The acute biobehavioural effects of caffeine in isolation and in combination with other naturally concomitant compounds

Caffeine is often described as the most widely consumed psychoactive drug in the world. Despite a substantial amount of research examining the effects of caffeine on mood and cognition, there remain a number of unresolved issues in this field, two of which formed the focus of this thesis. The first pertains to whether caffeine has any behavioural effects beyond a reversal of withdrawal effects purported to exist in habitual consumers following caffeine deprivation. A second relates to the biobehavioural effects of caffeine when consumed in combination with other potentially psychoactive components, as is usually the case in dietary forms of caffeine. This thesis, therefore, firstly compared the cognitive and mood effects of acute administration of caffeine to habitual consumers and habitual non-consumers of caffeine. The effects of combining caffeine with other naturally concomitant compounds were then explored, firstly by examining the impact of combining caffeine with L¬theanine (an inhibitory amino acid found in tea) and then by exploring the effects of guaranâ (a caffeine-containing whole extract). Finally, following on from these latter studies, an attempt was made to establish the lowest active dose of caffeine. Each experiment followed a placebo-controlled, double-blind, balanced cross-over design. In each study, treatment-related changes in cognitive performance were assessed with computerised assessment tools (the Cognitive Drug Research battery, a sentence verification task and serial subtractions), and mood was assessed using both Bond¬Lader and specifically tailored caffeine research visual analogue scales. Where appropriate, salivary caffeine levels and autonomic activity were monitored. Performance was similarly improved for habitual consumers and habitual non- consumers of caffeine following caffeine administration. The administration of caffeine in combination with L-theanine led to some modulation of the effects of caffeine. This was also demonstrated when examining the effects of guaraná. A direct comparison of caffeine and guaranâ with matched caffeine levels revealed differences in the effects of the two treatments. Exploration of the lowest active dose of caffeine revealed (largely impairing) effects of caffeine at doses lower than those found in decaffeinated beverages. These findings may have important implications for caffeine research. Firstly, they suggest that behavioural effects of caffeine cannot be attributed wholly to withdrawal reversal. Secondly, they demonstrate that other components commonly co- consumed with caffeine are likely to modulate its biobehavioural effects. Finally, they suggest that levels of caffeine hitherto thought to be inactive may have (negative) psychoactive properties

Cognitive and mood improvements following acute supplementation with purple grape juice in healthy young adults

Purpose - Berry-derived phenolic compounds found in grapes have been associated with a number of health benefits, including the augmentation of human brain function and cognition. Previous intervention studies of Concord grape juice have demonstrated improvement to memory and driving ability following 3- to 4-month supplementation in middle-aged and older adults. However, no studies to date have demonstrated acute cognitive benefits of grape juice, and investigation of these effects in young adults is lacking. Methods - This randomised, placebo-controlled, double-blind, counterbalanced-crossover study, assessed the effects of 230 ml purple grape juice or sugar-matched control in 20 healthy young adults. Computerised measures of episodic memory, working memory, attention and mood were completed at baseline and following a 20-min absorption period. Results - Purple grape juice significantly improved reaction time on a composite attention measure (p = 0.047) and increased calm ratings (p = 0.046) when compared to placebo. Order effects also indicated an enduring positive effect on pre-dose memory reaction time (p = 0.018) and post-dose calm ratings (p = 0.019) when purple grape was consumed first. Conclusions - These findings in a small sample of healthy young adults suggest that purple grape juice can acutely enhance aspects of cognition and mood. No significant effects of juice were observed on memory measures, suggesting that these may be less susceptible to manipulation following acute supplementation in healthy young adults. Potential mechanisms underlying these effects include modulation of cerebral blood flow, glucoregulation and inhibition of monoamine oxidase activity, all of which require further exploration

Tart Montmorency cherries (Prunus Cerasus L.) modulate vascular function acutely, in the absence of improvement in cognitive performance

Cerebral blood volume and metabolism of oxygen declines as part of human ageing and this has been previously shown to be related to cognitive decline. There is some evidence to suggest that polyphenol-rich foods can play an important role in delaying the onset or halting the progression of age-related health disorders such as cardiovascular and Alzheimer’s disease, and to improve cognitive function. In the present study, an acute, placebo-controlled, double blinded, cross-over, randomised Latin square design study with a wash-out period of at least 14 days was conducted in twenty-seven middle aged (defined as 45-60 years) volunteers. Participants received either a 60 mL dose of a Montmorency tart cherry concentrate (MC), which contains 68.0 ±0.26 mg cyanidin-3-glucoside /L, 160.75 ± 0.55 mean gallic acid equiv/L and 0.59 ± 0.02 mean Trolox equiv/L, respectively or a placebo (PLA). Cerebrovascular responses, cognitive performance and blood pressure were assessed at baseline and 1, 2, 3 and 5 h following consumption. There were significant differences in concentrations of total and oxy-haemoglobin during the task period 1 h post MC consumption (p ≤ 0.05). Furthermore, MC consumption significantly lowered SBP (p ≤ 0.05) over a period of 3 h, with peak reductions of 6 ± 2 mmHg at 1 h post MC consumption relative to the placebo. Cognitive function and mood were not affected. These results show that a single dose of MC concentrate can modulate certain variables of vascular function; however this does not translate to improvements in cognition or mood

