Study Finds Nut Consumption Promotes Memory and Brain Health in Older People

A recent study published in clinical nutrition evaluated the long-term effects of various nut consumption on cerebrovascular function and cognitive performance.

study: Long-term intake of mixed nuts improves cerebrovascular function and memory: a randomized controlled crossover trial in the elderly.. Image credit: umaruchan4678 / Shutterstock.com

health benefits of nuts

Nutritional interventions are an effective approach to reduce or prevent the burden of age-related conditions such as cognitive decline and cardiovascular disease. To this end, previous research suggests that nut consumption protects against cognitive impairment.
Studies including nuts in the Mediterranean diet have also reported cognitive benefits in older adults. Similarly, randomized controlled trials (RCTs) have demonstrated benefits of nuts for vascular dysfunction. However, there is limited evidence about the effects of nut consumption on central arteries near the brain.

About research

In this study, researchers are evaluating the effects of long-term consumption of mixed nuts on cerebrovascular function in older adults. Eligible participants were healthy men and postmenopausal women aged 60–70 years with a stable body weight and body mass index (BMI) within her 25 kg/m.² ～35kg/m². Subjects were excluded if they had nut intolerance or allergy, symptoms that interfered with study results, or contraindications for magnetic resonance imaging (MRI).

The current study was a single-blind RCT with a crossover design that included a 16-week intervention and control period, with an 8-week washout period in between. During the intervention period, participants consumed 60 grams of mixed nuts daily, including cashews, walnuts, hazelnuts, and pistachios.

Participants were instructed to adhere to the Dutch food-based dietary guidelines and avoid consuming products rich in n3-polyunsaturated fatty acids (PUFAs). At the end of each period, peripheral and cerebral vascular function and cognitive performance were assessed. Cerebral blood flow (CBF) was quantified using pseudo-continuous arterial spin-labeled MRI.

Cognitive abilities were tested using the Cambridge Neuropsychological Test Automated Battery. In addition, effects on retinal microvasculature, arteriosclerosis, and endothelial function were also investigated. Differences between intervention and control periods were assessed using a linear mixed model.

research result

The current study included 28 individuals, who were gender-matched. Participants had an average age of 64.6 years and an average BMI of 27.9 kg/m2.².

The mixed nut intervention was well tolerated, with no protocol deviations or serious adverse events reported. This intervention reduced cholesterol and carbohydrate intake and increased fiber intake compared to controls.

Total fat intake increased, saturated fatty acid (SFA) intake decreased, and cis-monounsaturated fatty acid (cis-MUFA), α-linolenic acid, linolenic acid, and cis-PUFA intake increased after the mixed nut intervention. quantity has increased. After the intervention he had his SFA drop by 0.9 percentage points, largely due to a decrease in palmitate.

The intervention increased total PUFA by 1.3 percentage points, but total MUFA remained unchanged. There were no significant differences between the intervention and control periods for whole-brain, cortical, subcortical, or gray matter CBF. However, cluster-by-cluster analysis showed significantly higher regional CBFs across the three clusters.

Cluster 1 increased CBF by 5 ml/100 g/min. The average probability of its location was in the right upper parietal lobe, lateral occipital cortex, and superior frontal gyrus, precentral, postcentral, and middle frontal gyrus. CBF increased by 5.4 ml/100 g/min and 5.6 ml/100 g/min in clusters 2 and 3, respectively.

The average probabilities of cluster 2 location were left precentral, central frontal, superior frontal, and postcentral gyrus. The mean probability of cluster 3 location was bilateral in the medial frontal cortex, frontal pole, cingulate and paracingulate gyrus. Post-intervention carotid reactivity was 0.7 percentage points higher than controls.

This intervention significantly reduced the pulse wave velocity from the carotid artery to the femur. Brachial artery blood flow-mediated vasodilation, central retinal arteriolar equivalent, and arteriole-to-venule ratio increased after intervention. Central retinal venule equivalents did not change after intervention.

Performance on the visuospatial memory task improved after the intervention, and the number of correct words on the verbal memory task increased by 16% after the intervention. There were no differences in word recognition, psychomotor speed, executive function, stress, quality of life, sleep quality, and mood between the intervention and control periods.

Conclusion

After the mixed nuts intervention, an increase in local CBF was observed within three clusters: left frontal lobe, bilateral prefrontal cortex, right parietal lobe and frontal lobe.

There were no changes in psychomotor speed or executive function, and an increase in cognitive performance within memory areas was also observed. Similarly, improvements in various properties of the peripheral vascular tree were evident after the mixed nut intervention.