It is suggested here that in most cases of Parkinson's disease the cause may be an environmental factor, possibly toxic, superimposed on a background of slow, sustained neuronal loss due to advancing age.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMedDate not supplied

Positron emission tomography after MPTP: observations relating to the cause of Parkinson's disease.

The dopa analogue 6-fluorodopa (6-FD) used with positron emission tomography (PET) allows in vivo visualization of dopamine and its metabolites in nigrostriatal nerve endings. We have now found abnormal 6-FD scans in four subjects exposed to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). None had parkinsonism. The results suggest subclinical damage to the nigrostriatal pathway. This is the first direct evidence that dopaminergic impairment can exist without clinical deficits. Here we discuss this finding in the context of the hypothesis that Parkinson's disease may stem from clinically silent damage to the substantia nigra, followed by slow attrition of neurones in this region because of its particular vulnerability to cell loss as a normal consequence of ageing.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMedDate not supplied

Manganese neurotoxicity: a review of clinical features, imaging and pathology.

Manganese intoxication can result in a syndrome of parkinsonism and dystonia. If these extrapyramidal findings are present, they are likely to be irreversible and even progress after termination of the exposure to manganese. Clinical features are usually sufficient to distinguish these patients from those with Parkinson's disease. The neurological syndrome does not respond to levodopa. Imaging of the brain may reveal MRI signal changes in the globus pallidus, striatum, and midbrain. Positron emission tomography reveals normal presynaptic and postsynaptic nigrostriatal dopaminergic function. The primary site of neurological damage has been shown by pathological studies to be the globus pallidus. The mechanism of toxicity is not clear.

Animals↗

PubMedDate not supplied

Occupational risk factors in Parkinson's disease.

BACKGROUND: An apparent excess of teachers and healthcare workers among the Parkinson's disease patients of a large tertiary care movement disorders clinic suggested the hypothesis that high exposure to viral (or other) respiratory infections in these occupations might be a risk factor for Parkinson's disease. METHODS: A case-control study of the association between occupation and Parkinson's disease was conducted. Cases (414) were all Parkinson's disease patients seen at the University of British Columbia Hospital Movement Disorders Clinic between 1986 and 1993, residing in Greater Vancouver, and under 65 in 1991. Controls (6,659) were randomly selected from the 1991 Canadian Census. FINDINGS: Parkinson's disease was associated with teaching (OR 2.50, 95% CI 1.67-3.74) and occupation in healthcare services (OR 2.07, 95% CI 1.34-3.20), but there were several other substantial associations, both positive and negative. INTERPRETATION: While referral bias cannot be ruled out, the authors find the consistency of the overall pattern of associations with the respiratory infection hypothesis striking.

Adolescent↗

PubMedDate not supplied

Parkinson's disease over the last 20 years: a personal view.

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History, 20th Century↗