NCT07422220: WalBrain

Long-Term Effects of Walnut Consumption on Brain Function in Men and Women With Abdominal Obesity

Not yet recruiting NA Last updated 18 February 2026

What this trial tests

NA trial testing Walnuts in Healthy in 55 participants. Not yet recruiting.

Timeline

1 February 2026

Primary endpoint
1 August 2027

1 August 2027

Quick facts

Lead sponsor	Maastricht University Medical Center
Phase	NA
Status	Not yet recruiting
Study type	INTERVENTIONAL
Allocation	randomized
Design	parallel
Masking	triple
Primary purpose	prevention
Enrollment	55
Start date	1 February 2026
Primary completion	1 August 2027
Estimated completion	1 August 2027
Sites	1 location across Netherlands

Drugs / interventions tested

• Walnuts — full drug profile →

Conditions studied

• Healthy — all drugs for Healthy →
• Brain Insulin Sensitivity — all drugs for Brain Insulin Sensitivity →
• Cerebral Blood Flow — all drugs for Cerebral Blood Flow →
• Brain Vascular Function — all drugs for Brain Vascular Function →

Sponsor

Maastricht University Medical Center

Who can join

Adults 45 to 75, any sex, with Healthy or Brain Insulin Sensitivity. Healthy volunteers can join.

What's being measured

Primary outcomes are the specific endpoints the trial is designed to prove or disprove.

• Cerebral blood flow (CBF) prior to and after application of intranasal insulin
  Time frame: From enrollment to the end of treatment at 24 weeks
  CBF will be non-invasively measured using the gold-standard methodology pseudo-continuous arterial spin labeling magnetic resonance imaging (pCASL MRI)

Sponsor's own description

Rationale: Healthy foods, including mixed nuts, may improve brain function, which is essential for cognitive and metabolic health, and may contribute to improved food intake regulation. It is therefore important to investigate the specific effects of walnuts on cerebral blood flow responses before and after intranasal insulin administration, as well as their associated functional benefits. The investigators hypothesize that long-term walnut consumption improves vascular function and insulin-sensitivity in the brain, thereby enhancing cognitive performance and appetite control in abdominally obese men and women. Objective: The primary objectives are to investigate in abdominally obese adults the effects of 24-week walnut consumption on (regional) vascular function and insulin-sensitivity in the brain, while the investigators will also assess changes in cognitive performance and appetite-related brain reward activity (secondary objectives). Cerebral blood flow responses before (brain vascular function) and after the administration of intranasal insulin spray (brain insulin-sensitivity) will be quantified by the non-invasive gold standard magnetic resonance imaging (MRI)-perfusion method Arterial Spin Labeling (ASL). Study design: This intervention study will have a randomized, controlled parallel design. The total study duration will be 24 weeks. Study population: Fifty-five abdominally obese men and (postmenopausal) women (aged 45-75 years) without a history of cardiovascular diseases or complaints will participate. This study population is expected to have a decreased cerebral blood flow at baseline and are also at increased risk of cognitive impairment, allowing for improvement by the intervention. Intervention: Study participants will receive daily 50 g (about 15% of energy) of raw walnuts (walnut intervention) or no walnuts (control intervention) for 24 weeks. Main study parameters/endpoints: At baseline and after 24 weeks (follow-up), participants will visit the research facilities for assessments. The primary endpoint is the difference in the cerebral blood flow response before and after intranasal insulin administration between the walnut and control intervention. Cognitive performance will be assessed, while the investigators will also focus on appetite-related brain reward activity (secondary outcomes).

Publications & conference data

No peer-reviewed publications indexed yet for this trial.