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Does levodopa accelerate the pathologic process in Parkinson disease brain?

Abstract:

Background: Several in vitro studies have suggested levodopa (L-dopa) to be toxic to dopaminergic neurons and that it can modulate the aggregation process of α-synuclein. We investigated the relationship between cumulative lifetime dose of L-dopa and nigral neuronal count and Lewy body (LB) pathology in Parkinson disease (PD).

Methods: Density of pigmented neurons was measured unilaterally in a single section of substantia nigra (SN) with delineation of the dorsal and ventral tiers in 96 cases of PD with well-documented clinical records relating to antiparkinsonian drug treatment. Cortical and nigral LB densities were determined using a morphometric approach.

Results: Mean lifetime dose of L-dopa correlated significantly (p < 0.001) with duration of PD in the entire study population (n = 96) and it was not possible to disentangle their individual effect. This was not the case in a subgroup analysis of younger onset patients with a longer duration of PD (n = 40) who showed no significant correlation between L-dopa and total SN neuronal density (p = 0.07), after adjustment for duration of illness. There was, however, a lower neuronal density in the ventral (p = 0.02) but not in the dorsal (p = 0.27) tier detected with the cumulative dose of L-dopa. We found no difference in L-dopa dose between Braak PD stages (p = 0.58). Furthermore, the subgroup analysis showed no relationship of L-dopa dose to either cortical (p = 0.47) or nigral (p = 0.48) LB density.

Conclusion: Chronic use of L-dopa in PD does not enhance progression of PD pathology as far as can be determined by our observations with SN neuronal counts and LB densities.

Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1212/WNL.0b013e318232ab4c

Authors


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Institution:
University of Oxford
Division:
MSD
Department:
Clinical Neurosciences
Role:
Author


More from this funder
Funding agency for:
Parkkinen, L


Publisher:
American Academy of Neurology
Journal:
Neurology More from this journal
Volume:
77
Issue:
15
Pages:
1420-1426
Publication date:
2011-09-01
DOI:
EISSN:
1526-632X
ISSN:
0028-3878


Pubs id:
pubs:579200
UUID:
uuid:39857240-2b7a-45ea-ad3c-b8455621abec
Local pid:
pubs:579200
Source identifiers:
579200
Deposit date:
2015-12-09

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