Rationale: Subthreshold smokers (who smoke < or =5 cigarettes/day) experience withdrawal symptoms, yet they smoke less than is required to maintain serum nicotine levels.
Objectives: For study 1, our aim was to determine (1) if adult subthreshold smokers report withdrawal symptoms; (2) how they rate symptom severity; (3) the length of their latency to withdrawal symptoms; (4) and the relationship between level of cigarette consumption and latency to withdrawal. The aim of study 2 was to attempt to replicate the results of study 1 in a nationally representative sample and to compare subthreshold and threshold (> or =6 cigarettes/day) smokers.
Methods: Study 1 was conducted through telephone interviews. Study 2 was conducted through secondary analysis of data from the National Youth Tobacco Survey (self-administered in schools).
Results: In study 1, all subjects experienced withdrawal symptoms. The mean number of symptoms was 4.3; mean intensity of each symptom was >6 (1-10 scale). A quarter of the subjects could go for > or =2 days before experiencing withdrawal. More frequent smokers had a shorter latency to withdrawal (r=-0.43, p<0.001, n=36). In study 2, 63% of subthreshold smokers reported feeling at least one withdrawal symptom. Median latency to withdrawal was 168 h for subthreshold and 2 h for threshold smokers. A negative correlation between level of cigarette consumption and latency to withdrawal was observed for both groups.
Conclusions: Although subthreshold smokers experience significant withdrawal symptoms, they can smoke infrequently because symptoms may not appear for one to several days. Consistent with the sensitization-homeostasis theory, low doses of nicotine can suppress withdrawal symptoms over long periods.