Objective: To examine the L-dopa-response (improvement in motor symptoms) in published cases of pathologically confirmed Parkinson’s disease (PD).

Background: L-dopa responsiveness supports the diagnosis of PD, and is embodied in the diagnostic criteria. However, there is variation between patients in the degree of L-dopa response. We assessed the L-dopa response in published cases of pathologically confirmed PD, and examined whether comorbid brain pathology was a factor in contributing to this variation.

Methods: A PubMed search (1977-2017) was conducted for reports of the L-Dopa response in pathologically confirmed PD (loss of pigmented neurons and Lewy body formation in the substantia nigra pars compacta), using the terms ‘L-dopa’ or ‘levodopa’, ‘Parkinson’s disease’, and ‘autopsy’. Papers were included when the motor improvement following L-dopa treatment had been assessed clinically.

Results: Out of 191 papers initially identified, 10 papers met inclusion criteria, encompassing 385 cases of pathologically confirmed PD. 57% were male and mean age at diagnosis was 63.8 years (SD 10.4). The L-Dopa motor response was reported in 354/385 patients (91.9%); this was graded as excellent in 142/354 (40.1%), good in 134/354 (37.9%), moderate in 50/354 (14.1%) and poor/absent in 28/354 (7.9%). 7 out of the 10 (70.0%) papers provided data on comorbid brain pathology, involving 150 of the 385 cases (39.1%). Alzheimer’s pathology was present in 44/150 (29.3%), cerebrovascular pathology in 80/150 (53.3%), diffuse Lewy body disease in 9/150 (6.0%), and amyloid angiopathy in 17/150 (11.3%). Comorbid pathology was associated with a poor/absent L-Dopa response in 7/12 (58.3%) cases in 1 study, but no further information was available.

Conclusions: More than half of autopsy-confirmed PD had only a good or moderate L-dopa response. Published data from prior studies are insufficent to conclude whether comorbid brain pathology influences the L-dopa response.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/variation-in-the-l-dopa-motor-response-in-pathologically-confirmed-parkinsons-disease/