Preserved cardiovascular autonomic function predicts the response to initial MAO-B inhibitor treatment in Parkinson's disease.

INTRODUCTION

Monoamine oxidase-B (MAO-B) inhibitors enhance endogenous dopaminergic activity and are well tolerated in initial therapy for Parkinson's disease (PD). However, clinical responsiveness differs and reliable predictors of treatment response are unavailable.

METHODS

The association between baseline characteristics and motor responsiveness was examined in drug-naïve patients with PD initiated on MAO-B inhibitor monotherapy in comparison to levodopa treatment. Baseline assessments included motor severity, cardiovascular autonomic function (evaluated using the head-up tilt test), 123I-metaiodobenzylguanidine (123I-MIBG) myocardial scintigraphy and neuropsychological measures, including assessments of executive function, mood, and motivational states associated with endogenous dopamine levels. The motor outcome was defined as the percentage change in the Movement Disorders Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III score after 10 w.

RESULTS

Of 21 patients treated with MAO-B inhibitors, smaller orthostatic blood pressure declines at 3 min were strongly associated with greater motor improvement (ΔSBP: r = -0.520, p = 0.019; ΔDBP: r = -0.510, p = 0.022). Higher cardiac 123I-MIBG uptake predicted greater response (early: r = 0.518, p = 0.016; delayed: r = 0.516, p = 0.017), even after multivariate adjustment. In 18 patients treated with levodopa, treatment response was associated with cardiac 123I-MIBG uptake in univariate analyses but not orthostatic blood pressure changes; however, this association did not remain significant after multivariate adjustment.

CONCLUSION

Preserved cardiovascular autonomic function, particularly mild orthostatic hypotension, emerged as a predictor of a favorable response to MAO-B inhibitors in early PD, potentially aiding the individualization of initial dopaminergic therapy.