AGING, SMOKING AND HEMISPHERIC EEG ASYMMETRY

As previous research has shown central nicotinic receptors to (a) be a symmetrical, (b) decline with age, and (c) be more abundant in smokers , quantified EEG indices of hemispheric asymmetry were employed to ass ess whether smoker/non-smoker status affected the aging brain and whet her the aging brain demonstrated an altered response to acute smoking/ nicotine. Forty healthy volunteers participated, including 20 young (1 8-39 years) and 20 elderly (64-81 years) adults. Half of the subjects in each age category were lifelong non-smokers and half were cigarette smokers with average smoking histories of 9.3 and 52.0 years for youn g and elderly respectively. Inter-hemispheric theta and alpha asymmetr y indices illustrated greater left hemisphere power (relative to right ) in elderly adults, while the reverse trend was seen in young adults. Smokers and non-smokers both showed similar aging trends but differed with respect to their presence in frontal and posterior regions. Intr a-hemispheric asymmetry indices, particularly with alpha activity, ill ustrated a reduced anterior-posterior gradient of power distribution i n the elderly. Acute smoking increased slow (delta) and fast (beta) in ter-hemispheric indices but only in elderly smokers. Smoking also alte red the intra hemispheric balance of slow wave activity in both age gr oups of smokers. The results are discussed in relation to normal and p athological aging.