Investigating the Acute Effects of Flavonoids in Blueberries on Cognitive Function.

A Controlled, Cross-over, Acute Intervention Study Investigating the Cognitive and Neuronal Effects of Flavonoids in Blueberries.

This study was a controlled, cross-over, acute flavonoid intervention trial with younger and older adults. Subjects consumed a blueberry beverage during one visit and a control beverage on another. Cognitive function pre drink was assessed, blood and urine samples were taken as well as blood pressure and a measure of vascular reactivity. These outcome measures were taken at 2 and 5 hours post drink.

It was predicted that the flavonoids in the blueberry drink would lead to improved performance on the cognitive tests and vascular reactivity measure compared to following the control drink. It was thought this could be due to increased vaso-dilation and improving blood flow to the brain which was investigated in an extension to the project where a sample of individuals underwent brain imaging in an MRI scanner pre and post a blueberry and a control drink.

The control drink was matched to the blueberry drink for other bioactive compounds which may have affected cognition, specifically sugars and vitamin C. Volunteers were healthy, not on any medication, without high blood pressure, high cholesterol, high BMI, diabetes or other medical conditions. Older adults were aged 61-75 years and younger adults 18-26 years.

Blood and urine samples will be analysed for flavonoid levels and Brain Derived Neurotrophic Factor, a biomarker of memory and learning, flavonoids may lead to increased BDNF production through the ERK-CREB-BDNF pathway.

Flavonoids may also increase nitric oxide production and improve the flexibility of the blood vessels hence the measure of vascular reactivity using the Digital Volume Pulse machine. This can lead to increased vaso-dilation and blood flow to the brain, therefore an fMRI study was carried out the investigate this using arterial spin labeling following acute blueberry supplementation compared to a control drink.

Inclusion Criteria:

• No medical conditions
• Not taking any medication or supplements (or willing to stop taking supplements for duration of study)
• Not lactose intolerant
• Willing to give blood and urine samples
• Not partaking in frequent vigorous exercise
• Not suffering from or history of depression

Exclusion Criteria:

• On blood pressure medication, taking Aspirin or other blood thinning medication
• BMI > 30
• Cholesterol > 6
• Diabetes or other serious medical condition
• Lactose intolerant
• Any learning difficulty e.g. dyslexia