Unraveling Autonomic Dysfunction in GBA‐Related Parkinson's Disease

BACKGROUND: Patients with Parkinson's disease (PD) and GBA gene mutations (GBA‐PD) develop nonmotor complications more frequently than noncarriers. However, an objective characterization of both cardiovascular and sudomotor autonomic dysfunction using extensive clinical and instrumental measures has never been provided so far. Survival is reduced in GBA‐PD regardless of age and dementia, suggesting that other hitherto unrecognized factors are involved. OBJECTIVES: To provide instrumental measures of pattern and severity of autonomic dysfunction in GBA‐PD and explore their correlation with other non‐motor symptoms and implications for clinical practice. METHODS: In this cross‐sectional study, 21 GBA‐PD and 24 matched PD noncarriers underwent extensive assessment of motor and non‐motor features, including neuropsychological testing. Cardiovascular autonomic function was explored through a comprehensive battery of indexes, including power spectral analysis of the R‐R intervals and blood pressure short‐term variability during resting state and active maneuvers. Dynamic Sweat Test was used to assess post‐ganglionic sudomotor dysfunction. RESULTS: Despite minimal or absent clinical correlates, cardiovagal and sympathetic indexes, heart rate variability parameters and sudomotor postganglionic function were more severely impaired in GBA‐PD than noncarriers (overcoming relatively preserved compensatory peripheral sympathetic function), suggesting more prominent cardiac sympatho‐vagal demodulation, efferent baroreflex failure and peripheral sympathetic dysfunction in GBA‐PD. Cardiovascular dysautonomia showed marginal correlations with cognitive impairment. CONCLUSIONS: Compared to PD noncarriers, GBA‐PD display more severe instrumental autonomic abnormalities, which may be underestimated by purely clinical measures, despite their relevance on morbidity and mortality. This supports the necessity of implementing instrumental autonomic assessment in all GBA‐PD, regardless of clinically overt symptoms.