This single-blind, placebo controlled study reports on the effects of administering three acute doses of nicotine (0.4, 0.6 and 0.8 mg) subcutaneously to a group of Alzheimer's disease (DAT) patients (n = 22), young adult controls (n = 24), and normal aged controls (n = 24). The study extends our previous findings obtained using smaller groups of subjects. Drug effects were examined on three computerised tests: the first measuring rapid visual information processing, sustained visual attention and reaction time (RVIP task); a delayed response matching to location-order task measuring sustained visual attention and visual short-term memory (DRMLO task); and a finger tapping test measuring simple reaction time (FT task). The critical flicker fusion test (CFF) was used as a measure of perception and the WAIS digit span forwards (DS), of auditory short-term memory. Tests were graded in difficulty, titrated to avoid floor and ceiling effects so that meaningful, direct comparisons between groups could be made. Nicotine significantly improved sustained visual attention (in both RVIP and DRMLO tasks), reaction time (in both FT and RVIP tasks), and perception (CFF task--both ascending and descending thresholds). Nicotine administration did not improve auditory and visual short-term memory. There were no consistent, overall patterns of difference in performance between smokers and non-smokers in the control groups, or between males and females in any group. Despite the absence of change in memory functioning, these results demonstrate that DAT patients have significant perceptual and visual attentional deficits which are improved by nicotine administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Nicotine in patients with dementia of the Alzheimer type (DAT) produced a significant and marked improvement in discriminative sensitivity and reaction times on a computerised test of attention and information processing. Nicotine also improved the ability of DAT patients to detect a flickering light in a critical flicker fusion test. These results suggest that nicotine may be acting on cortical mechanisms involved in visual perception and attention, and support the hypothesis that acetylcholine transmission modulates vigilance and discrimination. Nicotine may therefore be of some value in treating deficits in attention and information processing in DAT patients.

In the first experiment, after a 10-min baseline test on a rapid information processing task, subjects received oral doses of either placebo, methscopolamine 1.2 mg, scopolamine 0.6 mg or scopolamine 1.2 mg, and 1 h later performed the task again for a 20-min period. Following scopolamine 1.2 mg, correct detections were significantly lower over the 20-min period, whereas no such decrement was observed in the other three conditions. In the second experiment a similar design was used to study the effects of nicotine 0.5 mg, 1.0 mg and 1.5 mg and placebo, except that post-drug testing was carried out 10 min after baseline due to the faster absorption of nicotine. Nicotine helped prevent both the decline in detections and the increase in reaction time which occurred over time in the placebo condition. These findings indicate that compounds with opposite effects on central cholinergic pathways produce opposite effects on the performance of a task involving rapid information processing, and are consistent with previous findings from this laboratory.

In this paper two experiments are reported which were designed to investigate the effects of smoking on the performance of a rapid information processing task. The task involves the detection of sequences of three consecutive digits of the same parity from a series of digits presented visually at the rate of 100/min. In the first experiment smoking improved both the speed and accuracy of performance above rested baseline levels, the greatest improvement occurring with the highest nicotine and tar delivery cigarette. In the second experiment smoking again improved the speed and accuracy of performance above baseline levels, while performance deteriorated over time after not smoking as well as after smoking a nicotine-free cigarette. These findings demonstrate that smoking produces absolute improvements in performance and are explained in terms of the action of nicotine on central cholinergic pathways.

The objective of this study was to evaluate the effects of low doses (75 mg and 150 mg) of caffeine on mood and cognition in healthy people, with minimal abstinence of 1 h from caffeine. Improvements were obtained in cognition for attention, problem solving and delayed recall, but not immediate recall or working memory, but performance in the placebo condition was close to the maximum, giving little margin for improvement. For mood, there were statistically significant increase in clearheadedness, happiness and calmness and decreases in tenseness. These mood and performance-enhancing effects of caffeine cannot be seen as representing an alleviation of deficits induced by caffeine abstinence, because there was only minimal deprivation from caffeine.