Subjective responses to nicotine in smokers may be associated with responses to caffeine and to alcohol.

Sensitivity in responses to one drug may relate to sensitivity to other drugs, suggesting broad individual differences in characteristic responsivity across drugs. Data from two separate studies of smokers were reanalyzed to examine associations between acute subjective and cardiovascular effects of nicotine vs. caffeine and between nicotine vs. alcohol. Typical intakes of cigarettes, alcohol, and caffeine were included as covariates when they were correlated with the responses of interest. Significant associations between nicotine and caffeine were seen for most of the subjective measures and for blood pressure responses. Fewer significant associations were observed between nicotine and alcohol. Responses associated between nicotine and both of the other drugs tended to reflect psychomotor stimulation. These results suggest that smokers who are more responsive to some of nicotine's subjective and blood pressure effects are also more sensitive to the same effects of caffeine and, to a lesser extent, of alcohol.