Metabolic and Environmental Biomarkers in Mild Cognitive Impairment and Dementia: An Exploratory Study

To determine the frequency with which suspected pathogenic factors, including metals and metabolites that might contribute to Alzheimer's disease (AD), may be found in patients with cognitive impairment through commonly available blood tests. A variety of serum studies, including metals, ammonia, homocysteine, vitamin B12, folate, thyroid tests, metabolic products, and inflammatory markers, were measured in two cohorts: one meeting mild cognitive impairment (MCI) criteria and the other meeting mild-to-moderate dementia (DE) criteria. Medications these patients received were reviewed. Metal abnormalities were detected in over half the subjects, including evidence of mercury, lead, and arsenic elevation as well as instances of excessive essential metals, iron (Fe), and copper. Some metal aberration was detected in 64% of the DE group and 66% of the MCI group. Females were more likely to have elevated copper, consistent with hormonal effects on copper excretion. Homocysteinemia was the most common abnormality, detected in 71% with DE and 67% with MCI, while methylmalonic acid was not elevated. Slight hyperammonemia was moderately common (38%) suggesting a hepatic factor in this subset. Findings of moderate insulin resistance were present in nearly half (44% DE, 52% MCI). Sixty of 65 (92%) had at least one abnormal biomarker and 60% had two or more. The most common drug taken by the total cohort was proton pump inhibitors at 22% DE and 38% MCI. This study suggests that both toxic metals and excessive vital metals such as copper and iron, as well as common metabolic and hepatic factors are detectable at both stages of MCI and DE. There appears to be a multiplicity of provocative factors leading to DE. Individualized interventions based on these parameters may be a means to reduce cognitive decline leading to DE. A more comprehensive prospective study of these environmental and metabolic factors with corrective early interventions appears warranted.