Pathological gambling, classified by the American Psychiatric Association as a disorder of impulse control, has been found to have many similarities to such addictive disorders as alcoholism and drug dependence (Moran, 1970; Lesieur, 1984; Miller, 1980; Wray and Dickerson, 1981; Levison et al., 1983; Rosenthal and Lesieur, 1992). Similarities include an aroused euphoric state comparable to the high derived from cocaine or other drugs, the presence of craving, the development of tolerance (increasingly larger bets or greater risks are needed to satisfy the gambler, or the same bet or win has less effect than before), and the experience of withdrawal-like symptoms when not betting or gambling (Comings et al., 1996). These similarities have caused researchers in search of the origins of pathological gambling to apply relatively new and sophisticated technologies used in other health research, including twin studies, genetics, brain imaging, and other biology-based strategies. Although only a few studies of pathological gambling involve these technologies, several promising avenues of investigation are emerging.

Eisen and colleagues (1997) investigated gambling involvement among 3,359 twin pairs using DSM-III-R criteria, assessed via phone interview. Their original evaluation found that inherited factors explained between 35 and 54 percent of the liability for five individual symptoms of pathological gambling behavior. In addition, familial or genetic factors explained 56 percent of the report of three or more symptoms of pathological gambling, and 62 percent of the diagnosis of pathological gambling (four or more symptoms). This study presented novel evidence that genetic factors have an influence on symptoms of pathological gambling and the development of the disorder.

Winters and Rich (in press) found in a much smaller-scale twin study that, among males, a significant and moderate heritability effect was observed for high-action gambling such as casinos, but not for other types of games. These recent study findings are consistent with that of the earlier classic study of identical twins reared apart by Tellegen (1988); it revealed substantial heri-