Depression is associated with impaired cognitive function and, more specifically, impaired executive function
Executive function refers to working memory, problem solving, planning, attention, inhibitory control and other cognitive roles that ultimately influence behaviour.
It is thought that impaired executive function maintains symptoms of depression and that depression further impairs executive function.
Childhood and adolescence are critical times for the development of executive function, making young people particularly susceptible to the long-term cognitive effects of depression.
Flavonoids are a class of polyphenols in foods such as coffee, tea, cocoa and berries. Flavonoids are well documented to improve cognitive function, but there is little research on the effects of flavonoid interventions on mood.
Given the connection between cognition and depression as well as the effects of flavonoids on cognition, researchers at Reading University in the United Kingdom set out to evaluate the acute effects of blueberry flavonoids on mood in children and young adults. The study was published in Nutrients (2017).
The double-blind, placebo-controlled, crossover study involved two separate groups of participants: 21 young adults (aged 18-21 years) and 50 children (aged 7-10 years).
On each of three test visits, participants completed a baseline mood assessment (the Positive and Negative Affect Schedule), drank a flavonoid-rich wild blueberry drink or a placebo, and returned 2 hours later for another mood assessment.
The wild blueberry drink provided 253mg of anthocyanins from freeze-dried blueberries.
In both groups, increased positive affect (the experience of positive moods, such as joy, interest and alertness) was observed 2 hours after consumption of the wild blueberry drink, with a significant drink-by-session interaction. The wild blueberry drink had no effect on negative affect (the experience of negative moods, such as sadness, fear or anger).
The mechanism to explain the effect of blueberries and flavonoids on mood is not known, but the authors of this study conclude that flavonoid-rich foods may be a promising intervention to promote positive mood in children and young adults.