Parkinson's Disease and Mercury

Abstract

The British physician James Parkinson reported in a publication in 1817 the clinical symptomatology in paralysis agitans or shaking palsy. The name of this disorder today is Parkinson's disease (PD).

Parkinsonism is characterized by hypokinesia, rigidity, tremor, symptoms from the vegetative nervous system, and in some cases dementia. Tremor is the most characteristic, and often the first symptom in Parkinson's disease.2 A still more incapacitating symptom is akinesia, which for the patients with the disorder results in augmenting difficulties at every movement.

The etiology is known in 25% of the cases of Parkinson's disease (medicaments, poisonings, cerebrospinal meningitis, etc.), and in 75% of the cases the etiology is unknown.1 Cases of unknown etiology are named idiopatic Parkinson's disease.

Parkinson's disease has probably a multifactorial etiology involving genetic, environmental, trauma and possibly other factors.

Full text

1. Toften 24, N-8610 Grubhei, Norway.
Parkinson's Disease and Mercury
Geir Bjørklund1
The British physician James Parkinson
reported in a publication in 1817 the clinical
symptomatology in paralysis agitans or shak-
ing palsy. The name of this disorder today is
Parkinson's disease (PD).
Parkinsonism is characterized by hypo-
kinesia, rigidity, tremor, symptoms from the
vegetative nervous system, and in some cases
dementia.1 Tremor is the most characteris-
tic, and often the first symptom in Parkin-
son's disease.2 A still more incapacitating
symptom is akinesia, which for the patients
with the disorder results in augmenting dif-
ficulties at every movement.2
The etiology is known in 25% of the cases
of Parkinson's disease (medicaments,
poisonings, cerebrospinal meningitis, etc.),
and in 75% of the cases the etiology is
unknown.1 Cases of unknown etiology are
named idiopatic Parkinson's disease.
Parkinson's disease has probably a multi-
factorial etiology involving genetic, envi-
ronmental, trauma and possibly other fac-
tors.3
The shortage of neuro-transmitters, such
as mono-amines, is well established in the
etiology of Parkinson's disease.2 Studies of
Parkinson patients have demonstrated low
levels of monoamine transmitters encoun-
tered in the basal ganglia, decreased values
of HVA and 5-HIFAA in the cerebrospinal
fluid, and loss of the dark melanin pigment
in the dopaminergic substantia nigra (ergon
= work, niger = black) of the basal ganglia.2
A failure of the neurons in the substantia
nigra result in decreased production of
dopamine and leads secondarily to a loss of
function in the corpus striatum.2 The conse-
quence of this process is the clinical picture
of Parkinson's disease.
Heavy metals, like mercury and copper,
can produce lesions of the basal ganglia,
with symptoms like hyperkinesia.2 Accord-
ing to Komulainen and Tuomisto4 copper
has a significant action on adrenergic neu-
rons.
Researchers at the Henry Ford Hospital in
Detroit, Michigan have studied Parkinson's
disease with respect to heavy metal expo-
sure.5 They have calculated mortality rates
for Parkinson's disease in Michigan counties
for 1986-1988 with respect to potential heavy
metal exposure (iron, zinc, copper, mercury,
magnesium, and manganese) from industry
based on recent census data. The death rates
are statistically significantly higher in coun-
ties with an industry in the chemical, paper,
iron or copper related-industrial categories
(ICs) (p < 0.05) than counties without these
industries.5 The authors concluded: “These
ecologic findings suggest a geographic as-
sociation between PD mortality and the in-
dustrial use of heavy metals.”
Ngim and Devathasan6 have done a case-
control study among the multiethnic popula-
tion of Singapore. They tested the hypoth-
esis that a high level of body burden mercury
is associated with an increased risk of Par-
kinson's disease. In 54 cases of idiopathic
Parkinson's disease and 95 hospital-based
controls, detailed interviews were com-
pleted.6 The two groups were matched for
age, sex and ethnicity, between July 1985
and July 1987. The researchers found that
there was a clear monotonic dose-response
association between blood mercury levels
and Parkinson's disease. The result was ad-
justed for potential confounding factors, in-
cluding dietary fish intake, medications,
smoking and alcohol consumption.6 Scalp
hair mercury was shown to be a poor predic-
tor of the risk of Parkinson's disease after
adjustment.
Ngim and Devathasan6 listed the follow-
ing factors that could contribute to the body
burden of mercury: dietary fish intake, eth-
nic over-the-counter medications, occupa-
tional exposures and dental amalgam fill-
ings.6
Tremor is a classical symptom among vic-
tims of inorganic mercury poisoning, as well
as among methyl mercury poisoning vic-
tims. “Tremor Mercurialis” has been known
since antiquity.2 The tremor of methyl mer-
cury poisoning is different from physiologi-
147

Journal of Orthomolecular Medicine Vol. 10, No. 3 & 4, 1995
148
cal tremor and other pathological tremors in
frequency and amplitude.7
According to Störtebecker a possible ex-
posure to mercury should be considered in
the etiology of “Shaking Palsy” (Parkinson's
disease).2 He asks: “... why shouldn't a daily
release of small amounts of mercury from
dental amalgam fillings be capable of pro-
ducing similar neurological symptoms.”
Dental amalgams are the predominant
source of inorganic mercury and mercury
vapour in the general population.8 There is
found a direct correlation between the
number and surfaces of dental amalgam fill-
ings and the amount of mercury in the brain.9
Mercury vapour has no toxic threshold.10 No
exposure to mercury can therefore be con-
sidered totally harmless.
In light of these facts, the possible role of
dental mercury in etiology of Parkinson's
disease should be further studied.
References
1. Hamre HJ: Amalgam og sykdom. Oslo:
Vidarforlaget, 1993.
2. Störtebecker P: Neurology for barefoot
doctors in all countries. Correct Diagnosis by
simple methods. Täby/Stockholm: Störte-
becker Foundation for Research, 1988.
3. Semchuk KM, Love EJ, Lee RG: Parkinson's
disease: a test of the multifactorial etiologic
hypothesis. Neurology 43: 1173-80, 1993.
4. Komulainen H, Tuomisto J: Effects of heavy
metals on dopamine, noradrenaline and
serotonin uptake and release in rat brain
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199-204, 1981.
5. Rybicki BA, Johnson CC, Uman J, Gorell
JM: Parkinson's disease mortality and the
industrial use of heavy metals in Michigan.
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PR editors: Biological monitoring of toxic
metals. New York: Plenum Press, 1988.
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consentrations in the human brain and kidneys
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10.World Health Organization. Environmental
Health Criteria 118: Inorganic Mercury.
Geneva: World Health Organization, 1992.