In terms of prevalence rates of nicotine withdrawal symptoms, our study is mostly consistent with others which found similar rates across gender (Breslau et al., 1992) and age (CDC, 1994). In our analyses, however, there was evidence of heterogeneity for a few specific items. Adult smokers were more likely to report restlessness and less likely nervousness compared to the adolescent smokers; female smokers had higher rates of depressed mood associated with nicotine abstinence compared to male smokers; and among the adolescent smokers, girls reported more irritability and hunger and boys more sleep-related problems. The finding of higher rates of depressed mood in female versus male adolescent smokers extends the findings that we previously reported in the adult sample (Pergadia et al., 2006b). Despite the increased probability of heavy smoking in adults, particularly men, (women: 33%, men: 47%) compared with adolescents (girls: 31%, boys: 29%), only one withdrawal symptom- restlessness- was elevated in the adult smokers over their adolescent counterparts suggesting that many nicotine withdrawal symptoms emerge during nicotine abstinence simply after becoming a smoker (defined here as smoking 100 or
