Autonomic disorders predicting Parkinson's disease

Abstract

It is now well recognized that there is a premotor phase of Parkinson's disease (PD) with hyposmia and REM sleep behavior disorder caused by degeneration of specific CNS neurons. Most patients with PD describe autonomic symptoms at the time of diagnosis suggesting that these features may have potential sensitivity as clinical biomarkers of the premotor phase. The recognition that damage to peripheral autonomic neurons is present in the early stages of PD has led to a search for specific abnormalities in autonomic function that could serve as predictive biomarkers. There is evidence that constipation, urinary and sexual dysfunction and more recently decreased cardiac chronotropic response during exercise, are part of the premotor parkinsonian phenotype. The sensitivity and specificity of these features has yet to be accurately assessed. We briefly review the evidence for autonomic dysfunction as biomarker of premotor PD.

Keywords: Autonomic nervous system; Chronotropic insufficiency; Early detection; Lewy body disease; Orthostatic hypotension; Predictive biomarker; Premotor phase.

Figure 1. Distribution of incidental Lewy bodies in elderly subjects without clinical evidence of parkinsonism or dementia

Data are those reported by Bloch and colleagues [6]. Interestingly, the localization of Lewy bodies in this group was strikingly similar to those reported in PAF patients [28]. Information regarding non-motor symptoms (orthostatic hypotension, erectile dysfunction or urinary problems) was not collected by Bloch et al.