Not only do methamphetamine users have to struggle to overcome the insidious chemical effects of the powerful drug, but they also must deal with the perceived hopelessness of their addiction.

Word on the street – and in research labs – had for years imposed something of a life sentence on meth addicts. Many of the effects of the stimulant, it was believed, were permanent. Once you were hooked, your brain function remained impaired, circuits singed to the core.

But in a recently released study, UC Davis researchers who tested 65 recovering meth addicts for cognitive control have found that improved brain function, including a restoration of impulse control, is evident after a year without the drug.

The study, published in the Journal of Substance Abuse Treatment, gives hope to addicts who still feel intense cravings for the drug months after detoxification and rehabilitation treatment. But it also should be considered by public health officials when determining the length of programs for meth addicts, says Dr. Ruth Salo, a UC Davis assistant professor of psychiatry and behavioral sciences, and the study's lead author.

"I think this is a really powerful piece of information to take into a recovery program," Salo says. "It is possible there still are some functions of the brain that don't recover. Some people did believe that, once you'd used, the damage was permanent. But the brain is very resilient."

Salo's study looked at cognitive control in meth users who were separated into groups by length of time drug-free and years using the drug. Recent recovering addicts (three weeks to six months) performed significantly poorer on impulse control tests than subjects who had been clean for a year or longer.

Most encouraging, researchers found no difference in brain function in tests for meth addicts who had abstained for at least a year compared with a control group of non-users.

The behavioral study confirms results from UC Davis functional magnetic resonance imaging, or MRI, research in 2005 showing partial "normalization" of neurochemicals in some brain regions after a year of meth abstinence.

"It does now appear that, prior to a year, there doesn't seem to be much recovery from methamphetamine," Salo says. "Addiction is the ultimate breakdown of impulse control, and it takes time for people to get that decision-making back."

The one-year timetable for brain normalization conflicts with standard 90-day meth treatment programs.

David Husid, project director at Quinn Cottages transitional housing in midtown Sacramento and a former meth addict himself, says the UC Davis study confirms what drug counselors have long told those in recovery.

"Narcotics Anonymous has always used this magic number – one year. Just give it a year," Husid says. "We always asked, why a year? It's great to see this study basically showing with facts that a year is what it takes."

The problem, Husid says, is making it through the year of abstinence to feel an easing of the cravings.

"Everything's times 10 on meth," Husid says. "It starts to take over what your brain normally does for you. When you stop using, you get that flat effect where nothing gives you the same sensation. Normal things that used to make you feel good don't. So you constantly have the urge to go back to chasing that high."

Even the best intentions, Husid says, are overridden by chemical craving. He speaks from experience: He says he went through several failed rehab stints before finally getting clean 10 years ago.

"The longer you're in treatment, the better chance you have," Husid says. "If you're doing outpatient treatment, it's that home environment that throws you off. But if you're in somewhat of a bubble in a program, accountable to someone other than yourself, the chances of you getting to that one-year mark (are higher).

"When most people get out of treatment, within the first 90 days, it's really difficult to keep from relapsing. Your decision-making abilities aren't there. You're still into that immediate satisfaction of getting high."

He sees the UC Davis study as a tool to encourage users to hold out and hang on.

"Most people use meth as an excuse to throw it all away. They'll say, 'My brain's shot anyway. Might as well use. I'll never be normal again.' Well, that's not true."