Could Walnuts Help to Prevent Cognitive Decline?

Regular consumption of walnuts could help to delay cognitive decline in older adults who are at increased risk, according to the results of a recent study.

Because walnuts help to counteract oxidative stress and inflammation, researchers theorized that regular consumption could help to prevent cognitive decline in healthy older adults.

They conducted a randomized controlled trial involving 798 free-living older adults (aged 63 to 79 years) who were assigned to a diet enriched with walnuts 30g to 60g per day) or to a control diet with abstention from walnuts. At baseline, participants underwent a neurocognitive test battery. Testing was repeated after 2 years. Further, 108 participants underwent repeated structural and functional brain MRI.

Overall, 636 participants completed the study. Modified intention-to-treat analyses showed no difference between the 2 groups in global cognitive composite (mean changes of -0.072 and 0.086 in the walnut and control groups, respectively). However, brain MRI results indicated greater functional network recruitment in a working memory task within controls.

“Walnut supplementation for 2 years had no effect on cognition in healthy elders. However, brain fMRI and post hoc analyses by site suggest that walnuts might delay cognitive decline in subgroups at higher risk. These encouraging but inconclusive results warrant further investigation, particularly targeting disadvantaged populations, in whom greatest benefit could be expected,” the researchers concluded.

—Michael Potts

Reference:
Sala-Vila A, Valls-Pedret C, Rajaram S, et al. Effect of a 2-year diet intervention with walnuts on cognitive decline. The Walnuts And Healthy Aging (WAHA) study: a randomized controlled trial [published online January 7, 2020]. AJCN. https://doi.org/10.1093/ajcn/nqz328.