The effects of smoking on electrocortical arousal in coronary prone (type A) and non-coronary prone (type B) subjects

Nicotinic receptors and attention

Facilitation of different attentional functions by nicotinic acetylcholine receptor (nAChR) agonists may be of therapeutic potential in disease conditions such as Alzheimer's disease or schizophrenia. For this reason, the neuronal mechanisms underlying these effects have been the focus of research in humans and in preclinical models. Attention-enhancing effects of the nonselective nAChR agonist nicotine can be observed in human nonsmokers and in laboratory animals, suggesting that benefits go beyond a reversal of withdrawal deficits in smokers. The ultimate aim is to develop compounds acting with greater selectivity than nicotine at a subset of nAChRs, with an effects profile narrowly matching the targeted cognitive deficits and minimizing unwanted effects. To date, compounds tested clinically target the nAChR subtypes most abundant in the brain. To help pinpoint more selectively expressed subtypes critical for attention, studies have aimed at identifying the secondary neurotransmitter systems whose stimulation mediates the attention-enhancing properties of nicotine. Evidence indicates that noradrenaline and glutamate, but not dopamine release, are critical mediators. Thus, attention-enhancing nAChR agents could spare the system central to nicotine dependence. Neuroimaging studies suggest that nAChR agonists act on a variety of brain systems by enhancing activation, reducing activation, and enhancing deactivation by attention tasks. This supports the notion that effects on different attentional functions may be mediated by distinct central mechanisms, consistent with the fact that nAChRs interact with a multitude of brain sites and neurotransmitter systems. The challenge will be to achieve the optimal tone at the right subset of nAChR subtypes to modulate specific attentional functions, employing not just direct agonist properties, but also positive allosteric modulation and low-dose antagonism.

Tobacco smoking produces widespread dominant brain wave alpha frequency increases

The major pharmacological ingredient in tobacco smoke is nicotine, a mild stimulant known to alter brain electrical activity. The objective of this study was to determine if tobacco smoking in humans produces localized or widespread neocortical dominant alpha electroencephalographic (EEG) frequency increases consistent with nicotine stimulation of the brainstem activating system in animals. Twenty-two male volunteer non-deprived tobacco smokers were studied. They were asked not to smoke for at least 1h before the experiment in mid-morning as part of their usual smoking schedule. In the laboratory, they sham smoked and then smoked their favorite tobacco cigarette. Two experimental sessions (#1 and #2) were conducted, separated by a one to two month interval. In both sessions, there were minor statistically significant increases in the dominant alpha frequencies after sham smoking. In both sessions, after the subjects smoked a favorite tobacco cigarette there was a significant generalized increase in dominant alpha EEG frequencies in most scalp recording sites. This study demonstrates that tobacco smoking produces widespread bilateral neocortical increases in dominant alpha EEG frequencies consistent with the stimulant effects of nicotine on the brainstem reticular activating system.

The acute effect of cigarette smoking on pattern visual evoked potentials

Reports of tobacco-induced electrocortical activation and decrements in ocular blood flow in the acute phase indicated that this effect is mediated via nicotine's action or neuronal systems. In this study, pattern visual evoked potentials were investigated in a group of male smokers (22 right eyes of 22 subjects) in separate real smoking and sham smoking sessions. On each session, pattern visual evoked potentials were recorded before smoking, immediately after smoking, and five minutes after smoking. Latency and amplitude values for P100 peaks were assessed and analyzed in each smoking condition for both real smoking and sham smoking sessions. Real smoking significantly decreased P100 latency values (p value related to difference between pre-smoking and immediately after smoking conditions is 0.009) and increased P100 amplitude values (p value related to difference between pre-smoking and fifth minute after smoking is 0.039). Statistically no significant difference was observed in sham smoking sessions. Our results are consistent with smoking-induced stimulant effects on pattern visual evoked potentials.

Transdermal nicotine: single dose effects on mood, EEG, performance, and event-related potentials

A 21-mg dose of nicotine was administered transdermally to 16 overnight smoking-deprived smokers in a double-blind, placebo-controlled design. Mood ratings, electroencephalography (EEG), behavioral performance and event-related potential (ERP: P300) indices of attention and information processing speed were assessed before and 4 h after placebo/nicotine treatment. Although nicotine, relative to placebo, failed to alter mood, it increased absolute and relative power indices of EEG arousal, shortened reaction times, and increased P300 amplitudes. The results are discussed in relation to nicotine's actions on cholinergic transmission and its role in smoking behavior.

Characterization of topographic EEG changes when smoking a cigarette

The acute effects of cigarette smoking on the human electroencephalogram (EEG) were investigated by the topographic mapping technique. Twenty-six subjects participated in this study, which involved sham smoking and real smoking of preferred cigarettes. Effects of smoking were analyzed by statistical and multivariate analysis. Analysis of variance and t-test results showed a significant decrease in the theta and alpha 1 bands but a significant increase in the alpha 2, beta 1, and beta 2 bands. Factor analysis and cluster analysis showed that there were two or three independent regions on the scalp that indicate the effects of smoking on topographic EEG. A hypothesis was formed that smoking has different effects on human EEG profiles for different brain regions and that there are individual variations in the EEG responses to smoking.

