Longer-term mixed nut consumption improves brain vascular function and memory: A randomized, controlled crossover...

Area of Science:

• Neuroscience
• Nutrition Science
• Gerontology

Background:

• Age-related cognitive decline is a growing concern.
• The mechanisms by which nut consumption may mitigate cognitive decline are not fully understood.
• Brain vascular function is a potential pathway linking diet and cognition.

Purpose of the Study:

• To examine the long-term effects of mixed nut consumption on brain vascular function in older adults.
• To determine if improved vascular function correlates with cognitive performance changes.
• To investigate the impact of nuts on endothelial function, arterial stiffness, and retinal microvasculature.

Main Methods:

• A randomized, single-blinded, cross-over trial involving 28 healthy older adults (65±3 years).
• Participants consumed 60g/day of mixed nuts (walnuts, pistachios, cashews, hazelnuts) or a control (no nuts) for 16 weeks, with an 8-week washout period.
• Brain vascular function was assessed using arterial spin labeling MRI to measure cerebral blood flow (CBF); endothelial function, arterial stiffness, and retinal microvasculature were also evaluated. Cognitive performance was measured using the Cambridge Neuropsychological Test Automated Battery.

Main Results:

• Mixed nut consumption significantly increased regional CBF in multiple brain areas, including the frontal and parietal lobes.
• Improvements were observed in carotid artery reactivity, brachial flow-mediated vasodilation, and retinal arteriolar calibers.
• Visuospatial and verbal memory scores improved, while executive function and psychomotor speed remained unchanged.

Conclusions:

• Longer-term consumption of mixed nuts, as part of a healthy diet, positively impacts brain vascular function in older adults.
• These vascular improvements may underlie the observed benefits in memory function.
• The study also demonstrated beneficial effects on peripheral vascular markers.