(Reuters) - Many people convicted of drunk driving appear to have a lifelong struggle with risky drinking habits, and using their conviction as a way of getting them into treatment could have long-lasting benefits, according to a U.S. study.

In interviews with 700 adults with a drunk-driving conviction, researchers found that 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, according to their report in the journal Addiction.

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 (driving while intoxicated) conviction identifies people at risk, said study leader Sandra Lapham, at the Behavioral health Research Center of the Southwest in Albuquerque, New Mexico.

It's a red flag, and an opportunity to intervene.

Some DWI offenders with drinking problems may not believe anything is wrong. Others may want help, but can't pay for it, she added.

Lapham's team interviewed 696 New Mexico adults who'd been convicted of DWI about 15 years earlier, asking 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 a 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 the group had ongoing struggles. Nineteen percent reported a Lifetime of risky drinking and one-quarter said they'd gone back to risky drinking after trying to quit or cut back.

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

These are people who need intensive treatment, Lapham said - and getting them into treatment at the time of a DWI conviction could have the bonus of protecting other drivers and pedestrians, since DWI offenders have a high risk of repeat offenses.

It's a difficult problem with no easy answer, Lapham added. SOURCE: bit.ly/KnqktC (Reporting from New York by Amy Norton at Reuters Health; editing by Elaine Lies)

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