reported non-prescription use of sedatives, tranquilizers, painkillers or stimulants or any use of marijuana, cocaine/crack, hallucinogens, inhalants/solvents, heroin or other illicit drugs in the year preceding the Wave 1 interview. Individuals were classified with baseline past-year nicotine or drug dependence if they had met the criteria for DSM-IV dependence on nicotine or any illicit drug in the year preceding the Wave 1 interview, using algorithms comparable to those described above for alcohol dependence.