Smoking and EEG power spectra: effects of differences in arousal seeking

Reversal theory, a general theory of motivation, emotion and action, has recently been shown to predict lapses in smoking cessation. Individuals are less likely to lapse if they are in the telic (serious-minded, arousal avoidant, goal-oriented) state than when they are in the paratelic (playful, arousal seeking, spontaneous) state. The literature indicates that people can smoke in such a way as to either increase or decrease central nervous system arousal; smoking in the telic and paratelic states might therefore differentially affect the resting electroencephalograph, as quantified by Fast Fourier Transform analysis. The basic hypothesis was supported. Theta power was decreased when subjects in the telic state smoked, while beta 2 power was increased when subjects in the paratelic state smoked; the latter finding was, however, true only for men. The results have important implications for research on changing health behaviors and for smoking cessation programs.

Flexible effects of quantified cigarette-smoke delivery on EEG dimensional complexity

A quantified smoke delivery system (QSDS) was used to experimentally control the administration of inhaled cigarette smoke to 28 male smokers. One puff (2 s, 35 cc) was taken every 30 s on a cigarette (nicotine yield 1.0 mg) until the char line reached 3 mm from the filter wrap. The smoke was inhaled for 5 s. Resting eyes-closed and eyes-open EEG was recorded from F3, F4, P3, and P4 before and after quantified smoke delivery (QSD). EEG dimensional complexity (DCx, a measure derived from chaos theory) was computed using the Takens-Ellner method. QSD appeared to have a 'flexible' effect on EEG DCx, primarily lowering it in subjects whose pre-smoking level was high, not affecting it in subjects whose pre-smoking level was intermediate, and tending to raise it in subjects whose pre-smoking level was low. This replicates previous results obtained with ad libitum smoking, suggesting the hypothesis that smoking may have an "optimizing" effect on the complexity of brain dynamics.

Electroencephalographic effects of cigarette smoking

The effects of cigarette smoking on the electroencephalogram (EEG) of smokers were examined in a study involving both task and no-task conditions. Non-smoking subjects were employed as controls. In light inhaling smokers, (depth of inhalation inferred from pre- to post-smoking changes in tidal breath carbon monoxide), smoking was found to attenuate EEG activity in the delta, theta, and alpha frequency bands, as well as facilitate behavioral performance. For theta, the attenuation was lateralized over the right frontal cerebral hemisphere. In deep inhaling smokers, smoking produced a symmetrical central midline increase in beta2 magnitude, an EEG effect that in the benzodiazepine literature is associated with anxiety relief.

The effects of smoking on the mood, cardiovascular and adrenergic reactivity of heavy and light smokers in a non-stressful environment

Following a period of overnight deprivation, 58 smokers participated in a 90-min laboratory assessment in which they viewed a non-stressful movie and smoked two 0.5-mg nicotine-containing cigarettes. The first cigarette was given to all subjects following 25 min of adaptation and baseline. The next cigarette was provided at their request, which occurred 9-12 min later. "Heavy" and "light" smokers were grouped according to their average morning cotinine values, which fell above or below 250 ng/ml, respectively. The results showed that, relative to their baseline, heavy and light smokers experienced about the same level of post-smoking change in blood nicotine, heart rate and blood pressure. However, heavy smokers showed a significantly greater delta from baseline in post-smoking measures of epinephrine, norepinephrine, tension reduction and increase in vigor enhancement. A strong and consistent correlation was observed between post-smoking increases in epinephrine, tension reduction and increased vigor.

Cardiovascular reactivity and smoking in coronary prone (type A) and non-coronary prone (type B) subjects

Twenty-nine Type A subjects, (greater than 75 percentile on the Jenkins Activity Survey) and 28 Type B's (less than 25 percentile of Jenkins) were asked to smoke 1 cigarette (1.0 mg nicotine, 16 mg tar, 14 mg CO) using a standardized smoking procedure. The results showed that both Type A and B subjects experienced significant smoking induced changes in heart rate, skin temperature and pulse transit time. An analysis of covariance also revealed that the Type A subjects exhibited greater heart rate reactivity due to smoking than their type B counter parts. The results are discussed in terms of the possible role of cardiovascular reactivity in the mediation of the subjective and behavioral effects of smoking in the type A individual.

Effects of cigarette smoking on resting EEG, visual evoked potentials and photic driving

The effects of smoking a cigarette (1.3 mg nicotine delivery) versus sham smoking were studied using EEG, visual evoked potentials (VEP), photic driving (PD) and heart rate (HR) in thirty young healthy male and female habitual cigarette smokers. Heart rate (HR) and exhaled carbon monoxide (CO) level were significantly increased by real as opposed to sham smoking. Real versus sham smoking significantly increased relative power in the beta bands, reduced alpha and theta activity to a small but significant extent, but had no effect on delta activity. Dominant EEG alpha frequency was significantly increased by real as opposed to sham smoking. Smoking produced no significant mean change in PD or VEP. However, correlational analysis indicated that variables such as basal CO level, residual butt filter nicotine, basal electrocortical response level and personality, predicted to varying degrees the magnitude and direction of the effect of smoking on VEP, PD and EEG.