The glycaemic effects of single doses of Panax ginseng in young healthy volunteers

The results of two acute placebo-controlled, double-blind cross-over studies assessing the effect of Panax ginseng (G115) on blood glucose levels are reported. In study 1, thirty participants received three treatments: placebo; 200 mg G115; 400 mg G115. In study 2, twenty-seven participants received four treatments: placebo (0 mg ginseng and 30 mg saccharin); ginseng (200 mg ginseng and 30 mg saccharin); placebo–glucose (0 mg ginseng and 25 g oral glucose); ginseng–glucose (200 mg ginseng and 25 g oral glucose). Blood glucose levels were measured at baseline (at 09.00 hours after an overnight fast) and then 60, 90 (study 1 only) and 120 min post-dose. Both studies demonstrated that G115 alone significantly lowers fasting blood glucose levels. Conversely, in study 2 there was a significant drink × ginseng interaction suggesting opposing glycaemic effects of ginseng under fasting and raised blood glucose conditions. These data have implications for the use of ginseng in individuals with poor gluco-regulation

DHA-rich oil modulates the cerebral haemodynamic response to cognitive tasks in healthy young adults: a near IR spectroscopy pilot study

The impact of dietary n-3 PUFA on behavioural outcomes has been widely researched; however, very little attention has been given to their impact on brain functioning in physiological terms. A total of twenty-two healthy adults took part in this double-blind, placebo-controlled study, wherein the cerebral haemodynamic effects of 12 weeks of daily dietary supplementation with either 1 g DHA-rich or 1 g EPA-rich fish oil (FO) or placebo (1 g olive oil) were assessed. Relative changes in the concentration of oxygenated Hb (oxy-Hb) and deoxygenated Hb were assessed in the prefrontal cortex using near IR spectroscopy (NIRS) during the performance of four computerised cognitive tasks. Supplementation with DHA-rich FO, in comparison with placebo, resulted in a significant increase in the concentrations of oxy-Hb and total levels of Hb, indicative of increased cerebral blood flow (CBF), during the cognitive tasks. In comparison, no effect on CBF was observed following supplementation with EPA-rich FO, where concentration changes in the chromophores followed the same pattern as placebo. These encouraging pilot data warrant further application of NIRS in this area

Immunological investigations into synaptic plasticity

Antibody technology was applied to the study of synaptic plasticity resulting from passive avoidance training in the chick and long-term potentiation in the rat. These studies fell into three categories: 1) the disruption of memory for a one-trial passive avoidance task by intracranial injection of an anti-postsynaptic density antiserum 2) mapping time- and locus-specific changes in the chick brain using antisera to the cytoskeletal proteins (Xtubulin and microtubule-associated protein 2 following passive avoidance training and 3) using antibodies to synaptically-enriched antigens to map time- and locus-specific changes in hippocampal subfields following long-term potentiation in the rat. In the first series of experiments an antiserum (RI4) was raised against protein from chick forebrain postsynaptic densities (PSDs). The antiserum was characterised and was found to recognise six distinct antigens as determined by Western Blots. These antigens were found to have a primarily (but not exclusively) synaptic location. Intracranial injections of IgG isolated from R14 resulted in amnesia for a one-trial passive avoidance paradigm in the chick when administered 60min pre-training (but not 30min or 15min pre-training or 1000n post-training), in chicks tested 24hrs (but not Ihr or 3hrs) post-training. In the second set of experiments monoclonal antibodies were used to examine changes in levels of the cytoskeletal proteins a-tubulin and microtubule-associated protein 2 (MAP2) in specific forebrain loci following passive avoidance training in the chick. Of the regions examined, elevations in the titre of anti-a-tubulin were found in the left Intermediate Hyperstriatum Ventrale (IMHV) l hr, 6hrs and 24hrs following passive training, in the left Lobus Parolfactorius (LPO) 1hr following training and in the right LPO 6hrs and 24hrs following training. A hemispherically-asymmetrical change was found in the titre of anti-MAP2 which was interpreted as possibly reflecting a decrease in the amount of the antigen in the left IMHV 24hrs following training. No training-related changes were detected, using either antibody, in a third forebrain region, the Paleostriatum Augmentatum (PA). During the characterisation of antiserum R14 it was found that only one antigen (with an apparent molecular weight of 230kDa) is conserved between the chick and rat brain. The antigen is enriched in synaptic fractions isolated from the rat hippocampus and was used, as well as a PSD-specific monoclonal antibody, 411B, to examine possible changes in hippocampal subfields CAl, CA3 and the dentate area taken at several time-points following tetanisation of the right perforant path. 24hrs following tetanisation (but not at earlier time-points), the titre of R14 was elevated in the dentate area ipsilateral to tetanisation and in both the ipsi- and contralateral CAL The titre of 411B was increased specifically in the target, dentate area and only at 8hrs following tetanisation, an increase which was abolished in the presence of the protein synthesis inhibitor, anisomycin. These results are discussed in the context of current models of synaptic plasticity

