In interviews with 700 adults with a drunk-driving conviction, researchers found nearly half had either been drinking heavily for the long haul, or had fallen back into heavy drinking after trying to cut down for a time.

What's more, between one-fifth and one-third of those chronically risky drinkers met the definitions for alcohol or drug dependence, or for mental health conditions like depression and post-traumatic stress disorder.

"A DWI conviction identifies people at risk," said study leader Dr. Sandra C. Lapham, of the Behavioral Health Research Center of the Southwest in Albuquerque, New Mexico.

"It's a red flag," she said in an interview, "and it's an opportunity to intervene."

DWI stands for "driving while intoxicated." Some U.S. states use the term DUI, for "driving under the influence."

Usually, courts mandate DWI offenders be screened for alcohol or drug dependence.

But, Lapham noted, people have to pay for that screening themselves. And even if they are screened, they may be "motivated to underestimate" their drinking levels, Lapham said.

Some DWI offenders with drinking problems may not believe anything is wrong. Others may want help, but can't pay for treatment, Lapham said.

"This all leads to undertreatment," she said.

Her team's findings, which appear in the journal Addiction, are based on interviews with 696 New Mexico adults who'd been convicted of DWI about 15 years earlier.

Lapham's team asked them about their lifetime drinking patterns. Women were considered "risky" drinkers if they habitually had more than seven drinks per week or four or more on any given day. For men, the limits were more than 14 drinks per week or five or more drinks in day.

Overall, 13 percent of the participants had varying drinking patterns throughout their lives. Another 14 percent said they had managed to cut down from heavy drinking to more-moderate levels and keep it that way.

And 21 percent said they'd become abstinent, after some period of risky drinking.

But nearly half of the group had ongoing struggles. Nineteen percent of participants reported a "lifetime" of risky drinking and one-quarter said they'd gone back to risky drinking after trying to quit or cut back.

And those people, the study found, had high rates of alcohol or drug dependence as well as other mental health disorders like depression.

Of people who had tried to cut back on drinking but failed, for example, one-third had been dependent on drugs at some point in their lives. And 30 percent had suffered some other mental health disorder.

These are people who need "intensive treatment," Lapham said.

And getting them into that treatment at the time of a DWI conviction could have the bonus of protecting other drivers and pedestrians, according to Lapham.

That's because people convicted of DWI have a high risk of repeat offenses, she said.

Of course, that requires people to be willing to undergo treatment, and for someone to pay for it. Insurance may cover substance abuse treatment, but not necessarily for the length of time a person needs, Lapham noted.

"It's a difficult problem with no easy answer," she said. But in her opinion, society should foot the treatment bill -- "because we, as a society, would benefit from it," Lapham said.

The researchers did not specifically ask people about the period immediately following a DWI conviction to see if arrests had any effect on their drinking behavior.

One other finding that did come out of the study was that DWI offenders who'd started drinking early in life were at particular risk.

Nearly three-quarters of people who'd started drinking heavily before age 15 became alcohol-dependent at some point. And they were only half as likely as other drinkers to eventually quit or cut down to moderate levels.

"I think parents should be aware of that," Lapham said. If they can keep their kids from drinking at an early age, she said, that might save them from years of problems ahead.

SOURCE: bit.ly/KnqktC Addiction, online June 8, 2012.

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