Urinary Metals Linked to Increased Dementia Risk

TOPLINE:

Higher levels of environmental metals in urine are associated with poorer cognitive performance and an increased risk for dementia, new research suggests.

METHODOLOGY:

• This multicenter prospective cohort study included 6303 participants from six US study centers from 2000 to 2002, with follow-up through 2018.
• Participants were aged 45-84 years (median age at baseline, 60 years; 52% women) and were free of diagnosed cardiovascular disease.
• Researchers measured urinary levels of arsenic, cadmium, cobalt, copper, lead, manganese, tungsten, uranium, and zinc.
• Neuropsychological assessments included the Digit Symbol Coding, Cognitive Abilities Screening Instrument, and Digit Span tests.
• The median follow-up duration was 11.7 years for participants with dementia and 16.8 years for those without; 559 cases of dementia were identified during the study.

TAKEAWAY:

• Lower Digit Symbol Coding scores were associated with higher urinary concentrations of arsenic (mean difference [MD] in score per interquartile range [IQR] increase, -0.03), cobalt (MD per IQR increase, -0.05), copper (MD per IQR increase, -0.05), uranium (MD per IQR increase, -0.04), and zinc (MD per IQR increase, -0.03).
• Effects for cobalt, uranium, and zinc were stronger in apolipoprotein epsilon 4 allele (APOE4) carriers vs noncarriers.
• Higher urinary levels of copper were associated with lower Digit Span scores (MD, -0.043) and elevated levels of copper (MD, -0.028) and zinc (MD, -0.024) were associated with lower global cognitive scores.
• Individuals with urinary levels of the nine-metal mixture at the 95th percentile had a 71% higher risk for dementia compared to those with levels at the 25th percentile, with the risk more pronounced in APOE4 carriers than in noncarriers (MD, -0.30 vs -0.10, respectively).

IN PRACTICE:

“We found an inverse association of essential and nonessential metals in urine, both individually and as a mixture, with the speed of mental operations, as well as a positive association of urinary metal levels with dementia risk. As metal exposure and levels in the body are modifiable, these findings could inform early screening and precision interventions for dementia prevention based on individuals’ metal exposure and genetic profiles,” the investigators wrote.

SOURCE:

The study was led by Arce Domingo-Relloso, PhD, Columbia University Mailman School of Public Health, New York City. It was published online December 2 in JAMA Network Open.

LIMITATIONS:

Data may have been missed for patients with dementia who were never hospitalized, died, or were lost to follow-up. The dementia diagnosis included nonspecific International Classification of Diseases codes, potentially leading to false-positive reports. In addition, the sample size was not sufficient to evaluate the associations between metal exposure and cognitive test scores for carriers of two APOE4 alleles.

DISCLOSURES:

The study was supported by the National Heart, Lung, and Blood Institute. Several authors reported receiving grants from the National Institutes of Health and consulting fees, editorial stipends, teaching fees, or unrelated grant funding from various sources, which are fully listed in the original article. 

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.