Brain mercury in neurodegenerative disorders

Area of Science:

• Neuroscience
• Toxicology
• Neuropathology

Background:

• Trace element neurotoxicity is a proposed factor in Alzheimer's disease etiology.
• This study investigated mercury concentrations in brain tissue of Alzheimer's disease (AD) and multiple sclerosis (MS) patients compared to controls.
• Potential sources of mercury include dental amalgam, diet, and occupational exposure.

Purpose of the Study:

• To determine mercury concentrations in seven distinct brain regions of individuals with AD, MS, and controls.
• To compare mercury and mercury/selenium molar ratios across these groups.

Main Methods:

• Autopsy-frozen brain specimens from control, AD, and MS subjects were analyzed.
• Seven brain regions were examined: frontal cortex, temporal cortex, occipital cortex, putamen, hippocampus, corona radiata, and corpus callosum.
• Instrumental neutron activation analysis (INAA) and radiochemical neutron activation analysis (RNAA) were used to measure mercury and selenium concentrations.

Main Results:

• Mercury concentrations and mercury/selenium molar ratios were significantly lower in the hippocampi of MS patients compared to age-matched controls.
• No statistically significant differences in mercury or mercury/selenium ratios were found in the other six brain regions among the groups.
• This suggests a localized difference in mercury levels in MS patients, not a general increase.

Conclusions:

• The study found no evidence supporting a significant role for mercury in the pathogenesis of Alzheimer's disease or multiple sclerosis.
• Observed mercury levels in the brains of AD and MS patients were not significantly higher than in control subjects.
• These findings do not support the hypothesis that mercury neurotoxicity is a primary cause of these neurological conditions.