Effects of mecamylamine on spontaneous EEG and performance in smokers and non-smokers.
In a previous study, mecamylamine, a centrally active nicotine antagonist, exacerbated EEG signs of tobacco abstinence in abstinent smokers. In the present study, the effects of mecamylamine were compared in non-smokers and nondeprived smokers. Mecamylamine (0, 5 and 10 mg, p.o.) was administered to six smokers and six non-smokers; eight of these subjects were also given a 20 mg dose. Before drug administration, resting EEG was similar in both groups. In both groups, mecamylamine caused dose-related decreases in alpha frequency and increases in delta frequency; beta frequency was increased by the 5 and 10 mg doses. The similarity of effects in smokers and non-smokers suggests a direct pharmacological action rather than precipitated nicotine withdrawal. Significant baseline differences existed between smokers and non-smokers in systolic blood pressure, pulse rate, skin temperature and pupil diameter. Response time slowed in both vigilance and distractibility tasks and delayed recall was impaired. Mecamylamine increased ratings of: "relaxed," "nodding," "sleepy" and "coasting." This small-sample study tentatively suggests that nicotinic cholinergic mechanisms modulate brain electrical activity and cognitive function in smokers and non-smokers. Disruption of these neural systems could mediate the symptoms of tobacco withdrawal and be involved in the pathophysiology of Alzheimer's disease.
Pickworth
W B
WB
Addiction Research Center, National Institute on Drug Abuse, Baltimore, MD 21224, USA.
Fant
R V
RV
Butschky
M F
MF
Henningfield
J E
JE
D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D003071:Cognition / Q000187:drug effects; D004569:Electroencephalography / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008464:Mecamylamine / Q000494:pharmacology*; D018733:Nicotinic Antagonists / Q000494:pharmacology*; D011597:Psychomotor Performance / Q000187:drug effects*; D011674:Pulse / Q000187:drug effects; D011680:Pupil / Q000187:drug effects; D012881:Skin Temperature / Q000187:drug effects; D012907:Smoking / Q000503:physiopathology*
D018733:Nicotinic Antagonists; D008464:Mecamylamine