Abstract/Summary

Wild blueberry (WBB) intervention has previously been demonstrated to have beneficial acute cognitive effects in typically developing (TD) children, however it is unclear whether effects persist chronically. This thesis examined the acute (2 h) and chronic (4 week) effects of WBB (253mg anthocyanins) on the cognition and mood of 7-10 year old children, and aimed to extend behavioural data to elucidate the mechanisms by which effects might occur, using event-related potentials (ERPs) and 24 h urinary metabolite analyses. Initially, acute effects were examined in a TD sample (n=54), where cognition and mood were assessed at baseline and 2 h post-consumption. WBB attenuated forgetting, quickened reaction time (RT) on fast trials, and improved positive affect. Following this, TD children (n=14) completed cognitive and mood measures 2 h following treatment, concurrent with ERP, using a crossover design. Improved accuracy and RT were seen on cognitively demanding incongruent trials following WBB. Remarkably, these effects occurred simultaneously with higher electrophysiological activation in frontal brain areas associated with increased inhibitory function. Mood effects were not replicated. Acute and chronic effects were then investigated in TD children (n=23), and in a sub-sample of children with ADHD (n=10) at baseline, 2 h, 2 weeks and 4 weeks. WBB-related acute improvements included faster RT on fast trials across populations, and attenuated forgetting for children with ADHD. Chronic executive function (EF) benefits persisted on cognitively demanding high load trials in both populations. In a final experiment, chronic WBB-related improvements were seen on cognitively demanding incongruent trials in TD children (n=15). Chronic urinary metabolite analyses indicated specific WBB increases in benzoic, vanillic and ferulic acid derivatives across 4 weeks. Taken together, findings demonstrate cognitive improvements can be seen across acute and chronic WBB intervention in TD children aged 7-10, and preliminarily for those with ADHD. The research also shows 24 h WBB bioavailability in a child cohort for the first time, highlighting metabolites that may cross the blood-brain-barrier and exert cognitive effects. Results add to the evidence that suggests flavonoids may be sensitive to cognitive demand, and novel ERP data implies effects may be mediated by increases in inhibition-related neuronal activation.