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Copper May Help Maintain Brain Health After Stroke
Last reviewed: 03.08.2025
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A new study reveals the brain-boosting power of copper: The right amount may help older adults stay sharp, especially after a stroke. An observational study of older Americans found that higher dietary copper intake was associated with better cognitive function, especially in those with a history of stroke. The study is published in Scientific Reports.
Prerequisites
The prevalence of cognitive impairment is steadily increasing worldwide, mainly due to the aging population. Cognitive decline is an important feature of all forms of dementia, from mild cognitive impairment to Alzheimer's disease.
The latest estimates suggest that the number of people with dementia will reach 152.8 million by 2050, highlighting the need to develop strategies to reduce the risk of cognitive impairment.
Supplementing with dietary essential micronutrients — vitamins and minerals — has been seen in recent years as a valuable approach to improving cognitive function and preventing dementia, especially in older adults. Research has shown that imbalances of certain micronutrients, such as zinc, selenium, and copper, in the brain can lead to cognitive impairment and subsequent development of neurodegenerative diseases.
Copper is an important micronutrient required for the development and functioning of the nervous system. However, the brain requires optimal levels of copper for normal functioning: its deficiency can cause neurological disorders, and its excess can lead to oxidative stress and neurodegeneration.
In the current study, the researchers examined the nonlinear dose-response relationship between dietary copper intake and cognitive function in Americans aged 60 years and older.
Methodology
The study analyzed data from 2,420 participants in the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2014. The NHANES sample is representative of the U.S. adult population.
Information on dietary copper intake was obtained from two 24-hour dietary recall questionnaires. To assess memory and executive function, participants completed four tests of cognitive function: the immediate and delayed verbal word list recall tests (CERAD-IRT and CERAD-DRT), the digit symbol substitution test (DSST), and the animal verbal fluency test (AFT). A mean global cognitive score was calculated from the results of all four tests.
- The CERAD-IRT and CERAD-DRT assessed the ability to acquire new lexical information.
- The DSST measured information processing speed and executive function.
- The AFT assessed verbal and executive abilities.
Key Results
Participants with the highest dietary copper intake had higher cognitive scores than those with the lowest intake. Cognitive function gradually improved as copper intake increased, indicating a positive but nonlinear dose-response relationship.
Researchers have identified optimal copper intake thresholds:
- 1.63 mg/day for DSST;
- 1.42 mg/day for AFT;
- 1.22 mg/day for global cognitive score.
A positive association between copper intake and cognitive function was observed at intakes below these thresholds. Above the thresholds, the association had an inverted L-shape and lost statistical significance. This suggests that after a certain level, copper intake no longer improves cognitive function.
Subgroup analysis showed that the positive effect of copper on global cognitive score was particularly pronounced in participants with a history of stroke: the increase in global cognitive function Z-score in this group was statistically significant (p for interaction = 0.009).
Significance of the study
The study highlights the importance of adequate dietary copper intake to improve cognitive function in older adults, especially stroke survivors.
Copper regulates many physiological processes: neurotransmitter synthesis, cellular energy production, and antioxidant protection. It serves as a cofactor for a number of enzymes involved in brain function. Disruption of copper homeostasis is associated with neurodegenerative diseases, including Wilson's disease and Alzheimer's disease.
The beneficial effect of copper was particularly noticeable in participants with a history of stroke. Existing data also indicate a protective effect of copper in reducing the risk of stroke and reducing neuronal damage in ischemic stroke.
Copper is involved in the work of antioxidant enzymes, reducing the formation of free radicals and preventing oxidative damage to lipids in the brain. It also promotes the transition of macrophages from a pro- to an anti-inflammatory phenotype, which prevents neuroinflammation and provides neuroprotection, supporting cognitive abilities.
The improvement of cognitive functions through copper is also associated with its role in the synthesis of the neurotransmitter acetylcholine, which is important for learning and memory.
Overall, the study suggests that optimal copper intake (≈ 1.22 mg/day) may improve cognitive function in older adults, especially those with stroke. Randomized controlled trials are needed to confirm these findings.
However, establishing causal relationships is impossible due to the cross-sectional design of the study and the possible influence of unaccounted dietary and behavioral factors.