Abstract/Summary

Previous research in healthy young and older adults has reported significant improvements in several cognitive domains (executive function, processing speed, attention) following acute and chronic supplementation of anthocyanin-rich treatments. Most recently, research has started to examine whether similar anthocyanin-rich interventions can benefit children’s cognition. To date, research has demonstrated significant improvements to episodic memory and executive functions following a single, one-off dose (acute) of a 30 g freeze-dried wild blueberry (WBB) beverage (253 mg anthocyanins) in healthy seven to tenyear-old children. This thesis aimed to extend the previous research in three ways. First, by investigating the effects of a daily dose of WBB consumed over four weeks (chronic) on children’s cognition, in addition to the acute effects of WBB consumption. Second, by examining whether acute and chronic WBB supplementation exerted additional benefits to reading behaviour, and mood. Third, by examining whether acute WBB effects on performance differed as a result of time of day: morning versus afternoon testing. The cognitive, reading behaviour, and mood, effects of a freeze-dried WBB powder beverage (253 mg anthocyanins) were investigated in four placebo-controlled, betweensubjects experiments; treatments groups matched for age and gender. Acute effects of WBB supplementation were examined in three studies (Study 1: N = 54, Study 2: N = 61, Study 4: N = 40); the fourth explored both acute and chronic WBB effects (Study 3: N = 30). Consistent improvements to executive function (faster reaction times), as assessed by the Modified Attention Network Task, were demonstrated in response to both acute and chronic WBB relative to placebo. More specifically, these effects were demonstrated under conditions of high cognitive demand, for example, during faster executive function trials and during afternoon testing where children perform below their cognitive optimum. Acute WBB intake improved total word recall and delayed word recall on a list-wise word learning task (Rey’s Auditory Verbal Learning Task) relative to placebo. Self-reported positive affect (Positive Affect and Negative Affect Scale for Children) improved following acute WBB consumption relative to placebo, whilst chronic WBB consumption maintained both positive affect and negative affect. In this instance, acute and chronic WBB supplementation did not benefit word reading (Test of Word Reading Efficiency) or learning to read words (orthographic learning task). ii This research supports previous studies demonstrating WBB-related improvements on children’s cognition and is the first to demonstrate acute WBB effects on mood, and chronic WBB effects on cognition and mood, in children. As reading is a cognitively demanding task, it was hypothesised that WBB-related effects might be further observed for reading; however this hypothesis was not supported. One explanation is that all children recruited had average to good reading ability. Therefore, this highlights whether WBB supplementation would benefit reading behaviour in this cohort of children. Instead, future research should consider whether WBB supplementation can improve reading behaviour in poor performers and those with a deficient habitual flavonoid intake.