Dopa responsiveness in Parkinson’s disease

Sacha E. Gandhi*, Anahita Nodehi, Michael A Lawton, Katherine A. Grosset, Vicky Marshall, Yoav Ben-Shlomo, Donald G. Grosset

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

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Abstract

Background:
Dopaminergic responsiveness is a defining feature of Parkinson’s disease (PD). However, there is limited information on how this evolves over time.

Objectives:
To examine serial dopaminergic responses, if there are distinct patterns, and which factors predict these.

Methods:
We analyzed data from the Parkinson’s Progression Markers Initiative on repeated dopaminergic challenge tests (≥ 24.5% defined as a definite response). Growth-mixture modeling evaluated for different response patterns and multinomial logistic regression tested for predictors of these clusters.

Results:
1,525 dopaminergic challenge tests were performed in 336 patients. At enrolment, mean age was 61.2 years (SD 9.6), 66.4% were male and disease duration was 0.5 years (SD 0.5). 1 to 2 years after diagnosis, 48.0% of tests showed a definite response, but this proportion increased with longer duration (51.1-74.3%). We identified 3 response groups: ‘Striking’ (n = 29, 8.7%); ‘Excellent’ (n = 110; 32.7%) and ‘Modest’ (n = 197, 58.6%). Significant differences were as follows: striking responders commenced treatment earlier (P = 0.02), were less likely to be on dopamine agonist monotherapy (P = 0.01), and had better cognition (P < 0.01) and activities of daily living (P = 0.01). Excellent responders had higher challenge doses (P = 0.03) and were more likely to be on combination therapy (P < 0.01).

Conclusion:
Three distinct patterns of the dopaminergic response were observed. As the proportion of PD cases with definite dopa responsiveness increased over time, the initial treatment response may be an unreliable diagnostic aid.
Original languageEnglish
Pages (from-to)1113-1124
Number of pages12
JournalMovement Disorders Clinical Practice
Volume11
Issue number9
Early online date19 Jun 2024
DOIs
Publication statusPublished - 1 Sept 2024

Bibliographical note

Publisher Copyright:
© 2024 International Parkinson and Movement Disorder Society.

Keywords

  • Parkinson’s disease
  • dopa response
  • levodopa

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