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Cognitive impairment is increasing globally. All stages of dementia are marked by declines in memory and executive function. Previous research has examined whether micronutrient levels may relate to cognitive resilience.

Copper is an essential trace element that participates in neuronal energy metabolism, neurotransmitter synthesis, and antioxidant regulation. Previous studies have proposed both protective and harmful roles for copper in neurodegenerative disease, depending on its bioavailability and concentration in neural tissue.

In the study, "Association between dietary copper intake and cognitive function in American older adults, " published in Scientific Reports, researchers designed a cross-sectional analysis to evaluate the relationship between dietary copper consumption and cognitive performance.

A cohort of 2, 420 participants aged 60 years or older was selected from the 2011–2014 National Health and Nutrition Examination Survey (NHANES). All participants had complete data on dietary intake and cognitive function.

Dietary copper intake was derived from two averaged 24-hour dietary recalls. Cognitive function was measured using four instruments: the Digit Symbol Substitution Test (DSST), the Animal Fluency Test (AFT), the immediate and delayed recall subtests of the CERAD protocol, and a composite Z score reflecting global cognition. Copper intake was stratified into quartiles.

Multivariate linear regression models were used to test associations. In the fully adjusted model, participants in the highest copper intake quartile (Q4, ≥1.44 mg/day) had higher scores than those in the lowest quartile (Q1, <0.76 mg/day): DSST (β=3.80, 95% CI 1.90, 5.70), AFT (β=1.23, 95% CI 0.48, 1.99), CERAD-DRT (β=0.47, 95% CI 0.15, 0.80), and Z score (β=0.20, 95% CI 0.10, 0.29). No statistically significant association with CERAD-IRT was found in the fully adjusted model (β=0.58, 95% CI −0.06, 1.22).

Participants in the higher copper intake quartiles were more likely to be male, non-Hispanic white, married, and higher income, with lower smoking prevalence and more favorable nutritional profiles, including higher intake of zinc, iron, selenium, and total energy.

Spline-based regression modeling showed an inverted L-shaped association between copper intake and DSST, AFT, and Z score. Cognitive test performance improved with copper intake up to thresholds of 1.63 mg/day (DSST), 1.42 mg/day (AFT), and 1.22 mg/day (Z score).

Beyond these thresholds, associations with DSST, AFT, and Z score lost statistical significance, showing near zero change and wide confidence intervals..

Participants with a history of stroke showed a stronger association between copper intake and global cognition. In this subgroup, Q4 intake was associated with a higher Z score than Q1 (β=0.55, 95% CI 0.24, 0.86; p for interaction=0.009). No significant interaction effects were observed for other demographic or clinical variables.

Authors conclude that copper intake was associated with better cognitive function test scores in older adults. Associations were strongest at moderate intake levels and most pronounced in individuals with prior stroke.

Although the precise mechanisms underlying the relationship between dietary copper intake and cognitive function remain unknown, the authors state that the findings "… are considered biologically plausible. Dietary copper is crucial for brain health and may confer protective effects on cognitive function through its involvement in antioxidant defense, neurotransmitter synthesis, and energy metabolism."

Written for you by our author Justin Jackson, edited by Sadie Harley, and fact-checked and reviewed by Andrew Zinin—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you.

More information: Weiai Jia et al, Association between dietary copper intake and cognitive function in American older adults: NHANES 2011–2014, Scientific Reports (2025). DOI: 10.1038/s41598-025-09280-9  Journal information: Scientific Reports

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