A recent study published in The American Journal of Clinical Nutrition investigates the associations between nut consumption and changes in cognitive performance.
Study: Higher versus lower nut consumption and changes in cognitive performance over two years in a population at risk of cognitive decline: a cohort study. Image Credit: CreatoraLab / Shutterstock.com
Are nuts good for brain health?
Diet is considered a major modifiable lifestyle factor and plays a vital role in regulating other risk factors for certain health conditions.
Peanuts and tree nuts are enriched with nutrients and have anti-inflammatory and antioxidant properties. In fact, the various nutrients and active compounds present in nuts can also elicit neuroprotective effects. Nevertheless, there is limited epidemiologic evidence for the associations between nut intake and cognitive performance.
While many cross-sectional studies support that cognitive function and nut consumption are positively related, prospective studies and randomized controlled trials (RCTs) have reported mixed results. Thus, existing evidence of the impact of nut intake on cognitive performance remains inconclusive.
About the study
In the present study, researchers prospectively assess the associations between the consumption of nuts and two-year changes in cognitive performance in a Spanish cohort of older adults at risk of cognitive decline. Obese or overweight community-dwelling individuals between 55 and 75 years of age with metabolic syndrome at baseline were eligible for inclusion.
Participants completed a food-frequency questionnaire that assessed the habitual intake of different food items in the past year. Nut consumption was stratified as less than one serving each week, one to two servings each week, three to six servings each week, and seven or more servings each week. Trained personnel assessed cognitive performance at baseline and after two years.
Eight neuropsychological tests were administered during personal interviews. Cognitive tests were standardized to a z-score for each participant using mean and standard deviation of baseline data.
The difference between scores was estimated to explore cognitive performance changes. Composite measures for a global assessment of cognitive function and three cognitive domains, including general cognition, executive function, and attention, were calculated.
The primary outcome was the two-year changes in the composite scores. Data on sociodemographics, lifestyle, food consumption, medical history, and anthropometrics were obtained at baseline.
Depressive symptoms were assessed using the Beck Depression Inventory. The associations of nut consumption with two-year cognitive function changes were examined using multivariable linear regression models.
The study included 6,630 participants with an average of 65, with females representing 48.4% of the study cohort. The daily average nut consumption was 1.7 g and 43.7 g in the lowest and highest consumption categories at baseline, respectively, with walnuts being the most consumed. Individuals with the highest consumption had higher education, better Mediterranean diet adherence, and higher physical activity than those with the lowest intake.
Furthermore, there were fewer current smokers and depressive individuals in the highest consumption category. Participants with the highest intake also had a lower waist circumference and body mass index (BMI) than those with the lowest intake.
A positive association between nut consumption and two-year cognitive performance changes was observed. In multivariable models, a one-serving of nuts daily was associated with more favorable changes in the general cognitive function and clock drawing test (CDT).
Participants consuming three to six servings of nuts every week had better evolution of cognitive performance at two years than those consuming less than one serving each week. This finding was not observed for the highest category of nut consumption. The associations between nut intake and two-year cognitive changes were similar in sensitivity analyses.
The researchers did not observe significant interactions of nut intake with education level, sex, smoking status, hypertension, hypercholesterolemia, or type 2 diabetes. The stratified analysis revealed an association between more frequent nut consumption and less cognitive decline only in those with depressive symptoms at baseline.
In the current study, higher nut consumption was associated with more favorable changes in CDT and general cognitive function, thus indicating a potential dose-response association. Synergistic interactions between depression and nut intake were also observed, which implies that individuals with depressive symptoms at baseline were likely to benefit more from nut consumption.
Taken together, higher nut consumption might delay cognitive decline over two years in older, overweight, or obese adults with metabolic syndrome. Nevertheless, additional epidemiologic and clinical studies are needed to corroborate these findings before dietary recommendations can be made for delaying or preventing dementia and cognitive impairment.
- Ni, J., Nishi, S. K., Babio, N., et al. (2023). Higher versus lower nut consumption and changes in cognitive performance over two years in a population at risk of cognitive decline: a cohort study. The American Journal of Clinical Nutrition. doi:10.1016/j.ajcnut.2023.05.032