Heart rate variability and sympathetic skin response for the assessment of autonomic dysfunction in leucine-rich repeat kinase 2 associated Parkinson's disease.

OBJECTIVES:We aimed to assess and compare autonomic function in Parkinson's disease (PD) associated with the leucine-rich repeat kinase (LRRK2) G2019S mutation (LRRK2-PD) and non-LRRK2 PD, by the study of heart rate variability (HRV) and sympathetic skin responses (SSR). METHODS:In a cross-sectional three-year study, fifty LRRK2-PD and fifty clinically matched non-LRRK2 PD patients were included. Cardiac parasympathetic functions were assessed using heart rate variation to deep breathing (HR-DB), to the Valsalva maneuver (HR-V) and to standing (HR-S) and the sympathetic autonomic system by sympathetic skin responses (SSR). RESULTS:Neurophysiological, parasympathetic and sympathetic dysautonomia were found in 78%, 69% and 37% of all PD patients respectively. Rates of dysautonomia in the LRRK2-PD and non-LRRK2 PD patient subgroups were 76% vs 80% (p = 0.405) for neurophysiological, 62% vs 76% (p = 0.123) for parasympathetic and 38% vs 36% (p = 0.500) for sympathetic dysautonomia. HR-S was the most frequently altered parameter in both groups, and was significantly associated with the tremor-dominant (TD) motor phenotype of PD in the total cohort (p = 0.004) and in LRRK2-PD (p = 0.015). In LRRK2-PD patients, female gender was associated with parasympathetic dysfunction (p = 0.024), and with altered HR-DB (p = 0.022). Early-onset parkinsonism was also significantly associated with preserved neurophysiological autonomic functions (p = 0.044) in LRRK2-PD. In non-LRRK2 PD patients, male gender was associated with early parasympathetic (p = 0.043) and sympathetic dysfunction (p = 0.007). CONCLUSION:Our study showed a roughly similar neurophysiological autonomic profile in non-LRRK2 PD and LRRK2-PD. The latter had some peculiarities with more marked parasympathetic dysfunction and more altered HR-DB in females, more altered HR-S in the TD-motor phenotype, and preserved autonomic functions in early-onset parkinsonism. These preliminary findings would require further investigations on larger genetically homogeneous cohorts to explore the multiple facets of autonomic dysfunction in PD.