Chewing gum alleviates negative mood and reduces cortisol during acute laboratory psychological stress

The notion that chewing gum may relieve stress was investigated in a controlled setting. A multi-tasking framework which reliably evokes stress and also includes performance measures was used to induce acute stress in the laboratory. Using a randomised crossover design forty participants (mean age 21.98 years) performed on the multi-tasking framework at two intensities (on separate days) both while chewing and not chewing. Order of workload intensity and chewing conditions were counterbalanced. Before and after undergoing the platform participants completed the state portion of the State-Trait Anxiety Inventory, Bond-Lader visual analogue mood scales, a single Stress Visual Analogue Scale and provided saliva samples for cortisol measurement. Baseline measures showed that both levels of the multi-tasking framework were effective in significantly reducing self-rated alertness, calmness and contentment while increasing self-rated stress and state anxiety. Cortisol levels fell during both levels of the stressor during the morning, reflecting the predominance of a.m. diurnal changes, but this effect was reversed in the afternoon which may reflect a measurable stress response. Pre-post stressor changes (Delta) for each measure at baseline were subtracted from Delta scores under chewing and no chewing conditions. During both levels of stress the chewing gum condition was associated with significantly better alertness and reduced state anxiety, stress and salivary cortisol. Overall performance on the framework was also significantly better in the chewing condition. The mechanisms underlying these effects are unknown but may involve improved cerebral blood flow and/or effects secondary to performance improvement during gum chewing

The Acute Effects of Caffeinated Black Coffee on Cognition and Mood in Healthy Young and Older Adults

Cognitive and mood benefits of coffee are often attributed to caffeine. However, emerging evidence indicates behavioural effects of non-caffeine components within coffee, suggesting the potential for direct or synergistic effects of these compounds when consumed with caffeine in regular brewed coffee. The current randomised, placebo-controlled, double-blind, counterbalanced-crossover study compared the effects of regular coffee, decaffeinated coffee, and placebo on measures of cognition and mood. Age and sex effects were explored by comparing responses of older (61–80 years, N = 30) and young (20–34 years, N = 29) males and females. Computerised measures of episodic memory, working memory, attention, and subjective state were completed at baseline and 30 min post-drink. Regular coffee produced the expected effects of decreased reaction time and increased alertness when compared to placebo. When compared to decaffeinated coffee, increased digit vigilance accuracy and decreased tiredness and headache ratings were observed. Decaffeinated coffee also increased alertness when compared to placebo. Higher jittery ratings following regular coffee in young females and older males represented the only interaction of sex and age with treatment. These findings suggest behavioural activity of coffee beyond its caffeine content, raising issues with the use of decaffeinated coffee as a placebo and highlighting the need for further research into its psychoactive effects

Acute and chronic effects of multivitamin/mineral supplementation on objective and subjective energy measures

Background: Vitamins and minerals play an essential role within many cellular processes including energy production and metabolism. Previously, supplementation with a multivitamin/mineral (MVM) for ≥28 days resulted in improvements to cognition and subjective state. We have also demonstrated shifts in metabolism during cognitively demanding tasks following MVM in females, both acutely and following 8-week supplementation. The current study aimed to assess these effects further in males and females using metabolically challenging exercise and cognitive tasks. Methods: The current randomised, placebo-controlled, parallel groups study investigated the effects of a MVM complex in 82 healthy young (18-35y) exercisers. Subjective ratings and substrate metabolism were assessed during 30 min each of increasingly effortful incremental exercise and demanding cognitive tasks. Assessments took place on acute study days following a single dose (Day 1) of MVM, containing 3 times recommended daily allowance of water-soluble vitamins plus CoQ10, and following 4-week supplementation (Day 28). Results: Energy expenditure (EE) was increased during cognitive tasks following MVM across Day 1 and Day 28, with greater effects in males. In males, MVM also increased carbohydrate oxidation and energy expenditure during exercise across Day 1 and Day 28. In females, mental tiredness was lower during exercise; increases in physical tiredness following 30 min of exercise were attenuated; and stress ratings following cognitive tasks were reduced following MVM. In males, MVM only lowered mental tiredness following 10 min of exercise. These effects were apparent irrespective of day, but effects on mental tiredness were greater on Day 28. Ferritin levels were also higher on Day 28 in those receiving MVM. Conclusion: These findings extend on existing knowledge, demonstrating increased carbohydrate oxidation and increased energy expenditure in males following MVM supplementation for the first time. Importantly, they show modulation of energy expenditure and subjective tiredness following a single dose, providing further evidence for acute effects of MVM. Differential effects in men and women suggest that sex may play an important role in the effects of MVM on energy metabolism and should be considered in future research. Trial registration: ClinicalTrials.gov, NCT03003442. Registered 22nd November 2016 – retrospectively registere

Cognitive and mood effects of a nutrient enriched breakfast bar in healthy adults: a randomised, double-blind, placebo-controlled, parallel groups study.

