Colorado’s rates of marijuana and cocaine use, alcohol consumption, and binge drinking are far higher than the national average and among the highest states in the nation, according to a federal survey.

Coloradans reporting marijuana use grew from previous surveys, which may add fuel to the ongoing debate over legal medical marijuana.

The number of young adults who said they had used marijuana in the past year was 38.5 percent in the Colorado survey, compared with a national average of 29.1 percent. The queries of more than 137,000 Americans were made in 2008 and 2009.

The number reporting pot use was up 3 percentage points from the last survey, in 2007 and 2008.

The state also had higher-than-average rates of people with a major depression episode or serious thoughts of suicide, according to the survey by the Substance Abuse and Mental Health Services Administration.

“There are a number of categories we’re in the top 20 percent, and this is one case where being in the top 20 percent is not a good thing,” said Arthur Schut, deputy director of the Arapahoe House behavioral treatment center in Thornton.

“It’s always worrisome when we look at Colorado and other mountain states for substance use and serious mental illness,” said Charles Smith, director of the behavioral health division of the state Department of Human Services.

Colorado is hurt by funding challenges in behavioral services and isolation from potential care in mountain and “frontier” communities, Smith said.

Legalizing medical marijuana in Colorado is another potential factor researchers are studying, he added.

“It’s early for us to kind of speculate, but we’re looking at that very closely,” Smith said.

Freeing marijuana sales is similar to past results from opening up liquor or other substances, Schut said. “It’s a rather simple formula. . . . You have larger consumption when you have more access. It appears we’ve increased access, and therefore we’ve increased consumption.”

The report says overall illicit drug use in the U.S. rose to 8.4 percent of the population ages 12 and over, from 8 percent in the previous survey. (Illicit drugs included marijuana, cocaine, painkillers used outside a prescription and other substances.) Reports ranged from a low of 5.3 percent in Iowa to 13.5 percent in Alaska. Colorado’s rate was 11.3 percent.

Nearly half of Coloradans ages 18 to 25 reported binge drinking in the past month, at 47.5 percent of the population, compared with 41.4 percent nationwide. Smith said it’s more than a college-age problem — Colorado also has high rates of Latino binge drinking, and state officials think they are making progress with targeted programs.

About 4.3 percent of Coloradans 18 and over had “serious thoughts of suicide” in the past year, higher than the national average of 3.7 percent. Smith said Colorado’s rate has long been worrisome but is in line with other mountain states such as Idaho, Montana and Wyoming with similar problems.

The key to altering Colorado’s trend is wider screening programs for substance abuse and early mental health signals, Smith said. A four-year grant has helped the state screen 100,000 patients through federal health clinics and primary doctors.

“In time, we’ll start seeing a lot of those numbers come down because we’re changing the culture,” he said.

Michael Booth: 303-954-1686 or mbooth@denverpost.com