In 2006, about 1,600 people sought treatment, compared to more than 2,400 the year before. Carol Falkowski, the author of the report, says says there are other indicators that show decreases, as well.
"First are meth labs, and we believe that this is attributable to the restrictions on the sale of Sudafed products," says Falkowski. "The second thing that's going down, though, are people coming in to hospital emergency departments for meth. And we can only hope that this reflects fewer people using methamphetamine."
The declines come after years of increases.
But law enforcement agents fighting meth sales and use said they've yet to see evidence of major declines.
"I can tell you meth is still the No. 1 drug we see coming in, and it's coming in just as fast as before," said Terri Vandergriff, special agent in charge of narcotics for the state Bureau of Criminal Apprehension.
"Maybe Hazelden can see something that hasn't showed up for us yet," she said. "But so far the (federal) Drug Enforcement agency, the BCA, the State Patrol and local law enforcement aren't seeing a drop. It's still an awful problem."
Vandergriff said the meth labs that have disappeared were mostly the "mom and pop labs, very small operations. By far, the meth we see here is made in Mexico and brought here by gangs in California, Texas or Arizona."
The Hazelden study points out other worrisome trends. It says there has been a gradual increase in the number of people seeking treatment for narcotics other than heroin and methadone. And more people are seeking treatment for marijuana than any other illegal drug.
(The Associated Press contributed to this report)