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A groundbreaking study published in JAMA Network Open reveals that higher levels of environmental metals in urine are associated with poorer cognitive performance and a heightened risk of dementia. The research, led by Dr. Arce Domingo-Relloso from Columbia University’s Mailman School of Public Health, underscores the potential role of metal exposure in cognitive decline and dementia prevention strategies.
Study Overview
The prospective cohort study involved 6303 participants, aged 45 to 84 years, from six U.S. centers between 2000 and 2002. All participants were initially free of cardiovascular disease and were followed through 2018. Researchers analyzed urinary concentrations of nine metals, including arsenic, cadmium, cobalt, copper, and zinc, and assessed cognitive performance using neuropsychological tests like the Digit Symbol Coding and Digit Span tests.
During a median follow-up period of 16.8 years for participants without dementia, 559 cases of dementia were identified.
Key Findings
Higher urinary concentrations of several metals correlated with lower cognitive test scores and increased dementia risk:
- Cognitive Decline: Elevated levels of arsenic, cobalt, copper, uranium, and zinc were associated with slower mental processing speeds and reduced scores on the Digit Symbol Coding test.
- APOE4 Carriers at Higher Risk: Effects were particularly pronounced in carriers of the APOE4 allele, a genetic marker for Alzheimer’s disease.
- Dementia Risk: Individuals with urinary metal levels in the 95th percentile faced a 71% higher risk of developing dementia compared to those at the 25th percentile.
Implications for Public Health
The study highlights the modifiable nature of metal exposure and its potential role in early dementia prevention. “These findings could inform early screening and precision interventions for dementia prevention based on individuals’ metal exposure and genetic profiles,” the researchers noted.
Limitations and Future Research
While the study provides compelling evidence, it has limitations. Dementia diagnoses relied on nonspecific codes, and some cases may have been missed due to patient mortality or loss to follow-up. Additionally, the sample size was insufficient to examine associations among carriers of two APOE4 alleles.
Funding and Disclosures
The research was supported by the National Heart, Lung, and Blood Institute. Several authors disclosed receiving grants and other financial support from the National Institutes of Health and other organizations.
Takeaway
This study reinforces the need for monitoring environmental exposures and tailoring interventions to reduce dementia risk, particularly in genetically vulnerable populations. As the global burden of dementia rises, addressing environmental factors like metal exposure could be a vital step toward mitigating its impact.
