Brain Electrical Imaging the Dose-Response Effects of Cigarette Smoking

Abstract

Quantitative regional electroencephalographic (EEG) effects of cigarette smoking were examined within a repeated measures design which assessed, and topographically displayed, changes in power spectral estimates resulting from the smoking of low, medium and high tar/nicotine (T/N) yield cigarettes. Although intercigarette yield comparisons revealed no significant EEG differences between yields, comparison of the effects of smoking each yield with sham smoking indicated the presence of a qualitative dose-response effect whereby increasing T/N yields resulted in a progressive posterior-to-anterior spreading of sigificant relative power changes within both theta and alpha frequency bands. These exploratory findings are discussed in relation to smoking maintenance and working hypotheses are formulated for future testing.

The Cholinergic Basis of the Smoking-Induced EEG Activation Profile

“…These electrocortical changes were more or less widespread across the scalp and, although they vary from several previous reports of asymmetrical effects [39] or anteriorization of effects [6,26], they conform to more recent observations of smoking-induced electrocerebral alterations found in both young and elderly adult smokers [29]. Although this power spectrum profile has been shown to vary slightly with nicotine yield [4,5,28,40], the salient electrical feature of power shifts from slow to fast (alpha and beta) frequencies is remarkably similar to that observed with psychostimulants [41]. These effects were generally dissimilar from the mecamylamine-induced EEG changes which, unlike previous reports [42], slowed EEG as indicated by reductions in both absolute alpha 2 and beta power and increases in relative theta.…”

“…Given the pivotal role of the cholinergic system in electrocortical arousal processes and in motivational theories of smoking behaviour [27], the present study was designed to examine the separate and interacting role of nAChR and mAChR systems in the regulation of smoking-induced EEG activation by administering mecamylamine -an nAChR antagonist, and scopolamine -an mAChR antagonist, separately and in combination, prior to cigarette smoke inhalation. As our previous reports have evidenced variations in smokinginduced EEG profiles as a function of recording region, multiple scalp sites were utilized to assist further in the localization of smoking effects [6,25,28,29]. Given the importance of mood regulation and its relationship to arousal in smoking [30] and the controversy over central vs. sensory effects of nicotine [31,32] in the smoking habit, the study also included self-ratings of mood changes as well as ratings of cigarette acceptability and sensory impact.…”

Quantitative EEG Effects of Nicotine Replacement by Cigarette Smoking¹

“…Alpha frequency increases [5][6][7] and theta power decreases [2,5,6,8,9]. Beta power generally increases [5,6].…”

“…Some groups report increased alpha power [2,8] and some have found decreased alpha power [5,10] or no change [6,9].…”

“…Nicotine replacement with gum has similar effects of those of smoking [3,4]. Similarly, sham smoking (which approximates smoking but which does not deliver nicotine) has minimal effects on EEG [2,5,8]. Finally, one study has shown that smoking cigarettes with minute levels of nicotine has minimal EEG effects, similar to sham smoking [11].…”