Objectives: Few previous studies have assessed the effects of concomitant administration of multiple potentially psychoactive nutrients. Methods: 95 healthy adult participants consumed either a nutrient enriched breakfast bar (containing α-Linolenic acid, l-tyrosine, l-theanine, vitamins, minerals and 21.5 mg of caffeine) or an isocaloric, macronutrient matched control bar for 56 days. Cognitive function and mood were assessed pre-dose and at 40- and 160-min post-dose on the 1st and 56th day of the intervention period. Results: The results demonstrated acute effects of treatment across post-dose assessments on both assessment days in terms of alertness, and on tasks assessing attention, working and episodic memory and executive function, including cognitively demanding Serial subtraction and Rapid Visual Information Processing tasks. There were no evident chronic effects independent of the breakfast bars’ acute effects. Discussion: These results demonstrate that a nutrient enriched breakfast bar with low caffeine content can exert striking beneficial effects on acute cognitive function and alertness

Complementary Medicine for the Modification of Risk Factors for Cognitive Impairment

There is a natural decline in cognitive function as we age, particularly in processing speed and working memory. A range of modifiable factors can increase the risk of accelerated cognitive decline including hypertension, chronic inflammation, atherosclerosis, diabetes, atrial fibrillation, stroke, and impaired central nervous system glucose regulation. Given the lack of adequate interventions for cognitive decline and dementia, it is essential that treatments with the potential to reduce the risk of cognitive impairment are thoroughly explored

Consumption of cocoa flavanols results in acute improvements in mood and cognitive performance during sustained mental effort

Cocoa flavanols (CF) positively influence physiological processes in ways that suggest their consumption may improve aspects of cognitive function. This study investigated the acute cognitive and subjective effects of CF consumption during sustained mental demand. In this randomized, controlled, double-blinded, balanced, three period crossover trial 30 healthy adults consumed drinks containing 520 mg, 994 mg CF and a matched control, with a three-day washout between drinks. Assessments included the state anxiety inventory and repeated 10-min cycles of a Cognitive Demand Battery comprising of two serial subtraction tasks (Serial Threes and Serial Sevens), a Rapid Visual Information Processing (RVIP) task and a mental fatigue scale, over the course of 1 h. Consumption of both 520 mg and 994 mg CF significantly improved Serial Threes performance. The 994 mg CF beverage significantly speeded RVIP responses but also resulted in more errors during Serial Sevens. Increases in self-reported mental fatigue were significantly attenuated by the consumption of the 520 mg CF beverage only. This is the first report of acute cognitive improvements following CF consumption in healthy adults. While the mechanisms underlying the effects are unknown they may be related to known effects of CF on endothelial function and blood flow

The acute biobehavioural effects of caffeine in isolation and in combination with other naturally concomitant compounds

Caffeine is often described as the most widely consumed psychoactive drug in the world. Despite a substantial amount of research examining the effects of caffeine on mood and cognition, there remain a number of unresolved issues in this field, two of which formed the focus of this thesis. The first pertains to whether caffeine has any behavioural effects beyond a reversal of withdrawal effects purported to exist in habitual consumers following caffeine deprivation. A second relates to the biobehavioural effects of caffeine when consumed in combination with other potentially psychoactive components, as is usually the case in dietary forms of caffeine. This thesis, therefore, firstly compared the cognitive and mood effects of acute administration of caffeine to habitual consumers and habitual non-consumers of caffeine. The effects of combining caffeine with other naturally concomitant compounds were then explored, firstly by examining the impact of combining caffeine with L¬theanine (an inhibitory amino acid found in tea) and then by exploring the effects of guaranâ (a caffeine-containing whole extract). Finally, following on from these latter studies, an attempt was made to establish the lowest active dose of caffeine. Each experiment followed a placebo-controlled, double-blind, balanced cross-over design. In each study, treatment-related changes in cognitive performance were assessed with computerised assessment tools (the Cognitive Drug Research battery, a sentence verification task and serial subtractions), and mood was assessed using both Bond¬Lader and specifically tailored caffeine research visual analogue scales. Where appropriate, salivary caffeine levels and autonomic activity were monitored. Performance was similarly improved for habitual consumers and habitual non- consumers of caffeine following caffeine administration. The administration of caffeine in combination with L-theanine led to some modulation of the effects of caffeine. This was also demonstrated when examining the effects of guaraná. A direct comparison of caffeine and guaranâ with matched caffeine levels revealed differences in the effects of the two treatments. Exploration of the lowest active dose of caffeine revealed (largely impairing) effects of caffeine at doses lower than those found in decaffeinated beverages. These findings may have important implications for caffeine research. Firstly, they suggest that behavioural effects of caffeine cannot be attributed wholly to withdrawal reversal. Secondly, they demonstrate that other components commonly co- consumed with caffeine are likely to modulate its biobehavioural effects. Finally, they suggest that levels of caffeine hitherto thought to be inactive may have (negative) psychoactive properties.EThOS - Electronic Theses Online ServiceGBUnited Kingdo