Alcohol Hangover and Multitasking: Effects on Mood, Cognitive Performance, Stress Reactivity, and Perceived Effort

The aim of this study was to examine the effects of hangover on mood, multitasking ability, and psychological stress reactivity to cognitive demand. Using a crossover design and semi-naturalistic methodology, 25 participants attended the laboratory in the morning following a night of (i) alcohol abstinence and (ii) alcohol self-administration during a typical night out (with order counterbalanced across participants). They completed a four-module multitasking framework (MTF, a widely used laboratory stressor) and a battery of questionnaires assessing mood, hangover symptom severity, and previous night’s sleep. The effects of the MTF on mood and perceived workload were also assessed. Participants in the hangover condition reported significantly lower alertness and contentment coupled with a higher mental fatigue and anxiety. Multitasking ability was also significantly impaired in the hangover condition. Completion of the cognitive stressor increased reported levels of mental demand, effort, and frustration, and decreased perceived level of performance. MTF completion did not differentially affect mood. Lastly, participants rated their sleep as significantly worse during the night prior to the hangover compared with the control condition. These findings confirm the negative cognitive and mood effects of hangover on mood. They also demonstrate that hangover is associated with greater perceived effort during task performance

Evidence against memorial facilitation and context-dependent memory effects through the chewing of gum

The experiment examined the prediction that chewing gum at learning and/or recall facilitated subsequent word recall. Chewing gum at learning significantly impaired recall, indicating that the chewing of gum has a detrimental impact upon initial word encoding. In addition, a context-dependent memory effect was reported for those participants who both learned and recalled in the absence of gum, however a context dependent effect was not found with chewing gum. The findings contradict previous research

Panax ginseng has no effect on indices of glucose regulation following acute or chronic ingestion in healthy volunteers

In the absence of effective pharmacotherapy for diabetes there has been an increase in the use of, and research into, alternative treatment strategies. These include exercise, dietary interventions and the use of supplements including extracts of ginseng. Two separate, placebo-controlled, double-blind, cross-over studies investigating the effects of chronic ingestion of Panax ginseng (study 1 used G115, study 2 used Cheong Kwan Jang) on glycated Hb (HbA1c; study 1, n 18; study 2, n 11), fasting plasma insulin (study 1, n 17; study 2, n 12), fasting plasma glucose and postprandial response (following breakfast) (study 1, n 23; study 2, n 14) in healthy volunteers are reported. In both studies it was found that Panax ginseng had no effect on any gluco-regulatory parameter investigated. These results are not consistent with those reported for a diabetic sample (albeit using slightly different outcomes). These results would suggest that chronic use of Panax ginseng by non-diabetic individuals will have little long-term effect on glucose regulation. The benefits to glucose regulation associated with long-term ginseng use may only be present in populations with compromised glucose control; however, further research is needed to confirm such a speculation

