WELL; Risks: Weight-Loss Surgery and Alcohol Abuse By NICHOLAS BAKALAR

The most common type of weight-loss surgery may increase the risk for alcohol abuse, a new study says.

Researchers prospectively followed 1,945 bariatric surgery patients, 1,360 of whom had had the Roux-en-Y gastric bypass, while 490 had a laparoscopic adjustable gastric band operation. The rest had other types of surgery. The analysis, published online last week in The Journal of the American Medical Association, assessed alcohol abuse before and after the operations using a well-validated 10-item questionnaire.

Over all, the prevalence of alcohol abuse increased from 7.6 percent before surgery to 9.6 percent after, the researchers found. If the trend were extrapolated nationwide, about 2,000 people might develop alcohol abuse disorders after bariatric surgery each year.

The researchers also found that the popular Roux-en-Y surgery was a strong independent predictor of alcohol abuse; those who had had the procedure were more than twice as likely to abuse alcohol as those who had had the gastric band operation.

The lead author, Wendy C. King, an assistant professor of epidemiology at the University of Pittsburgh, said that the reasons for the findings are unclear. But previous research suggests that after bariatric surgery, patients have higher peak alcohol levels and reach them more quickly.

''Perhaps this change in experience of alcohol contributes to the increase we observed in alcohol use disorder symptoms,'' Dr. King said.