Depression, personality, and gender influence EEG, cortisol, beta-endorphin, heart rate, and subjective responses to smoking multiple cigarettes

Abstract

EEG, hormonal, and subjective effects of smoking multiple cigarettes were assessed in 8 males and 8 females who smoked their own habitual brand of cigarette on one occasion, a nicotine-free control cigarette via a quantified smoke delivery system (QSDS) on another occasion, and standard cigarettes by means of a QSDS on two other occasions. Smoking nicotine-containing cigarettes decreased drowsiness and delta and theta EEG magnitude while it increased serum cortisol. Nicotine enhanced beta2 magnitude significantly more in the right than left hemisphere. Nicotine-induced changes in serum cortisol, drowsiness, and EEG magnitude correlated with each other, such that increases in cortisol correlated with increased arousal. Prior to smoking, nicotine-deprived female smokers displayed more drowsiness and delta and theta EEG activity than males and female nonsmokers, but did not differ in this regard after smoking. Female smokers also reported more trait depression than other participants. Extraversion correlated positively with nicotine-induced decreases in drowsiness, theta, and alpha EEG magnitudes, while neuroticism and depression correlated negatively with these changes. BDI depression score correlated with greater nicotine-free baseline EEG activation of the right than left hemisphere. Nicotine tended to eliminate (normalize) this frontal EEG asymmetry that is characteristic of depressed individuals.