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Neurology. 2011 Oct 11;77(15):1420-6. doi: 10.1212/WNL.0b013e318232ab4c. Epub 2011 Sep 14.

Does levodopa accelerate the pathologic process in Parkinson disease brain?

Author information

1
Queen Square Brain Bank for Neurological Disorders, UCL Institute of Neurology, UK.

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.

PMID:
21917769
DOI:
10.1212/WNL.0b013e318232ab4c
[Indexed for MEDLINE]

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