WEDNESDAY, Sept. 8 (HealthDay News) -- Repeat impaired-driving offenders have subtle deficits in their decision-making abilities that may not be detected through conventional tests, says a new study.

Researchers assessed 34 male, second-time DUI (driving under the influence) offenders enrolled in a rehabilitation program and a control group of 31 healthy, non-offenders matched for age, education, and alcohol use.

All the participants underwent psychiatric assessments ad conventional neuropsychological testing, including the the Iowa Gambling Task (IGT), to help assess personality patterns.

The IGT, Kasar explained, is used in many studies investigating alcohol problems because it simulates real-life decision-making.

"We found that second-time DUI offenders have a poorer performance on the IGT test than their matched counterparts," Muzaffer Kasar, a resident in psychiatry at the Bakirkoy Research and Training Hospital in Istanbul, Turkey, said in a journal news release.

In contrast, he and colleague David J. Nutt, a professor of psychiatry at Imperial College London in the U.K., found no differences between the repeat DUI offenders and the control group on conventional neuropsychological testing and temperament and character testing (TCI) scores.

"These findings suggest that second-time DUI offenders do not suffer from motor impulsiveness -- that is, a lack of impulse control in 'here and now' situations," Nutt said. Instead, he explained, "they suffer from cognitive impulsiveness, which depends on associating negative experiences with possible negative consequences."

In other words, "there are brain reasons for why people make poor choices regarding DUI," he added.

The researchers urged that such testing be expanded for people convicted of DUI, which they noted accounted for 40 percent of the fatal motor vehicle crashes in the United States. In addition, they said, 33 percent of the DUI drivers were recidivists, or repeat offenders.

The study appears online and in the December print issue of the journal Alcoholism: Clinical & Experimental Research.

More information

The U.S. Centers for Disease Control and Prevention has more about impaired driving.