Smokers were asked about problems they had after they stopped or cut down or when they were unable to smoke cigarettes. Individual DSM-IV nicotine withdrawal symptoms were considered, in addition to the binary form of DSM-IV substance dependence criteria for nicotine withdrawal: 1) Participants were queried as to whether they experienced each of the 8 DSM-IV nicotine withdrawal symptoms: irritable or angry, nervous, restless, trouble concentrating, decreased heart rate, increased appetite, feel down or depressed, and trouble sleeping. 2) DSM-IV substance dependence criteria for nicotine withdrawal were met if individuals endorsed 4 or more of the symptoms, or if the individual reported smoking cigarettes to relieve or avoid withdrawal symptoms.
