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Biomedical subjects

K Wesnes

Publications and source records attributed to K Wesnes.

At least 55 records · Page 3Linked to original sources
PubMed1990

Early clinical testing of cognition enhancers: prediction of efficacy.

The major problem in predicting clinical efficacy from animal experimental results and phase I data is the lack of resemblance between the models used and the clinical condition. This problem is complicated by the diversity of the potential mechanisms of action of new compounds. A further question is whether Phase I studies should be used as predictors of clinical efficacy at all. Should they be used simply for determining pharmacologically active dose ranges and tolerance? If used as predictors should drug development stop if negative results are obtained? These questions were not resolved. It was nonetheless suggested that some human models (e.g. scopolamine-induced amnesia, hypoxia-induced performance deficits) were indeed potential predictors of clinical response and, in addition, were analogous to similar models in animals. On the other hand characterisation of quantified EEG (QEEG) profiles remained controversial.

Alzheimer Disease↗
PubMed1990

Potential of moclobemide to improve cerebral insufficiency identified using a scopolamine model of aging and dementia.

After a baseline performance assessment, 28 healthy male volunteers received subcutaneous injections of scopolamine hydrobromide to induce deficits in memory, attention and cognitive processes. Subsequent performance testing established the decrements caused by the scopolamine, and then each subject was given one of 3 investigational drugs including moclobemide, or placebo, according to a latin-square design. Parallel versions of the test procedures were used to assess drug effects on the scopolamine-induced cognitive deficits. Whereas marked and statistically significant impairment was identified 60 min after scopolamine injection, the global analysis revealed statistically significant superiority of moclobemide over placebo at 120 min in relieving the scopolamine-induced decrement in performance. These results show that moclobemide may improve cognition in conditions associated with cholinergic deficit. It may therefore be especially indicated in the treatment of cognitive decline occurring with normal aging, depression in elderly people and Alzheimer's disease.

Adult↗
PubMed1989

Effects of temazepam premedication on cognitive recovery following alfentanil-propofol anaesthesia.

The effects of temazepam 20 mg and placebo were compared for premedication in patients anaesthetized with propofol and alfentanil and undergoing day surgery. Temazepam 20 mg significantly reduced preoperative anxiety and increased recovery time. A series of computerized cognitive tasks revealed significant deficits in attention and memory following anaesthesia, which were increased in range and magnitude by temazepam, which were apparent 30 min after surgery and had largely, but not completely, recovered at 4 h. This study has demonstrated that computerized cognitive testing can identify a wider profile of impairments produced by temazepam than has been found in previous work using non-computerized techniques.

Adolescent↗
PubMed1987

Promethazine, scopolamine and cinnarizine: comparative time course of psychological performance effects.

Single oral doses of promethazine (12.5 mg, 25 mg), scopolamine (0.6 mg), and cinnarizine (30 mg), were compared in a double-blind, placebo controlled trial. Twelve normal volunteers undertook a battery of psychological performance tests and a feeling state questionnaire, before drug administration, and at 2-h intervals after. Promethazine and cinnarizine significantly impaired psychomotor performance, information processing and feelings of alertness. With promethazine these reductions were maximal 3-4 h post-drug, with performance returning near to baseline 8-9 h post-drug. With cinnarizine these impairments were maximal 5-6 h post-drug, and performance remained depressed 8-9 h post-drug. Scopolamine significantly reduced feelings of alertness, and memory task performance; the overall performance effects were most evident 1-4 h post-drug.

Adolescent↗
PubMed1986

Facilitation of learning and state dependency with nicotine.

Two studies of nicotine and memory encoding were carried out using a state-dependent design. The first experiment used cigarettes and involved memory for stimuli that could not be encoded phonemically or semantically. The results of this recognition study show that nicotine was facilitating the input of non-phonemicably encodable and non-semanticably encodable information to storage and that nicotine produced state-dependent learning. The second study used nicotine tablets and involved memory for concrete words. The results of the free recall study show that nicotine produced state-dependent learning, that nicotine was facilitating the input of information to storage, but there was no evidence that associative processes had been changed by nicotine. These findings give no support for the suggestion that a cholinergic system in the brain is controlling the encoding of intrinsic cues relating to phonemic and semantic properties of things but not those involving mnemonic encoding by mental imagery, but rather that the cholinergic system is non-specifically involved in encoding.

