Dementia Risk Associated With Higher Exposure to Metals: Study

Exposure to nine different metals brings an even greater risk of cognitive decline for those carrying a specific gene known as APOE4.

The findings of a new study suggests that elevated levels of specific metals in urine are associated with reduced cognitive performance and an increased risk of developing neurodegenerative conditions, such as dementia and Alzheimer’s disease.

Data has already shown that heavy metals are toxic to the brain and may be linked not only with decreased cognitive performance, but have long been suspected of increasing risks of Alzheimer’s disease and dementia. However, research exploring the link is limited.

According to findings published in the journal JAMA Network Open earlier this month, high levels of arsenic, cadmium, cobalt, copper, lead, manganese, tungsten, uranium and zinc in the urine increase a person’s risk of suffering from dementia by 71%, and that risk increases for individuals carrying a specific gene known as APOE4.

Researchers from Columbia University Mailman School of Public Health in New York led by Dr. Arce Domingo-Relloso, studied more than 6,000 participants involved in the Multi-Ethnic Study of Atherosclerosis from July 2000 to August 2002, with follow-ups through 2018.

Urine samples were collected from participants and levels of arsenic, cadmium, cobalt, copper, lead, manganese, tungsten, uranium and zinc were measured. Patients were also screened for a specific gene known as APOE4. Patients were then given various cognitive tests to measure their ability to think, the ability to pay attention, process information, and remember things.

A total of 559 cases of dementia were diagnosed and researchers said there was a link between low cognitive scoring and higher levels of metals in the urine.

When all nine metals were present at high levels in the individual’s urine, there was a 71% greater chance of cognitive decline, but each metal was individually linked with an increased risk of developing dementia as well. For example, the increased risk of dementia ranged from 15% for patients who had high levels of tungsten in the urine to 46% for patients with high levels of uranium.

Carriers of the APOE4 gene were even more likely to experience lower cognitive scores if they had higher levels of manganese in their urine.

Researchers said the findings are significant not just because they highlight a link between heavy metal exposure and increased likelihood of developing dementia, but because the risk was also seen for essential metals that are necessary for normal biological functioning.

Copper is needed for certain neurological functions, manganese is necessary for energy production and blood clotting, and zinc supports the body’s immune system and helps the cells in the body grow and divide.

While these metals are needed in the body for different functions, the presence of the metals at different levels may pose a risk of cognitive decline and dementia, especially if the individual is a carrier of the APOE4 gene.

Researchers said the findings can help improve early screening and interventions for dementia based on genetic profiles and metal exposure. However, more research is needed to determine the link between metal exposure and the risk of dementia and how the APOE4 gene may increase that risk.