The study: Investigating walnut consumption and cognitive trajectories in a representative sample of older US adults. Nicholas J. Bishop and Krystle E. Zuniga. Public Health Nutrition , Volume 24 , Issue 7 , May 2021 , pp. 1741 – 1752.
Purpose: To estimate the association between whole walnut intake and cognitive change in a sample of 3632 US adults aged 65 years and older.
Method: This was a secondary analysis of dietary data and health outcome from the Health and Retirement Study and Health Care and Nutrition Study.
Conclusions: “We identified an association between walnut consumption and cognitive function in older adults, although we did not find that walnut consumption was protective against age-related cognitive decline.”
Financial support: This research was funded by the California Walnut Commission.
Comment: Eating walnuts tracks with cognitive function in this sample, but has no particular effect on it. As I read them, the conclusions put a positive spin on a null finding, a classic example of “interpretation bias.” The Walnut Commission paid for the study and this interpretation helps to sell walnuts. I think walnuts are great but wish the California Walnut Commission would stay out of this kind of marketing research.