A Cross-Sectional Study of Blood Ethylmercury Levels and Cognitive Decline Among Older Adults and the Elderly in the United States

Abstract

Cognitive health is an emerging public health concern for the aging American population. Mercury (Hg) is a toxic element that can cause nervous system damage. This hypothesis-testing study evaluated the relationship between blood ethyl-Hg levels and cognitive decline in an older adult and elderly American population. A total of 1,821,663 weighted-persons between 60–80 years old with detectable blood ethyl-Hg levels within the 2011–2012 National Health and Nutritional Examination Survey were examined. Those persons with blood ethyl-Hg levels greater than the median were deemed the higher ethyl-Hg exposure group and those with ethyl-Hg levels less than the median were deemed the lower ethyl-Hg exposure group. Three tests were utilized to measure cognitive function: 1) Consortium to Establish a Registry for Alzheimer’s Disease – Word List Learning (CERAD W-L) delayed recall test, 2) animal fluency test, and 3) Digit Symbol Substitution Test. Each cognitive test score was categorized as higher for those with scores greater than the median and lower for those with scores less than the median. Survey logistic regression modeling with covariates was used to analyze the data for the relationship between blood ethyl-Hg levels and cognitive function scores. Significantly increased risks for lower animal fluency test (odds ratio (OR) = 13.652, p = 0.0029) and CERAD W-L delayed recall test (OR = 6.401, p = 0.0433) scores were observed among the higher ethyl-Hg exposure group as compared to the lower ethyl-Hg exposure group. This study supports the hypothesis that increased ethyl-Hg exposure is associated with significant cognitive decline in older adult and elderly Americans.

Methylmercury Impact on Adult Neurogenesis: Is the Worst Yet to Come From Recent Brazilian Environmental Disasters?

“…Interestingly, following a detoxification dietary regime, his memory partially improved as the levels of mercury dropped in his body (Foley et al, 2020). Accordingly, in another study the authors found a positive correlation between the blood levels of ethylmercury and cognitive decline in older adults and elderly American populations (Geier et al, 2019). Furthermore, other evidences also support a possible long-term effect of mercury toxicity due to pre or perinatal exposure.…”

Exposición a la contaminación antropogénica por mercurio y sus efectos en la salud. Revisión Bibliográfica.

“…Con respecto a las enfermedades del sistema nervioso, estas son las que presentan efectos más visibles, mediante la odds ratio; sobresale el deterioro cognitivo en adultos (Geier et al, 2019). Esto podría deberse a que los adultos mayores acumulan más cantidad de Hg en su organismo con la edad, por lo cual dicha población es especialmente susceptible.…”

Toxic Environmental Factors and their Association with the Development of Dementia: a Mini Review on Heavy Metals and Ambient Particulate Matter

“…Geier DA, et al, in their study provide epidemiological data, which linked the increase of ethyl-mercury levels in the blood with the cognitive impairment of the elderly ( 27 ). Also, Sun YH, et al, conducted a study in which they discovered that individuals who were exposed to mercury via dental amalgam, had an increased ratio of 1,132 on developing Alzheimer’s disease, in comparison to those who were not exposed at all ( 28 ).…”