Caffeine and smoking: subjective, performance, and psychophysiological effects.

The effects of caffeine and smoking on cognitive performance, subjective variables, heart rate, and EEG were assessed in two sessions. In one session, subjects received caffeine (2.5 mg/kg bodyweight), while in the other they received placebo. In both sessions they smoked a cigarette (8 cued puffs) having a nicotine yield of 1.2 mg. Caffeine produced an increase in self-reported muscular tension and tended to increase anxiety and delta magnitude. Smoking facilitated performance of a paper-and-pencil math task and increased heart rate. Smoking also appeared to produce cortical activation as indexed by decreased right frontal delta, decreased right centro-parietal theta, globally increased alpha, and increased centro-occipital/decreased posterior-temporal beta 1. Smoking also increased central/decreased posterior-temporal beta 2. Smoking and caffeine did not interact for any measure, suggesting that the epidemiological link between smoking and coffee drinking may have a non-pharmacological basis.