Association↗
PubMed1986

Effects of temazepam on sleep quality and subsequent mental efficiency under normal sleeping conditions and following delayed sleep onset.

A group of 24 healthy, normal sleepers participated in 2 experiments. The 1st experiment was designed to investigate the effects of 2 nocte doses of temazepam on subjective sleep quality and performance next morning. In contrast to placebo or no-capsule conditions both temazepam 10 and 20 mg improved a number of assessments of sleep quality, although no residual effects on performance were detected. The 2nd experiment was designed to study the effects of temazepam 20 mg on daytime sleeping and subsequent performance following a simulated night shift. Compared to placebo, temazepam had favourable effects on the subjective duration and quality of daytime sleep, but had no overall beneficial or detrimental residual effects on performance.

Adolescent↗
PubMed1985

Smoking as a coping strategy.

People in modern society use an ever increasing variety of psychoactive substances to help them cope with the increasing amount of stress they experience in the course of their lives. A survey was undertaken to investigate the role of smoking as a coping strategy and the relationship between smoking, the other coping strategies available, and personality in an undergraduate student population. There seemed to be three distinct subgroups in this population as defined by their preferred coping strategy: those who seek help from their friends when faced by problems, those who seek "expert advice," and those who attempt to solve their problems alone; often with the use of drugs. Those falling in the third category, that of self-help, were more likely to self-medicate with a wide variety of psychoactive substances. If they were smokers then they smoked more cigarettes and chose their brand on the basis of strength of a cigarette. There was no evidence for different personality types tending to smoke in different situations and no evidence for any link between extraversion or neuroticism and substance use or coping.

Adaptation, Psychological↗
PubMed1985

Evidence of more rapid stimulus evaluation following cigarette smoking.

Experienced male smokers (greater than 15 cigarettes daily) performed a rapid visual information processing (RVIP) task requiring the detection of sequences of three consecutive odd or even digits in a series presented singly on a TV screen, at a rate of 100 digits/minute. Approximately 80 targets occurred every 10 minutes. All subjects took part in three test sessions: (a) Baseline of 10 minutes on the RVIP task, (2) treatment phase of 10 minutes smoking one cigarette (0.9mg or 1.5mg standard machine delivery of nicotine) or not smoking (NS), (3) posttreatment phase of 20 minutes on the task. Before these morning sessions subjects abstained from smoking for at least 12 hours. Smoking increased the number of correct detections and decreased response time compared with pre-smoking baseline and NS sessions. Analysis of vertex Event-Related Potentials to correct detections revealed a significant reduction in P300 latency following smoking compared to NS sessions. It is suggested that smoking has speeded up stimulus evaluation processes in these individuals. These data are consistent with the common self-report by smokers that smoking aids concentration.

Adult↗
PubMed1985

Scopolamine and the sensory conditioning of hallucinations.

By means of a sensory conditioning procedure, auditory 'hallucinations' were produced in a set of subjects by pairing a light and a tone. The effect of two doses of scopolamine on the occurrence of these hallucinations was investigated, and the results showed that they were more likely to occur after scopolamine than when subjects had received a placebo. This change was attributed to the impairment of information processing induced by scopolamine.

Acoustic Stimulation↗
PubMed1984

The effects of cigarettes of varying yield on rapid information processing performance.

The purpose of this study was to determine the effects of four cigarettes having a range of covarying nicotine and "tar" yields on the performance of a rapid information processing task. Twenty five smokers were tested on different days with each of the cigarettes and in a non-smoking control condition. The order of testing was counterbalanced over days using a 5 x 5 Latin Square Design. Not only did smoking help to prevent the decrease in speed and accuracy which occurred over time in the non-smoking conditions, but it actually improved performance over baseline levels. Furthermore, the greatest improvements were found with the higher nicotine yielding cigarettes. These objectively measured effects of the cigarettes on performance matched the subjective evaluations of the effects of the cigarettes outside the laboratory, and are discussed in relation to other questionnaire studies and a survey of smoking at work.

Carbon Monoxide↗
PubMed1984

Effects of scopolamine and nicotine on human rapid information processing performance.

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.

