Cardiovascular variability in Parkinson's disease and extrapyramidal motor slowing

Parkinson's disease (PD) is a degenerative neurological condition, associated with cardiovascular dysfunction. Many studies have utilised heart rate variability (HRV) to assess the autonomic nervous system in PD, but blood pressure variability (BPV) has received less attention. The purpose of the present study was to compare HRV and BPV between participants with established PD, extrapyramidal motor slowing (EPMS) (not reaching clinical criteria for PD), older healthy controls (OHC), and young healthy controls (YHC), in order to ascertain whether either of these measures can be used as an early marker of non-motor symptoms in PD. HRV was assessed at rest and during 2 min of slow deep breathing in 97 participants, divided into four groups: YHC (20-30 years; n = 19); OHC (67-83 years; n = 28); EPMS (59-91 years; n = 25) and PD (61-84 years; n = 25). Spectral analysis of blood pressure was performed on stable non-invasive recordings of blood pressure obtained in 76 of the participants. Low frequency (LF) and high frequency (HF) components, and the LF/HF ratio, were measured. Significant differences were only seen between the YHC and the three older groups. For HRV this was seen at rest and during 2 min of slow deep breathing, whereas for BPV this was only seen during 2 min of slow deep breathing. These data indicate that there are only age-related changes in HRV and BPV, and that neither technique is sensitive enough to provide an index of pre-clinical PD.