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Biomedical subjects

A Harr

Publications and source records attributed to A Harr.

5 recordsLinked to original sources
PubMed1999

Smoking history and aging-associated cognitive decline: An event-related brain potential study.

Although cigarette smoking has been associated with reduced risk for dementia of the Alzheimer type, relatively little is known about the central impact of a lengthy smoking history, particularly with respect to the cognitive effects, on the normal aging brain. Given that elderly adults have been reported to exhibit poor short-term memory in conditions requiring divided attention, this study utilized behavioral performance and event-related potential (ERP) measures to compare groups (n = 10/group) of young (18-39 years) and elderly (64-81 years) adult smokers and nonsmokers during a continuous visual word recognition task carried out alone and concurrently with an auditory (oddball) tone discrimination task. Young and elderly adult smokers had average smoking histories of 9.3 and 52.0 years, respectively. Significant aging (young > elderly adults) and task (single-task > dual-task) effects were observed for performance accuracy and speed measures as well as for N400/P600 ERP waveform components elicited by 'old/new' word recognition and P300 ERP indices elicited by auditory target detection. The effects of smoking history were limited to the P600 component, which showed faster latencies in elderly smokers than elderly nonsmokers and young nonsmokers. Young smokers exhibited longer latencies than young nonsmokers. The results were discussed in relation to normal and pathological cognition in the elderly.

Adult↗
PubMed1998

The cholinergic basis of the smoking-induced EEG activation profile.

Acute quantitative electroencephalographic effects of cigarette smoking were examined in 15 smokers within a repeated-measures design which assessed changes in power-spectral estimates following acute pre-treatment with placebo, a dose (20 mg) of mecamylamine, a dose (0.6 mg) of scopolamine and a combined dose of mecamylamine and scopolamine. Compared to sham smoking, the smoking of a single cigarette following placebo pre-treatment reduced absolute and relative power in slow (delta, theta) frequency bands, increased absolute and relative power in alpha and beta frequency bands and accelerated mean frequency. These smoking-induced power changes in slow- and fast-frequency bands were differentially affected by the separate and combined actions of the cholinergic antagonists with treatments involving mecamylamine tending to abolish smoking-induced slow-frequency absolute power reductions and fast-frequency relative power increments. Self-ratings of smoking-induced increases in alertness were altered by mecamylamine and combined treatments while sensory aspects of cigarette smoking were only altered with combined mecamylamine and scopolamine pre-treatment. The results are discussed with respect to brain-behaviour relationships and mechanisms maintaining the smoking habit.

Adult↗
PubMed1997

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.

Adult↗
PubMed1996

Assessing the topographic EEG changes associated with aging and acute/long-term effects of smoking.

As neuroelectric research into the smoking/nicotine habit has focused exclusively on young and middle-aged adults, this electroencephalographic (EEG) study was conducted to determine whether a long-term smoking history alters the aging brain and/or whether the aging brain demonstrates an altered sensitivity to acute smoking/nicotine. Forty healthy adults, 20 young, aged 18-39 years, and 20 elderly, aged 64-81 years, volunteered for participation. Half of the young and elderly were nonsmokers with no previous smoking history and the remaining half of the young and elderly were current smokers with average smoking histories of 9.3 and 52.0 years, respectively. Smokers attended the laboratory for two randomized test sessions during which multisite EEG recordings were collected pre and post sham and cigarette smoking. Nonsmokers attended the laboratory for one nonsmoking EEG recording session. Spectral power indices showed aging to be associated with significant reductions in absolute delta and theta power and increases in relative beta power and faster mean total band frequency. Aging effects varied with recording region but not with smoker versus nonsmoker status. Smokers did exhibit a faster mean beta frequency. Acute cigarette smoking decreased absolute delta power in young smokers and increased relative alpha 2, beta power and mean alpha frequency in both young and elderly smokers. Only the young smokers showed increase in mean theta and total frequency. The results are discussed in relation to cognition in normal and pathological aging.

Adult↗