Use of other drugs during alcohol-induced blackouts
       Alcohol interacts with several other drugs, many of which are capable of producing amnesia on their own. For instance, diazepam (Valium) and flunitrazepam (Rohypnol) are benzodiazepine sedatives that can produce severe memory impairments at high doses (White et al. 1997; Saum and Inciardia 1997). Similarly, gamma-hyrdoxybutyrate (GHB) is capable of producing amnesia when used alone (Miotto et al., 2001). Alcohol enhances the effects of benzodiazepines and GHB (White et al., 1997). Thus, combining these compounds with alcohol could dramatically increase the likelihood of experiencing memory impairments. Similarly, the combination of alcohol and THC, the primary psychoactive compound in marijuana, produces greater memory impairments than when either drug is given alone (Ciccocioppo et al. 2002). Given that many college students use other drugs in combination with alcohol (O'Malley and Johnston 2002), some of the blackouts reported by students may arise from polysubstance use rather than from alcohol alone. Indeed, based on interviews with 136 heavy-drinking young adults (mean age 22), Hartzler and Fromme (2003b) concluded that en bloc blackouts often arise from the combined use of alcohol and other drugs. In contrast, White and colleagues (in press) observed that, among 50 undergraduate students with a history of blackouts, only 3 students reported doing other drugs during the night of their most recent blackout.  Marijuana was the drug in each case.