Overview

Impaired brain vascular function precedes the development of reduced cognitive performance, while brain insulin-resistance is associated with cognitive decline. Evidence from epidemiological studies has already suggested beneficial effects of wild blueberry consumption on cognitive performance. However, underlying mechanisms have not yet been established, while well-controlled trials on longer-term effects of wild blueberries on cognitive performance are highly needed. This study hypothesizes that longer-term wild blueberry intake improves (regional) brain vascular function and insulin-sensitivity, thereby improving cognitive performance in older men and women. The primary objectives are to investigate in older adults the effect wild blueberry consumption on (regional) vascular function and insulin-sensitivity in the brain, and to focus on changes in cognitive performance as assessed with the CANTAB neuropsychological test battery (i.e., secondary objective). Cerebral blood flow responses before (brain vascular function) and after the administration of intranasal insulin spray (brain insulin-sensitivity) will be non-invasively quantified by the non-invasive gold standard magnetic resonance imaging (MRI)- perfusion method Arterial Spin Labeling (ASL).

Eligibility

Inclusion Criteria:

• Men and women, aged between 60-75 years
• BMI between 25-35 kg/m2 (overweight or obese)
• Fasting plasma glucose < 7.0 mmol/L
• Fasting serum total cholesterol < 8.0 mmol/L
• Fasting serum triacylglycerol < 4.5 mmol/L
• Systolic blood pressure < 160 mmHg and diastolic blood pressure < 100 mmHg
• Stable body weight (weight gain or loss < 3 kg in the past three months)
• Willingness to give up being a blood donor from 8 weeks before the start of the study, during the study and for 4 weeks after completion of the study.
• No difficult venipuncture as evidences during the screening visit.

Exclusion Criteria:

• Allergy or intolerance to berries
• Left-handedness
• Current smoker, or smoking cessation < 12 months
• Diabetic patients
• Familial hypercholesterolemia
• Abuse of drugs
• More than 3 alcoholic consumptions per day
• Use of products or dietary supplements known to interfere with the main outcomes as judged by the principal investigators
• Use medication to treat blood pressure, lipid, or glucose metabolism
• Use of an investigational product within another biomedical intervention trial within the previous 1-month
• Severe medical conditions that might interfere with the study, such as epilepsy, asthma, kidney failure or renal insufficiency, chronic obstructive pulmonary disease, inflammatory bowel diseases, auto inflammatory diseases, and rheumatoid arthritis.
• Active cardiovascular disease like congestive heart failure or cardiovascular event, such as an acute myocardial infarction or cerebrovascular accident.
• Contra-indications for MRI imaging (e.g., pacemaker, surgical clips/material in body, metal splinter in eye, claustrophobia)