Mixed Nuts and Brain Vascular Function

Study Overview
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Brief Summary
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Impaired brain vascular function precedes the development of reduced cognitive performance, while brain insulin-resistance is also associated with cognitive decline. The Mediterranean diet, which is rich in nuts, may protect against the development of impaired cognitive performance. The hypothesis is that long-term mixed nut consumption increases brain insulin-sensitivity thereby improving brain vascular function and cognitive performance. The primary objective is to evaluate in elderly men and women the effect of 16-week mixed nut consumption on cerebral blood flow, as quantified by the non-invasive gold standard magnetic resonance imaging (MRI)-perfusion method Arterial Spin Labelling (ASL). Cerebral blood flow is a robust and sensitive physiological marker of brain vascular function. Secondary objectives are to investigate effects on the cerebral blood flow response to intranasal insulin delivery - a marker of insulin-sensitivity in the human brain - as quantified by ASL, and cognitive functioning as assessed with a neuropsychological test battery.

Official Title
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The Long-Term Effects of Mixed Nuts Consumption on Brain Vascular Function in Elderly Men and Women

Conditions
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Brain Vascular Function, Cerebral Blood Flow

Intervention / Treatment
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* Dietary Supplement: Mixed Nuts


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Aged between 60-70 years BMI between 25-35 kg/m2 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 evidenced during the screening visit Exclusion Criteria: Allergy or intolerance to nuts 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)

Ages Eligible for Study
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Minimum Age: 60 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Crossover Assignment Participants will receive, in random order, daily 60 g of mixed nuts (mixed nut treatment) or no food products (control treatment) for sixteen weeks, separated by a washout period of at least 8 weeks.
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Experimental<br>Mixed nuts | Dietary Supplement: Mixed Nuts<br>* Study volunteers will receive daily 60 g of mixed nuts (15 g walnut, 15 g cashew, 15 g hazelnut, 15 g pistachio) for 16 weeks.<br>|
| No Intervention: Control<br>No mixed nuts | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Brain Vascular Function | Cerebral blood flow as quantified non-invasively by the MRI perfusion method Arterial Spin Labeling (ASL) | Change in outcomes at the end of a 16-week mixed nuts intervention and 16-week control period. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Brain Insulin Sensitivity | Change in cerebral blood flow, as quantified non-invasively by the MRI perfusion method Arterial Spin Labeling (ASL), before and after application of intranasal insulin (160 IU) | Change in outcomes at the end of a 16-week mixed nuts intervention and 16-week control period. | 
| Cognitive performance | Cambridge Neuropsychological Test Automated Battery (CANTAB) | Change in outcomes at the end of a 16-week mixed nuts intervention and 16-week control period. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Brain Insulin Sensitivity, Cognitive Performance