The current thesis aimed to investigate the effects of breakfast and snack on children’s cognitive performance. Chapter 1 presents an overview of cognitive development followed by a review of previous literature investigating the effects of breakfast and snack consumption on cognitive performance. An overview of glycaemic index (GI) is then provided and linked to breakfast and snack intake. Chapter 2 set out to investigate the effects of a mid-morning snack on attention and memory in children. The chapter also examines whether there were any systematic variations in cognitive performance following a mid-morning snack as a consequence of the calorific content of breakfast. Children were tested on a battery of cognitive tests 90 minutes following the consumption of an apple, banana or no snack. The results did not reveal any significant effects on any measures. Chapter 3 was the same as Chapter 2, except that attention and memory were assessed at 30 and 60 minutes post-snack rather than 90 minutes and prior breakfast intake (kcal) was changed to a covariate. The results showed a significant decline in performance from 30 to 60 minutes postsnack on a visuospatial task. However, there were no other significant results. The main aim of Chapters 4, 5 and 6 was to investigate the effects of the glycaemic index (GI) of two breakfast cereals on children’s attention and memory. Chapter 4 assessed attention and memory in children at 0, 60 and 120 minutes after the consumption of a high GI breakfast (CoCo Pops), a low GI breakfast (All Bran) or no breakfast. The results revealed a main effect of assessment time and a time x breakfast interaction on Choice Reaction Time although post hocs revealed no further significant differences. Chapter 5 set out to replicate Chapter 4 but adopted a repeated measures design and also examined if there were any differential effects of breakfast depending on the children’s age. The results revealed some contradictory effects of both assessment time and of age. No other effects were found. Chapter 6 was a replication of Chapter 5 with the exception of the test battery. The test battery (CDR) employed in Chapter 6 was different from the battery in the previous chapters (CAMBA) and was considered to be more cognitively demanding and hence more sensitive to the effects of breakfast intake. The result showed some conflicting effects of assessment time and age. The results also showed a significant main effect of breakfast on Secondary Memory with better performance after the low GI cereal and an interaction between breakfast and time on Accuracy of Attention with better performance after the low GI at 180 minutes post-breakfast. In summary, snack was not found to have any significant effects on performance. Breakfast had an effect on two measures in Chapter 6 but other than that there were no effects of breakfast. There were also some mixed findings of assessment time and age.

The aim of this thesis was to identify novel techniques in the assessment of nutritional intervention effects upon cognition. The impact of combining different cognitive and physiological assessments of nutritional interventions was explored in order to establish whether it could provide a more detailed picture of any effects, as well as the mechanisms by which they may occur. This thesis initially used two different technologies, electroencephalography (EEG) and near infrared spectroscopy (NIRS) to assess the cerebro-electrical and haemodynamic impact of cognitive task performance following Ginkgo biloba and a Ginkgo biloba/Panax ginseng combination, in healthy young adults. Following on from this, the effects of two different doses of Ginkgo biloba were investigated on cerebral blood flow and oxygenation parameters during the repeated administration of cognitively demanding tasks. The synergistic effect of two interventions believed to possess disparate effects on cerebral blood flow; caffeine and L-theanine, were then assessed during the performance of a range of cognitive tasks. To evaluate the peripheral as well as the central impact of task performance, a further assessment of (two doses) caffeine was conducted whilst cerebral blood flow and oxygenation parameters were monitored alongside an assessment of metabolism via indirect calorimetry (ICa). In an extension of the methodology, an exercise element was incorporated into the protocol and beetroot juice was administered whilst cerebral blood flow and haemodynamics were monitored during task performance, before, during and after cycling at different exercise intensities. The results of this thesis have identified that the methodologies adopted are capable of detecting changes in cerebral oxygenation as a result of, nutritional challenge; differing doses of the same intervention; the synergistic effect of two different interventions, and during incremental exercise whilst performing cognitive tasks. The concomitant measurement of NIRS and ICa were also shown to be effective in simultaneously determining the somatic and cognitive demands of a task. These findings demonstrate the positive contribution to research of combining technologies and methodologies in the assessment of nutritional interventions and provide valuable information in respect of their use in cognitive research.