begins by recognizing the importance of parents talking to their children early and often about alcohol, especially before they've started drinking," he said.

The report showed wide disparities from state to state when it came to tobacco use as well as abuse of alcohol and drugs, including cocaine, marijuana and the non-medical use of pain relievers.

Alaska and New Mexico topped the list among those ages 12 and older who reported using an illegal drug in the past month, at 11.8 percent and 11.3 percent, respectively, compared to a national average of 8.1 percent. The most drug-free were Mississippi (5.8 percent) and Iowa (6.5 percent).

Among teens, tobacco-producing state Kentucky as well as South Dakota had the most tobacco use at 24.3 percent and 21.3 percent, respectively, compared to a national average of 14.4 percent. The lowest were Utah (8.7 percent) and the District of Columbia (9 percent).

Other findings:

--West Virginia had the highest rate of self-reported "serious psychological distress" among adults age 18 and older in the past year (12.7 percent), while Hawaii had the lowest (7.1 percent). The study did not track distress among youth.

Ten states registered gains: Arizona, California, Florida, Illinois, Iowa, New Jersey, Pennsylvania, Texas, West Virginia and Wyoming.

--Eight states ranked in the top fifth for underage use of alcohol as well as underage binge use: Iowa, Massachusetts, Montana, New Hampshire, North Dakota, Rhode Island, South Dakota and Wisconsin.

Douglas Wright of SAMHSA, who authored the study, said the results show that states need to review their individual findings carefully so they can tailor anti-drug and alcohol efforts accordingly. In general, colder, more rural states in the north may need to be particularly vigilant, he said.

"States tend to have drinking and other problems as you go further north, where a large portion of the year you are removed from a lot of other people," Wright said.