Study: Eating nuts regularly may slow cognitive decline

Key takeaways:

• For older adults at risk for cognitive decline, frequent nut consumption was associated with smaller decline in general cognitive performance.
• The researchers observed a dose-dependent response: more was better.

Frequent nut consumption was linked to reduced cognitive decline for at-risk older adults, according to the results of research published in The American Journal of Clinical Nutrition.

As nutrient-dense foods that are rich in neuroprotective components, peanuts and tree nuts could benefit cognitive health, Jiaqi Ni, a PhD candidate in nutrition and metabolism at The University of Rovira i Virgili in Spain, and colleagues wrote, but current evidence is inconsistent and limited.

“The myriad of nutrients and biologically active compounds that nuts contain, such as unsaturated fatty acids, high-quality vegetable protein, an array of vitamins and beneficial minerals, dietary fiber, phenolic compounds, and phytosterols, appear to have neuroprotective effect,” they wrote.

Ni and colleagues conducted a cohort study to prospectively assess the connections between nut consumption and 2-year changes in cognitive performance among older adults at risk for cognitive decline — “a common harbinger of dementia,” they said.

“By 2050, dementia prevalence is estimated to triple, and currently, there are no effective curative treatments available,” Ni and colleagues wrote. “Therefore, proactive strategies targeting modifiable risk factors to prevent or delay the onset or progression of cognitive decline are imperative.”

The study included 6,630 participants aged 55 to 75 years, 48.4% of whom were women, with metabolic syndrome and overweight or obesity. They underwent a comprehensive battery of neuropsychological tests, the researchers wrote, and completed a validated semiquantitative food frequency questionnaire at baseline and after a 2-year follow-up. The researchers used composite cognitive scores to evaluate general, attention, global and executive function domains.

Ni and colleagues found that, for older adults at risk for cognitive decline, frequent nut consumption was associated with smaller decline in general cognitive performance over the “relatively short” 2-year period. The findings should be verified with randomized clinical trials, they wrote.

Various amounts of nut consumption were positively associated with 2-year changes in general cognitive function (P trend < .001). For example, those who consumed seven or more servings per week and those who consumed three to seven servings per week showed changes in general cognitive performance that the researchers said were more favorable compared with participants who consumed less than one serving per week, with beta z scores of 0.13 (0.06-0.2) and 0.06 (95% CI, 0-0.12), respectively.

The results indicate a possible dose-response relationship, Ni and colleagues wrote.

“Our results show that a higher frequency of nut consumption is associated with favorable changes in the general cognitive function composite and Clock Drawing Test score” — referring to a screening tool that assesses loss of cognition — “suggesting a potential dose-response relationship between nut consumption and a delay in cognitive decline over the period of 2 years, regardless of the baseline cognitive status, sociodemographic, cardiometabolic, and lifestyle factors including diet, in older adults with overweight/obesity, metabolic syndrome, and at risk of cognitive decline,” they wrote.

The researchers did not observe significant changes in the multivariable-adjusted models for other cognitive domains but wrote that they additionally found “a potential synergistic interaction between nut consumption and depression,” which suggested that participants who had depressive symptomatology at baseline tended to benefit more from the consumption of nuts than those without depression. Relatedly, data from the National Health and Nutrition Examination Survey published in 2019 showed that nut consumption — particularly walnuts — was associated with less frequent depressive symptoms.

References:

• Arab L, et al. Nutrients. 2019;doi:10.3390/nu11020275.
• Ni J, et al. Am J Clin Nutr. 2023;doi:10.1016/j.ajcnut.2023.05.032.