Researchers say that as many as 30 percent of patients who have had weight loss surgery acquire a new compulsive behavior, the Wall Street Journal reported on July 18.

"Addiction transfer," as some psychologists call it, may have a neurological basis. The biochemical causes of compulsive eating closely resemble those of other impulse-control disorders such as dependence on alcohol, gambling or shopping.

In an effort to find medications that could treat all of these disorders at once, the National Institute on Drug Abuse spent $1.4 million on obesity research last year.

"The potential is extraordinary," said Nora Volkow, NIDA director. "A drug that could condition craving behavior -- whether it's for chocolate or cocaine -- would be a gigantic market."

Several medications currently on the market or under research, including Wellbutrin, Topamax and Rimonabant may be useful in the treatment of substance use disorders as well as obesity, gambling addiction and other disorders.

Research suggests that abnormal dopamine levels in the brain can cause substance misuse and obesity.