Afferent Pathways↗
PubMed1984

The separate and combined effects of scopolamine and nicotine on human information processing.

Previous work in this and another laboratory has shown that nicotine tablets improve the performance of a rapid information processing task and reduce the Stroop effect, whereas scopolamine has the opposite effects. The purpose of this study was to extend these previous findings by determining whether, when administered together, these two drugs have mutually antagonistic effects on task performance. Two experiments are reported, both using within-subjects double-blind Latin Square designs. In the first, six subjects received single and combined doses of scopolamine 1.2 mg and nicotine 1.5 mg, and there was some evidence that the two drugs had mutually antagonistic effects on the rapid information processing task. In the second experiment 12 subjects received the same doses, but rapid information processing testing was carried out over a longer time period and Stroop testing was introduced at the end of the 2.5 h session. Nicotine was found to counteract the depression of performance produced by scopolamine on both the rapid information task and the Stroop test. These results provide further support for the theory that central cholinergic pathways play a major role in human information processing.

Adolescent↗
PubMed1984

A comparison of temazepam and flurazepam in terms of sleep quality and residual changes in performance.

This study compared the effects of single nightly doses of flurazepam 30 mg and temazepam 40 mg upon both the subjective assessment of sleep quality and performance on 3 tests of mental efficiency 10 h following medication. 12 male and 12 female non-smoker subjects took part, none of whom experienced sleep difficulties. In comparison with their respective placebos, both hypnotics produced marked and significant improvements in the quality, depth and duration of sleep, and reduced the difficulty that the female subjects experienced in getting to sleep. Flurazepam also produced a significant increase in satisfaction with sleep together with significant reductions in the number of awakenings during the night and the level of clearheadedness on waking. The major test of performance was a continuous 20-min rapid visual information processing task. It was found that for both sexes during each of the two consecutive 10-min periods of performance flurazepam produced highly significant residual impairments in both the speed of reaction and the accuracy of detection, while temazepam had no effect. Overall the results indicate that flurazepam produces a wider range of improvements in sleep quality than temazepam at the cost of less clearheadedness on waking and residual impairments in sustained rapid information processing.

Adult↗
PubMed1984

A comparison of temazepam and flurazepam in terms of sleep quality and residual changes in activation and performance.

A study was carried out in order to compare the effects of 40 mg of temazepam (Euhypnos) and 30 mg of flurazepam on sleep experience, and the residual effects on mood and performance of normal volunteers. The effects of the doses were compared with the identical placebos. A sleep experience questionnaire, an activation questionnaire and a rapid information processing test were administered in the morning, 10 h after ingestion. Both drugs produced the same subjective experience. However, large significant, residual effects of flurazepam were seen on activation and performance (correct detections and reaction times) while temazepam had little effect on activation and produced only a small significant residual impairment of reaction times.

Adult↗
PubMed1983

Effects of nicotine on stimulus sensitivity and response bias in a visual vigilance task.

Signal detection analysis was used to examine the effects of nicotine on a visual vigilance task. Groups of light, heavy and non-smokers performed the 80-min task on three separate occasions, and received different doses of nicotine each time. For all three types of smoker, nicotine significantly counteracted the decrement in stimulus sensitivity which occurred over time in the placebo condition, while having no effect on response bias. We argue that nicotine produced this effect by acting on the central, cholinergic pathways controlling electrocortical arousal, and therefore that these pathways play a role in the control of human information processing.

Arousal↗
PubMed1983

Effects of scopolamine on stimulus sensitivity and response bias in a visual vigilance task.

Signal detection analysis was used to examine the effects of scopolamine on a visual vigilance task. A group of non-smokers performed the 60-min task on three separate occasions, receiving a different dose of scopolamine each time. Scopolamine significantly lowered stimulus sensitivity and prevented the rise in response bias which occurred over time in the placebo condition. In a second study methscopolamine was found to have no effect on either stimulus sensitivity or response bias, showing that peripheral cholinergic blockade was not involved in the effects of scopolamine on these measures. It is concluded (1) that in this study central cholinergic blockade disrupted vigilance performance by lowering stimulus sensitivity, and (2) that this finding provides further evidence that central cholinergic pathways are involved in the control of human information processing.

Adolescent↗