Investigate the Effect of Tart Montmorency Cherry Juice (Prunus Cerasus) on Cerebral Blood Flow and Cognitive Function

Each participant will be required to attend the laboratory on three occasions. The first of these will be an initial screening/training visit, within 14 days of the first active study visit. During the initial visit participants will be provided with written informed consent and screened with regards the study exclusion/inclusion criteria. Training will be given on the cognitive tasks and familiarisation with the study procedures will be provided.

Study days: Forty - eight hours prior to each study day, participants will begin dietary restrictions. Participants will then attend the first study day following an overnight fast. A cannula will be inserted and baseline blood samples obtained, baseline measures of cerebral blood flow will be examined using near infrared spectroscopy and its effect on cognitive function using a cognitive demand battery. The relevant drink will then be provided and blood samples and blood flow measures will be taken at hourly intervals (1, 2, 3, and 5h). No additional food or drink will be provided during the study period except for low-nitrate mineral water. After a minimum of 2 weeks, participants will be asked to return to the lab and repeat the procedure with the other drink.

Cerebrovascular Responses

Cerebral oxygenation will be assessed using near - infrared spectroscopy . Two near-infrared sensors will be placed on the skin over the right and left prefrontal cortex region of the forehead, and the signals were averaged to determine cerebral oxygenation. The sensors will be secured to the skin using double-sided adhesive tape and shielded from ambient light using an elastic bandage. The sensors alternately emit near-infrared light at wavelengths of 730 and 810 nm. Each sensor contains two detectors located at 3 and 4 cm from the emitting source that detect oxygenated and deoxygenated states of Hb to estimate regional O2 saturation based on internal algorithms (Rasmussen et al. 2007).

Blood velocity in the middle cerebral artery (MCAV) will be determined using transcranial Doppler sonography. A 2 MHz Doppler probe was positioned over the right middle cerebral artery using previously described search techniques (Aaslid et al. 1982) and will be secured with an adjustable headset (DiaMon, Compumedics DWL). The mean depth for Doppler signals was 51 ± 3 mm. Arterial blood pressure will be recorded with a transducer located at heart level (TruWave, Edwards Lifesciences, Nyon, Switzerland).