Aging, smoking and EEG coherence: a preliminary study.

Although the cigarette smoking habit is prevalent in young, middle aged and elderly adults, it is yet unknown whether a long term smoking history alters the aging brain and/or whether the aging brain demonstrates an altered sensitivity to acute smoking. Inter- and intrahemispheric EEG coherence was compared in 20 young (18-39 years) adults (10 smokers, 10 nonsmokers) and 20 elderly (64-81 years) adults (10 smokers, 10 nonsmokers). The acute effects of sham inhaling on a nonlighted cigarette and cigarette smoking on EEG coherence was also compared in young and elderly adult smokers. In general, elderly adults exhibited reduced interhemispheric coherence values relative to young adults and, depending on the frequency band, age effects varied with recording site. Smokers of both age groups exhibited greater interhemispheric total alpha coherence values than nonsmokers. Similar smoker status effects were found with fast alpha but this varied with recording site. Relative to sham smoking, acute cigarette smoking reduced interhemispheric slow alpha in both young and elderly smokers but reduced total alpha coherence only in elderly smokers. The results are discussed in relation to normal and pathological aging, including dementia.