Clinical phenotype of subjects with Parkinson's disease and orthostatic hypotension: autonomic symptom and demographic comparison.

The objective of this study was to characterize the phenotypic associations of orthostatic hypotension (OH) in Parkinson's disease (PD). One hundred fifty-nine subjects with PD underwent assessment including autonomic symptom severity scoring, disease-specific rating scales, and measurement of postural blood pressure response. Symptoms of autonomic impairment weakly correlated with disease duration and severity. A posture and gait instability (PIGD) motor phenotype was associated with greater severity of autonomic symptoms. Eighty subjects (50.3%) had OH. These subjects were older, more likely to be male, and taking larger doses of dopaminergic medications than those without OH. There was no difference in disease severity or duration between those with and those without OH. Symptomatic dizziness did not distinguish between groups, although subjects with OH had more symptoms of generalized autonomic impairment than those without. Progressive autonomic involvement may be linked to disease progression in PD, particularly in patients with a PIGD phenotype, but dichotomization into groups with and without OH is a relatively insensitive method for demonstrating this. Longitudinal studies of changes in autonomic reflex abnormalities, autonomic symptom profiles, and motor severity might clarify these associations.