Gastrointestinal microbiota, diet and brain functioning

A growing interest for research in the relationship between the gastrointestine (GI), GI microbiota, health and disease is due to the potential for research identifying interventio

Neurocognitive and gluco-regulatory effects of Panax ginseng

Complementary and Alternative Medicine (CAM) has long been used in the Far East to aid in the recovery and prevention of illness. Ginseng, an over-the-counter herbal product in the UK, is amongst these herbal CAMs currently available to the general public. Ginseng is renowned for its rejuvenating properties and its purported ability to aid cognitive function and well-being. Despite the huge global market for ginseng there is little in the way of human research, utilising standardised ginseng extracts and well controlled methodology to support many of these claims. Additionally, ginseng's underlying mechanisms of action are poorly understood. The present thesis documents 5 double-blind, placebo-controlled, cross-over trials investigating the effects of Panax ginseng, following acute and chronic ingestion, on behaviour, mood and indices of glucose regulation in young healthy volunteers. The results of the five studies making this thesis suggest that both acute and chronic dosing with Panax ginseng is capable of modulating mood and cognitive performance in healthy young volunteers. Chapters 2 and 3 also demonstrate, for the first time, Panax ginseng's ability to modulate blood glucose levels following a single acute dose in overnight fasted healthy volunteers. In chapters 2 and 3, significant reductions in blood glucose levels and concomitant improvements in mental arithmetic (working memory) performance were reported. Chapter 4 revealed for the first time Panax ginseng's positive effects on traditional measures of working memory, thus posing the suggestion that previous failures to report working memory effects (using traditional working memory tasks) may have been due to poor task selection. Chapter 5 revealed an unexpected superimposed relationship between chronic and acute ingestion of Panax ginseng. The pattern of results suggests that following chronic dosing, an acute dose can further modulate cognition and mood (suggestive of a psychological dependence). The final chapter documents a different profile of cognitive and mood effects following a non-standardised Panax ginseng extract, thus highlighting the need for caution when generalising results across ginseng types and beyond the specific parameters of the methodologies utilised in any given study. Methodological differences between studies may go some way in explaining the inconsistent data patterns reported between studies, research groups and ginseng extracts. These data further highlight the need for well-controlled studies utilising standardised ginseng extracts and the need for the integration of 'theory driven' research in order to fractionate any behavioural effect. Such methodologies will inevitably lead to greater consistency between behavioural studies, at least in the first instance within the restricted population of volunteers utilised in the present thesis.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Energy drinks mixed with alcohol: Are there any risks?

There have now been a number of publications, including laboratory studies and surveys, on alcohol mixed with energy drinks. Some authors have highlighted problems associated with consumption of this beverage combination, including reduced perception of alcohol intoxication and greater alcohol consumption with more negative consequences as a result. For example, the recent article by Marczinski and Fillmore entitled “Energy drinks mixed with alcohol: what are the risks?” suggests that “consuming alcohol mixed with energy drinks is riskier than consuming alcohol alone and constitutes a public health concern.”1 While some publications conclude that consumption of energy drinks mixed with alcohol is problematic, others do not support these claims and point out the methodological shortcomings of many studies in this area

Chewing gum and context-dependent memory: The independent roles of chewing gum and mint flavour

Two experiments independently investigated the basis of the chewing-gum induced context-dependent memory effect (Baker et al, 2004). At learning and/or recall participants either chewed flavourless gum (Experiment 1) or received mint-flavoured strips (Experiment 2). No context dependent memory effect was found with either flavourless gum or mint-flavoured strips, indicating that independently the contexts were insufficiently salient to induce the effect. This is found despite participants’ subjective ratings indicating a perceived change in state following administration of flavourless gum or mint-flavoured strips. Additionally, some preliminary evidence for a non-additive facilitative effect of receiving gum or flavour at either learning and/or recall is reported. The findings raise further concerns regarding the robustness of the previously reported context-dependent memory effect with chewing gum