Cadmium, a harmful heavy metal present in the environment—air, water, food, and soil—has been linked to various health issues. A recent study highlighted in the September 4, 2024, online edition of Neurology®, the journal from the American Academy of Neurology, explored whether cadmium exposure affected cognitive functions like thinking and memory. Although the overall analysis revealed no link, a deeper investigation into separate groups showed that cadmium exposure might be connected to cognitive issues in white individuals, while no such correlation was observed in Black participants. This research does not establish causation, merely suggesting a connection for white individuals.
Cadmium is a highly dangerous heavy metal that primarily enters the human body through smoking, inhaling contaminated air, and consuming tainted food. It is released into the environment through various industrial and agricultural processes.
“Given the prevalence and substantial impact of dementia on families and society, it’s crucial to pinpoint early cognitive risk factors that could be influenced by changes in behavior or environmental factors,” said study author Liping Lu, MD, PhD, from Columbia University in New York City.
The study involved 2,172 individuals with an average age of 64, all of whom exhibited no initial cognitive issues. Among the participants, 39% were Black and 61% were white. Urinary cadmium levels were measured at the study’s start, and participants underwent annual thinking and memory assessments for about 10 years.
Over the study’s duration, 195 participants experienced cognitive decline. In evaluating the entire group, researchers found no significant relationship between cadmium levels and cognitive decline. Yet, when analyzing Black and white participants independently, it was discovered that white individuals with elevated cadmium levels had a higher risk of cognitive impairment. No such link was established for Black individuals.
When categorizing participants based on cadmium levels, it emerged that white participants with high levels were twice as likely to develop cognitive issues compared to those with lower levels, accounting for other influencing factors like physical activity, alcohol consumption, and education. Specifically, 9.2% of individuals with high cadmium levels experienced thinking and memory challenges, in contrast to 6.7% of those with lower levels.
Lu suggested that the disparity between white and Black participants might be related to smoking habits. In dividing participants into three groups based on cadmium concentration, it was noted that white individuals with the highest cadmium levels averaged 23 pack-years of smoking, while Black participants at the highest levels averaged only nine pack-years. Pack-years serve as a metric to quantify smoking over time, calculated by multiplying the number of packs smoked per day by the number of years of smoking. Thus, a figure of 23 pack-years could represent smoking one pack daily for 23 years or two packs daily for roughly 11.5 years.
“These findings require further validation through research that assesses cadmium levels longitudinally, includes a greater number of participants, and maintains longer follow-up periods. Nonetheless, it’s crucial to minimize cadmium exposure through improved regulations on air and water quality or by individuals quitting smoking or avoiding exposure to tobacco smoke,” Lu stated.
A key limitation of the study was that cadmium levels were only measured at the baseline, leaving open the possibility that exposure could have varied over time.
This research received funding from the National Institute of Neurological Disorders and Stroke and the National Institute on Aging.
