Relationship of electroencephalographic and cardiovascular changes to plasma nicotine levels in tobacco smokers

Objective The effects of smoking one tobacco or placebo cigarette on the mean change in voltage of the electroencephalogram (EEG), arterial blood pressure, heart, and eye blink rates were correlated with the increase in plasma nicotine, exhaled carbon monoxide, and carboxyhemoglobin levels. Methods Twenty nonsmokers (age range, 19 to 42 years; mean age ± SE, 27.0 ±1.9 years) and 65 regular tobacco smokers (age range, 20 to 48 years; mean age ± SE, 27.7 ± 0.8 years) were studied about 10 to 12 hours after overnight tobacco deprivation and immediately after inhaling air through a straw or after smoking one of their own brands of cigarettes, respectively. Results An increase of at least 10 ng/ml plasma nicotine was needed to obtain a statistically significant decrease in alpha 1 and an increase in beta EEG activity. An increase of at least 15 ng/ml plasma nicotine was needed to obtain a statistically significant decrease in delta EEG activity. The mean dominant alpha frequency, heart rate, systolic and diastolic blood pressure, exhaled carbon monoxide, and carboxyhemoglobin levels increased significantly with increasing plasma nicotine concentrations. Conclusions Measurement of plasma nicotine levels is especially important to quantify the relationship between tobacco smoking, mean EEG activity, and cardiovascular changes. Nicotine plasma concentrations greater than 10 µg/ml produce consistent and statistically significant changes in brain wave activity. Smaller increments in plasma nicotine produce less consistent EEG changes. Clinical Pharmacology and Therapeutics (1994) 55, 370–377; doi: 10.1038/clpt.1994.44