Alzheimer's disease, dental amalgam and mercury

Background. Mercury, or Hg, is a neurotoxin that has been speculated to pla y a role in the pathogenesis of Alzheimer's disease, or AD. Dental amalgam releases low levels of Hg Gaper and isa potential source of Hg for a large segment of the adult population. Methods. The authors studied 68 subjects with AD and 33 control subjects wi thout AD to determine Hg levels in multiple brain regions at autopsy and to ascertain the subjects' dental amalgam status and history. The subjects we re from central Kentucky and Elm Grove, Wis, The authors conducted dental a malgam assessments during the lives of the majority of subjects and in some subjects at the time of autopsy only. The authors also determined three de ntal amalgam index scores-Event (placement, repair or removal of amalgam), Location and Time In Mouth-in addition to the numbers of and surface area o f occlusal amal gam restorations. The authors determined Hg levels in multi ple brain reigions and performed full neuropathologic evaluations to confir m the normal status of the brain or the presence of AD. Results. The authors found no significant association of AD with the number , surface area or history of having dental amalgam restorations. They also found no statistically significant differences in brain Hg level between su bjects with AD and control subjects. Conclusions. Hg in dental amalgam restorations does not appear to be a neur otoxic factor in the pathogenesis of AD. The authors found that brain Hg le vels are not associated with dental amalgam, either from existing amalgam r estorations or according to subjects' dental amalgam restoration history. Clinical Implications. Dental amalgam restorations, regardless of number, o cclusal surface area or time, do not relate to brain Hg levels.